diff --git "a/JtFIT4oBgHgl3EQfZit-/content/tmp_files/load_file.txt" "b/JtFIT4oBgHgl3EQfZit-/content/tmp_files/load_file.txt" new file mode 100644--- /dev/null +++ "b/JtFIT4oBgHgl3EQfZit-/content/tmp_files/load_file.txt" @@ -0,0 +1,4233 @@ +filepath=/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf,len=4232 +page_content='arXiv:2301.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='11253v1 [hep-ph] 26 Jan 2023 Photo- and electro-production of narrow exotic states from light quarks to charm and up to bottom Xu Cao,∗ 1Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China 2University of Chinese Academy of Sciences, Beijing 100049, China 3Research Center for Hadron and CSR Physics, Lanzhou University and Institute of Modern Physics of CAS, Lanzhou 730000, China Abstract.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Accessing a full image of the inner content of hadrons represents a central endeavour of modern particle physics, with the main scientific motivation to investigate the strong interaction binding the visible matter.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' On the one hand, the structure of known exotic candidates is a fundamental open issue addressed widely by scientists.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' On the other hand, looking for new states of exotic nature is a central component for theoretical and experimental efforts from electron-positron machine and electron accelerator with fixed target to heavy ion and electron-ion colliders.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In this article we present a succinct short overview of the attempt to search for exotic narrow N∗ and Z states containing light quarks only or also charm, and its connotation for bottom regions (the latter two are also known as Pc (Zc) and Pb (Zb) states, respectively in the literature).' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' We address the effort of searching for exotic narrow N∗ and Z states in light quark sector.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' We focus on recent progress in searching for signal of Pc and Zc states photoproduction and its implication into the Pb and Zb photoproduction and their decay properties.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' We also discuss future perspectives for the field in electron-ion colliders, a good place to disentangle the nature of some of these states and investigate some other enlightening topics including QCD trace anomaly and quarkonium-nucleon scattering length.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 1 Introduction Since the birth of quark model [1, 2], the multi-quark states which do not fit into standard picture of baryon con- taining three quarks or meson containing a pair of quark- antiquark, became of interest both for experimentalists and theorists.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The study of these unconventional states would deepen our understanding of non-perturbative Quantum Chromodynamics QCD, with the ultimate goal to reach a comprehension of properties of strong interaction which bind the visible matter.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The mesons with exotic quantum numbers, which are not allowed by two quark structure, are good candidates of muti-quark states [3].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The COMPASS collaboration have performed a full partial wave analysis of multi-particle fi- nal states with the aim of searching for the π1 with quan- tum numbers 1−+ forbidden in quark model [4, 5].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The JPAC Collaboration claimed just recently solid evidence for the existence of π1(1600) as lightest hybrid meson af- ter tremendous efforts on pole analysis [6], while another π1 states with a lower mass of around 1400 MeV was not confirmed.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The width of π1(1600) was determined to be very wide, namely around 500 MeV.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Its isoscalar partner candidate, η1(1855) with a width of around 200 MeV, was just recently found by BESIII [7, 8].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The isovector partner of another broad exotic candidate f0(1700) was observed as a0(1700) by BaBar [9] and a0(1817) by BESIII [10, 11].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Compared to the broad states, the narrow states in the light ∗e-mail: caoxu@impcas.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='ac.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='cn quark sector are much easier to be established as exotica if they are really in existence.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The COMPASS collabora- tion also ascribed a narrow resonancelike structure around 1400 MeV coupling to f0(980)π with an isovector axial- vector nature, the a1(1420), caused by triangle singularity (TS) as the origin of a genuine three-body effect [12, 13], in line with previous theoretical calculations [14, 15].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Sev- eral models predicted charged Zs states (or Tφ in naming scheme of LHCb collaboration [16]) consisting of u ¯ds¯s, close to K ¯K∗ or K∗ ¯K∗ threshold [17].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' However, the BESIII Collaboration did not find their signals in the φπ spectrum of e+e− → φππ [18].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In the baryon sector, the famous Θ+ with the compo- nent uddu¯s disappeared in the large statistical nK+ and pK0 S spectrum [19].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Recently, both constituent quark mod- els [20, 21] and the models considering the QCD van der Waals force [22, 23] predicted the hidden-strangeness pen- taquark Ps (or PN φ ) states with qqqs¯s component (q: light quark).' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The QCD sum rule [24] and unitary coupled- channel approximation [25] did not exclude the existence of the φp bound state.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Attractive φp interaction was fa- vored by correlation function from Lattice QCD calcula- tion [26] and ALICE measurement [27].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The Λ+ c → φpπ0 was shown to be not a good choice for the search of Ps due to the presence of triangle singularities and the tiny phase space predicted by theoy [28].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' As a matter of fact, Belle Collaboration showed no evident signal of resonance in its φp spectrum [29].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Furthermore, no sharp peak of Ps was found in near-threshold total cross section of γp → φp, but a non-monotonic structure, found in the differential cross section by LEPS Collaboration [30], would imply a very wide (∼ 500 MeV) states N∗(2100) [31, 32].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' This state, together with N∗(1875), were proposed to be exotic baryons [33].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Alternative assignment was argued to be N∗(1875) and N∗(2080) (labeled as N∗(2120) in present version of PDG [34]), which are close to KΣ∗ and K∗Σ thresholds, respectively [35].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' However, these states decay fast to their ground state — nucleon, so their widths are all bigger than 100 MeV.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' As a result, it needs further ef- fort to unambiguously establish them as exotic states.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' On the other hand, the narrow states can be hardly incorpo- rated into the traditional spectrum.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' For instance, the N∗ and ∆∗ spectrum [36], consisting of states with excitation of internal degrees of freedom of nucleon and ∆, must be wider than 100 MeV because of their strong coupling to πN, ηN and ππN, etc.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' So the existence of narrow nucleon resonances would serve as excellent evidence of exotica.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A renowned narrow structure at around 1680 MeV close to KΣ threshold was found by Graal group in η photoproduction off neutron [37] and confirmed by many other experiments [38–42].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' It was explained by coupled- channel effects due to S 11(1650) and P11(1710) in a K- matrix approximation coupled-channel model [43, 44], which was further used to study Compton scattering off the proton [45].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Alternative interpretations were the interfer- ence in the 1/2− wave - S 11(1535) and S 11(1650) - in chi- ral quark model [46] and Bonn-Gatchina analysis [47, 48], and loop contributions from associated strangeness thresh- old openings [49].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The situation would be clarified if the neutron helicity amplitudes of N∗ were better con- strained.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Much progress has been made recently in this direction because of the newly released data of γn re- actions [50–52], also γn → K0Λ/K0Σ0 from A2 [53], BGOOD [54], and CLAS Collaboration [55], γn → K+Σ− from CLAS Collaboration [56, 57], and γn → π0n from A2 Collaboration [58], γn → π−p from CLAS [59] and PIONS@MAX-lab [60, 61] and CLAS Collaboration [62].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' So the model analysis of this structure was expected to be refined soon.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The signal of its isospin partners was claimed to be present in the γN → ηπN by Graal [63], however, it was not confirmed by CBELSA/TAPS [64] and A2@MAMI groups [65, 66].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Together with this state, a narrow structure at 1720 MeV close to ωp threshold was also observed in γp → γp [67], quasifree γn → ηn [38] and high-precision πp elastic data from EPECUR Collab- oration [68, 69].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Whether these states correlate with each other is under investigation.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A coupled-channel calcula- tion showed that the narrow structures in Compton scat- tering γp → γp are feeble after considering carefully all the contribution of known N∗ and ∆∗ [45].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In this paper as an exemplar of the major obstacles we further demon- strate a full set of beam polarization of proton Compton scattering up to the third resonance region in Sec.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 3.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' An- other narrow resonance near the η′p threshold is possibly existing in the GRALL data on the beam asymmetry as discussed by the Bonn-Gatchina approach [70].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Consider- ing the connection of η′ and η mesons to gluon dynamics [71], the structures near η(′)p threshold are of renewed in- terest.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The tension seems to be relieved when one moves to heavy quark sector.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Since the uplift discovery of the χc1(3872) by the Belle collaboration [72], a rich spectrum of exotic mesons has brought into an intriguing prospect of hadron physics.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Among them, the charged Zc (or Tψ) states with narrow width play a special role because of their probable u ¯dc¯c composition.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The Z+ c (4430) with a mass of 4478 +15 −18 MeV and a width of 181 ± 31 MeV was found in the π±ψ(2S ) spectrum of B0 → K∓π±ψ(2S ) by Belle [73, 74] and confirmed in ¯B0 → K−π+ψ(2S ) [75] and ¯B0 → K−π+J/ψ [76].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The LHCb group determined its spin-parity unambiguously to be 1+ [77].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Up to now its other decay modes have been not found.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The Zc(3900) with a mass of 3887.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='2 ± 2.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='3 MeV and a width of 28.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='2 ± 2.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='6 MeV was discovered in the J/ψπ± spectrum by BE- SIII [78] and Belle [79] and confirmed by CLEO-c [80].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The BESIII collaboration identified it as an isovector state with spin parity 1+ [81, 82], and found its decay chan- nel D ¯D∗ [83, 84].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' At present, Zc(3900) is the lowest Zc state while Z+ c (4430) is the highest one, limited, however, only by the kinematical coverage of the accelerator.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The properties of other Zc states are less known, e.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='g.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' the spin- parity of most of them are not well determined [85].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' More- over, LHCb discovered a much narrower doubly charmed tetraquark candidate T + cc(3875) of isoscalar characteristic near D∗+D0 threshold, intriguingly stable with respect to the strong interaction [86, 87].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The narrow exotic baryons in the charm sector, known as pentaquark states Pc (or PN ψ), are predicted within the framework of the coupled channel unitary approach with the local hidden gauge formalism [88].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' This is confirmed by many models with other prescriptions [89–91].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The LHCb collaboration reports evidently three narrow states Pc(4312), Pc(4440) and Pc(4457) in the J/ψp invariant mass spectrum of Λ0 b → J/ψpK− decay with the width of 9.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='8±2.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='7+3.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='7 −4.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='5 MeV, 20.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='6±4.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='9+8.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='7 −10.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='1 MeV, and 6.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='4±2.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='0+5.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='7 −1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='9 MeV, respectively [92, 93].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' They also announced the ob- servation of another Pc(4337) state with a width of 29 +26 −12 +14 −14 MeV with a lower significance in B0 s → J/ψp ¯p de- cays [94].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Their component is likely to be qqqc¯c and their nature is yet under extensive investigation.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Hypernuclei are nuclei within which one or more nu- cleons are substituted by hyperons, namely Λ, Σ or Ξ, which carries a new quantum number, not contained nor- mally inside the nuclei, the strangeness.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The concept of ’hyper’ can be extended to exotic mesons, predicted by several framework [95–98] as strange exotic mesons, where one quark is replaced by a strange quark.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Just re- cently three T θ ψs1 states, namely the Zcs(3985) unveiled in D− s D∗0,+ + D∗− s D0,+ distribution by BESIII colaboration [99, 100] and Zcs(4000,4020) found in B+ → J/ψφK+ by LHCb group [101], reveal a new dimension to the traditional family of exotic mesons, beyond the hidden- charm and hidden-bottom components.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In the molecular scenario, the Zcs(3985) is the ideal candidate of strange partners of the Zc(3900) and Zc(4020) under SU(3)-flavor symmetry [102].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' From the global fit to the available data, it is found that present precision is insufficient to disentan- gle those exotic mesons to be bound or virtual or resonant states.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The existence of Zcs(4130), the heavy quark spin symmetry partner of Zcs, plays a key role in distinguish- ing various models and deciphering whether Zcs(3985) and Zcs(4000) are the same state.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' So it is essential to hunt for it at running and future facilities.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Its clue is weakly traced in the data of ¯B0 s → J/ψK−K+ at LHCb [103] and e+e− → K+D∗− s D∗0 + c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' at BESIII [104].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Surprisingly, it would be produced under lower center-of-mass (c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='m.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=') en- ergy of e+e− than that of Zcs due to the inverted coupling hierarchy of triangular singularity at electron-positron an- nihilation [103].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' This prediction would be confirmed by increasing the amount of collected events at BESIII.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Ex- citingly, the X0,1(2900) (or Tcs0,1) in the D−K+ channel were clearly observed by LHCb group as the first charm- strange exotic hadrons with open flavor and without a heavy quark-antiquark pair [105, 106].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The strange pen- taquark states Pcs (or PΛ ψs) in J/ψΛ spectrum, predicted as ¯D(∗)Ξc molecule and strange partner of Pc [88], were also found at LHCb [107, 108].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Molecules configurations are the most popular scenar- ios for understanding the nature of these states because of the closeness of corresponding open charm channel, though other explanations are not excluded at all, e.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='g.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' tetraquark or hadrocharmonium states, see Refs.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' [109– 117] for review.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A complete spectrum for hadronic molecules seems to be emergent and could be nicely or- ganized by heavy quark spin and flavor symmetries [118].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' For instance, a isovector axial-vector multiplet in the charm and bottom sectors is predicted by further combin- ing SU(3) flavor symmetry for the potential between heavy mesons [102, 119–124].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In the bottom sector, two charged states T b Υ1, namely Zb(10610) and Zb(10650) with the component of u ¯db¯b, have been found a decade ago in Υ(nS )π (n=1,2,3) and hb(mP)π (m=1,2) spectrum by Belle Collaboration [125].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A most recent effort in search of the bottomonium equiva- lent of the χc1(3872) state decaying into ωΥ(1S) by Belle II [126] observed no significant signal for masses between 10.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='45 and 10.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='65 GeV.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Several isoscalar states of spin J = 0, 1, 2 with positive parity were also foreseen by different models soon after the discovery of Zb [118, 127, 128].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' But the strange partners Zbs (or TΥs) and isoscalar analogues have not been found yet.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The double-beauty states as the bottom partner of T + cc(3875) was predicted by heavy-quark symmetry based on the observation of Ξ++ cc [129, 130].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Under SU(3) flavor symmetry for the potential between heavy mesons and baryons, the correspondence of Pc in the beauty sector, labeled as Pb (or PN Υ) here, are supposed to be surely in existence [129, 131–133].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The analogues in light quark sector, the aforementioned Zs and Ps, are absent experimentally in this jigsaw puzzle, with the only exception of Λ(1405) [134, 135] and Ds0(2317) [136–141] as a two pole structure of the scattering matrix close to the nominal resonant position.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' These facts are challeng- ing our understanding of the strong interaction at low en- ergy, which anticipates a moderate violation of SU(3) fla- vor symmetry.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Much effort has been taken to the study of pion- and photo-induced reactions for the purpose of search- ing for these narrow exotic candidates.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' However, the motivation to study these processes is far beyond this.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The photoproduction of these states in two body final states, e.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='g.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' near-threshold J/ψ and Υ exclusive photo- production off the proton, is an exceptional place to ex- clude their non-resonant possibility.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Triangle singularity (TS) is often happened in reactions with three body final states.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' For instance, various triangle diagrams for π−p → J/ψpπ− [142], Λ0 b → J/ψpK−, and B0 s → J/ψp ¯p [143– 145] have been already extensively explored.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Though TS can be present in reactions with two body final states, for example the γp → Vp reaction (with V being a vector meson hereafter), it is very hard to satisfy the on-shell conditions required by the TS, as discussed in detail in the literature [146] and a recent review [116].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' So from the very beginning photoproduction and electroproduction reactions are suggested to disentangle the true resonance nature of exotic states for the advantage of being free of the disturbance of kinematical effects [147].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' If events are statistically abundant, we may move one step further to nail down the quantum numbers of some of those exotic states with the help of angular distributions and polarized observables.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Moreover, the photo- and electro-production can make maximum use of total energy to search for narrow exotic state of higher mass.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='Nearly all exotic states are observed by the electron-positron annihilation and weak decays of B, Λb and their strange partner.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Thus the maximal mass of a charmonium-like or penquark state produced in this way is limited to be around 5.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='0 GeV by the mass difference be- tween the the ground state bottom-hadrons and K mesons.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The utmost mass of states touched by electron-positron colliders is below 5.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='0 GeV as well, bounded by the de- signed c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='m.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' energies.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The photo- and electro-production are likely to extend considerably the mass range up to high excitation region, another way to probe the internal structure of exotic states.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The clean photo- and electro- production are also complement to prompt production pro- cesses at hadron colliders with huge backgrounds and other novel metheods [148–150].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The COMPASS detector, abbreviation of COmmon Muon Proton Apparatus for Structure and Spectroscopy, is a fixed-target experiment with muon, pion and proton beams and polarised proton and deuteron targets at the Su- per Proton Synchrotron (SPS) at CERN.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' By using the pho- toproduction with a muon beam, it covers the range from 7 GeV to 19 GeV in the c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='m.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' energy of the photon-nucleon system.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' It has studied not only the aforesaid light exotic mesons, but also the upper limit of γp → χc1(3872)p [151] and γp → Z+ c (3900)n [152].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The GlueX experiment located in Hall D at Jefferson Lab (JLab) measured the γp → J/ψp reaction for the first time and set model- dependent upper limits on the branching fractions of Pc decay [153].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The Hall C at JLab proposed to search for the Pc with higher precision by the same reaction [154, 155] and published just recently the data on differential cross sections [157].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The proposed electron-ion collider in the US (US-EIC) [158–160] and China (EicC) [161–163] are potential platforms to resolve the nature of those states.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='m.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' energy of the latter machine is close to that of COMPASS but with more than one order higher luminos- ity.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In this topical review we will first outline the model framework of the electro- and photo-induced reactions in Sec.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 2.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Afterwards we retrace a hunting for narrow exotic candidates in the light quark sector in Sec.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 3, followed by a detailed inspection of the charm sector in Sec.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 4 and the bottom sector in Sec.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 5, respectively.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In particular in last two sections we briefly summarize to-the-date efforts and give an outlook to the future precision frontiers of photo- and electro-production of heavy quarkonium-like states of narrow widths, and stress their impact on the understand- ing of mystery in light quark sector.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Several critically rel- evant topics are discussed as well with an emphasis of the model dependence.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' We give a short summary and perspec- tive in Sec.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 6.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 2 Outline of the Framework Since mesons and baryons are observed as asymptotic QCD effective degrees of freedom by experiment, the effective models respecting basic symmetries are con- structed on the hadron level to describe exclusive photo- production of meson in s-, u- and t-channel.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The am- plitudes of tree diagrams in Fig.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 1 are easily calculated by means of effective Lagrangian [164, 165], covariant L- S scheme [166–168], or in the helicity formalism [169], whose details have been presented extensively in the lit- erature.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The experimental observables, i.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='e.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=', the cross sec- tions and polarization observables, could be easily calcu- lated by partial-wave techniques [170].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In the light quark sector the model parameters are under good control by a si- multaneous fit to the amount of data of available channels.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The parameters of resonances from low to high excitation are extracted with continuous improvement of accuracy.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Herein we briefly outline the essentials of the framework, in particular the main feature of technique and reaction kinematics, but leave the theories and models of hadron structure into other comprehensive reviews [109–117].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' .' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' If a resonant baryon or baryon-like state R is long- lived, the production cross section in s-channel γp → R → γ V γ γ p p′ p p′ p p′ V V Figure 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The s-, u- and t-channel kernel of γp → V p with V being γ, J/ψ, Υ or other light mesons or heavy axial-vector mesons.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The red lines label ρ, φ, ω, J/ψ, Υ if VMD model is implemented.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The exotic baryon candidates N∗, Pc and Pb are potentially produced in s-channel γp → γp, γp → J/ψp and γp → Υp, respectively, whereas the exotic axial-vector meson candidates V are likely appearing in t-channel.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Vp can be simplified to be a Breit-Wigner line shape, σR = 2 J + 1 (2 s1 + 1)(2 s2 + 1) 4 π k2 in Γ2 4 ×B(R → γp) B(R → Vp) (W − M)2 + Γ2/4 (1) Here kin is the magnitude of three momentum of initial proton in the c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='m.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' frame, W is the c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='m.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' energy of γp sys- tem, and s1,2 are the spins of initial photon and proton, re- spectively.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' This works quite well for the Pc and Pb because of their very large masses in comparison of their widths.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' So a product of branching ratios B(R → γp) B(R → Vp) can be model independently extracted from the cross sec- tion measurements.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The radiative decay width B(R → γp) is proportional to the B(R → Vp) via the vector meson dominant (VMD) assumption that vector mesons dominate the interactions of hadrons with electromagnetism [133,' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 171]: B(R → γp) = 3 Γ(V → e+e−) αMV � L fL � kin kout �2L+1 B(R → Vp) (2) Here α is the fine structure constant,' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' L is the orbital ex- citation between the V and the proton,' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' fL is the fraction of decay in the relative partial wave,' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' and kout is the mag- nitude of three momentum of final nucleon in the c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='m.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' frame.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Before proceeding further a few remarks shall be made on VMD, which is introduced as an important phe- nomenological concept before the era of quantum chro- modynamics [172].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The model has been validated for the lightest vector mesons ρ, ω and φ as the constitution of the hadronic components of the physical photon [173, 174], though it is eliminated as a possible description of deep in- elastic scattering [175].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In the light quark regime, VMD is not a prerequisite for the framework since electromagnetic helicity amplitudes could be fixed with controlled uncer- tainties by plenty of photoproduction data.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Generalization of the VMD model to heavy vector quarkonium has been proposed to drastically fail [176].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' To identify the cases where VMD fails is of its own importance.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A future effort would improve the estimating the momentum dependent photon-to-quarkonium transition strength.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The exotic meson candidates V can be produced through t-channel of γp → Vp and then reconstructed and analyzed by their subsequent decay.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' At high energies they are searched for by diffractive process as mentioned for the a1- and π1-meson.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The mechanism for the pro- duction of axial-vector Charmonium states is further de- tailed below in Sec.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 4.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' As the non-resonant background to the s-channel contributions, the t-dependence contribu- tions (or angular distributions) can be model-dependently calculated.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The total cross section due to the t-channel processes is appropriately estimated by σV = NWδ(Q2) = NWα+β ln(Q2+M2 V) (3) which is suggested by the empirical formula of deeply vir- tual meson production (DVMP) γ∗p → Vp [177].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Here the units of MV and W are in GeV and that of the photon V V T GMB T = + Figure 2.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A diagrammatic representation of K-matrix approxi- mation coupled-channel model.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Dashed lines are mesons or pho- ton, and solid lines are baryons.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' virtuality Q2 in GeV2.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The merit of this simple param- eterization is that it is applicable to various mesons with proper Q2 dependence.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The parameters α and β have been determined by the DVMP data to be α = 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='31 ± 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='02 and β = 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='13 ± 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='01 [177].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The corresponding δ(Q2 = 0) = 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='89 is confronted with the perturbative QCD prediction δ ∼ 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='7 [178], whose difference is not satisfactorily ex- plained.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The normalization N of γp → Υp is determined by the data at high energies to be 2.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='62 ± 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='38 fb, where the experimental error of W is not included [179].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Its ex- trapolation to low energies is suggested to be an upper limit of the production rates [179].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A more appropriate evaluation for the near-threshold region is to include the two-body phase space factors for Eq.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' (3), or use the for- mula based upon Pomeron exchange [180] with the inter- cept of Regge trajectory close to 1 [181, 182], or alterna- tively two-gluon and three-gluon exchange [183].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' These schemes are widely applied for J/ψ of which the normal- ization N is well fixed by the data from near-threshold up to W = 100 GeV [154].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' At the low-energies several hidden and open strange channels, e.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='g.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' γN, πN, 2πN, ηN, ωN, πN, KΛ, and KΣ, are involved and the available data are sufficient for a more comprehensive analysis.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A coupled-channel unitary La- grangian model could be constructed with an input of tree level diagrams V fa in Fig, 1, T fi = V fi + V faGabTbi (4) as graphically illustrated in Fig.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 2.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The i, f and a(b) are the initial, final, and intermediate states, respectively.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Besides partial wave analyses on the basis of proper parameteriza- tion of amplitudes [47, 48, 184, 185], several dynamical frameworks are proposed for the interaction kernel V fa in order to resolve approximately the coupled-channel equa- tion [186–191].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Alternatively, another Kfa kernel could be defined as, Kfi = V fi + V faReGabKbi (5) As a practical approach, the K-matrix approximation as- sumes that the real part of the propagator Gab is vanishing and the coupled-channel equation is accordingly reduced to [164, 165]: T fi = Kfi + iKfaImGabTbi (6) in terms of Kfa = V fa accommodating the reaction mech- anism of the pion- and photo-induced reactions in the res- onance region [43, 44, 192, 193].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The summation over in- termediate states a(b) is running only over hadronic states but neglecting the γN so gauge invariance of the Comp- ton amplitude is easily retained [45, 164].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Thus, unitarity holds with the merit of technical simplicity and flexibil- ity but at the cost of analyticity.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' As a result, all states are treated as Breit-Wigner resonances as the same in Eq.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' (1) and neither of them is dynamically generated.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The frame- work is readily applicable to high energies if several chan- nels, e.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='g.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' various hidden and open charm or bottom fi- nal states are involved into the analysis.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Especially, the kernel is envisaged to incorporate the dynamical model of internal structure.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' However, by the lack of data, the anal- ysis at present is restricted to the single channel case with the aim to estimate the photoproduction rates of various quarkonium and exotic quarkoniumlike states in the kine- matical regime of running fixed-target machine and future electron-ion colliders.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A few states of particular interest are used as benchmarks with the help of the limited exper- imental information.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The reaction dynamics, sensitive to specific process, are separately discussed in later sections.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' With the input of t-dependent photoproduction cross sections, the differential cross section of exclusive meson electroproduction can be directly calculated under the one photon approximation [154, 155]: dσep→eVp dQ2dydt = ΓT(1 + ǫ RL)f(Q2)dσγp→Vp dt (7) where y is the fractional energy of the incoming electron transferred to the virtual photon in the target rest frame.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The parameterization of logitudinal-to-transverse ratio RL and form factor f(Q2) are widely studied in the litera- tures [194].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Generally the RL+1(m < 0) and f(Q2)(m > 0) are written as, \uf8eb\uf8ec\uf8ec\uf8ec\uf8ec\uf8ed n M2 V n M2 V + Q2 \uf8f6\uf8f7\uf8f7\uf8f7\uf8f7\uf8f8 m (8) where the parameters can be determined by a global fit to vector meson electroproduction data.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The study of available ep → eJ/ψp data gives valuable informa- tion on the Q2 dependence of heavy quarkonium produc- tion [194, 195].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' This is widely used by the simulation of JLab-12 [196] and US-EIC [154, 155].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The virtual photon flux is defined as, ΓT = αem 2 π y2 1 − ǫ 1 − x xQ2 (9) where the polarization is ǫ = (1 − y − 1 4 γ2y2)/(1 − y + 1 2y2 + 1 4γ2y2) with γ = 2xMN/Q.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' For high energies ǫ is approaching unity, for instance the averaging polarization < ǫ >≃ 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='99 at HERA.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Other variables are: x = Q2 W2 − M2 N + Q2 , y = Q2 x(s − M2 N) (10) The kinematical coverage is limited to: 1 ≥ y ≥ Q2 + (MV + MN)2 − M2 N s − M2 N � s − Q2 ≥ W ≥ MV + MN t0(y, Q2) ≥ t ≥ t1(y, Q2) m2 ey2 1 − y ≤ Q2 ≤ ys + (1 − y)M2 − (MV + MN)2 with the definition of t0,1 = (Q2 + M2 N)(M2 V − M2 N) ± λ(Q2)λ(M2 V) 2W2 −1 2(W2 + Q2 − M2 V − 2M2 N) (11) where ± corresponds to 0 and 1, respectively.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The Käl- lén triangle function are λ2(x, y, z) = x2 + y2 + z2 − 2xy − 2yz − 2zx, λ(Q2) = λ(W2, −Q2, M2 N), and λ(M2 V) = λ(W2, M2 V, M2 N).' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' As a substitute the t-integrated photopro- duction cross section can be used [197]: σep→eVp = � dW W � dk � dQ2 Γ(k, Q2) f(Q2)σγp→Vp(W) (12) where Γ(k, Q2) is flux under equivalent photon approxima- tion with k being the photon energy.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 3 Exotic candidates in light quark sector In the light quark sector as probed in the πN and γN re- actions the resonant line shape and non-resonant back- ground are much more involved than those parameteri- zations in Eqs.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' (1) and (3).' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Before attempting to search for narrow exotic baryon resonances amongst a consider- able amount of the data, one has to exclude other possi- bilities, e.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='g.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' interference, threshold openings or triangle diagrams, in a sophisticated but reliable manner.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Afore introduced coupled-channel model in K-matrix approxi- mation is well suited for this purpose.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' It excavates the known resonances by fitting both isospin I = 1/2 and I = 3/2 partial waves to the available data.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Other dy- namical approaches respecting analyticity are successfully constructed, namely the Jülich-Bonn-Washington model [198, 199] and the ANL-Osaka model[189, 191].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The for- mer has already extended to study the electroproduction of the π and η mesons [200, 201] and just recently KΣ photoproduction [187].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The latter is also used to extract Λ∗ and Σ∗ from K−p reactions [202, 203], whose result together with Bonn-Gatchina solution [204–206] are en- countering the rather complex structure of the Λ(1405) state.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Incidentally, conventional wide resonances are in- corporated in all models, though the spectrum would dif- fer case by case.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' As also noted, strong evidence is claimed for new wide resonances near 1900 MeV in γp → KΛ by the Bonn-Gatchina group [185, 207].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' This relieves the famous shortcoming of missing resonances in the conven- tional quark model, which predicted more baryonic states of three-quark than seen in the πN and γN scattering.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A similar issue reappears in lattice QCD [208] and Dyson- Schwinger calculations [209, 210] under the situation of Table 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The parameters of two exotic N∗ added in the coupled-channel model.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The Breit-Wigner (BW) masses and total widthes Γtot are given in MeV.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The sign of electromagnetic helicity amplitudes is not determined.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' N∗ BW mass Γtot Ap 1 2 ( 10−3 GeV−1/2) S 11(1680) 1681 2 ± 1 32 ± 10 P11(1720) 1726 2 ± 1 35 ± 10 unphysical π mass.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Contrarily, quark-diquark models give rise to too less states, for instance, failing to accommodate P13(1900) and F15(2000) states, though remedy would be put forward.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Besides the narrow structures in several channels of pseudo-scalar meson as outlined in Sec.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 1, those signals in Compton scattering off the proton in the resonance re- gion need to be carefully analyzed.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' As a consequence of smallness of the electromagnetic couplings constant, the electromagnetic reactions decouple essentially from the hadronic ones in a coupled-channel model.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' This is real- ized for the first time with the help of the techniques at hand after fixing properly the isospin I = 3/2 amplitude by the KΣ channel [211].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' It results into a refined extrac- tion of the amplitudes of Compton scattering off the proton [45].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' After a full combined analysis of pion-and photo- induced reactions, beam polarization of proton Compton scattering can be fairly described without free parameters as shown by the solid lines in Fig.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 3.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Selected angular bins have been already published [45].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The leading con- tribution stems from P33(1232) and D13(1520) in first and second resonance region.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' As shown by the shaded area, the agreement is systematically improved if adjusting a bit the helicity couplings of D33(1700) and F35(1905) reso- nances, which is predominant in the energy range between 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='6 GeV and 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='8 GeV.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Therefore the room left to host new states is lower than 1σ if judged by the statistical significance.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Still, two ex- otic N∗ states seen closely above the KΛ and ωN thresh- olds are added into the analysis as indicated by the dotted lines in Fig.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 3.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Their masses are fixed by comparison to corresponding structures observed in ηp channels and πp elastic differential cross sections.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Other parameters are extracted in Table 1, of which the errors are mainly driven by the data of the scattering angles 131◦, 143◦, and 157◦ from GRAAL collaboration [67].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Their electromagnetic helicity amplitudes in Tab.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 1 are found to be of moderate magnitude.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Apart from the resonance region, the nucleon Comp- ton scattering at low energies is a probe of the nucleon’s polarizabilities, a measure of their response to an external electromagnetic field of moderate magnitude [212].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Sim- ilarly a partial-wave analysis of the world data set below the pion-production threshold is accomplished [213].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The ∆(1232) contribution to the scalar and spin polarizabilites is noticeable, and the D13(1520) plays a role in the pro- ton’s magnetic polarizability [214].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The effect of any other resonances is invisible.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' As a result, full understanding of nucleon resonances is established in Compton scattering from low energies where chiral perturbation theory is ap- plicable, up to 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='8 GeV in which a coupled-channel ef- fective Lagrangian model shall be constructed.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Our K- matrix analysis of the resonance region gives insight into the highly non-trivial structures in Compton scattering, however, calling for higher precision data.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In this clas- sic case the obstacles and complexities have been demon- strated which are encountered in the hunting for narrow exotic states in the light quark sector.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In particular, it re- flects the insufficiency of our understanding of the baryons as relativistic three-quark bound states [215], in which 1 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='5 0 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='5 1 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='2 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='4 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='6 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='8 90 1 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='5 0 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='5 1 Σ 125 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='5 0 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='5 157 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='2 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='4 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='6 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='8 W (GeV) 75 120 143 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='2 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='4 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='6 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='8 65 115 135 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='2 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='4 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='6 1.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='8 105 131 Figure 3.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The beam polarization of proton Compton scattering versus c.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='m.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' energies W for different angular bins (in unit of degree as labeled in each figure).' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Solid lines are the result with the parameters in Ref.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' [211], and shaded area are the improved result with adjusting the helicity couplings of D33(1700) and F35(1905) resonances.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Dotted lines are the one for adding S 11(1680) and P11(1720).' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The data in the scattering angles 131◦, 143◦, and 157◦ are from GRAAL collaboration [67] and others are referred to the compilation in Ref.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' [164].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' other effects like diquark correlations [216], gluonic ad- mixtures and vacuum polarization are also important.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In a word, after a lot of effort none of the light narrow exotic states is firmly established.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' It is foreseen that once high statistics data will become available in future, partial wave analyses will be feasible for diffractive processes at COMPASS and CLAS [217] and annihilation reactions at BESIII [218] and at PANDA [219].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Other reactions and decays to study them are suggested from the theoretical perspective [33, 220–223].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A search in the electroproduc- tion of the nonstrange channels is viable when more mea- surements will become available [200, 201, 224].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Whether they are accessible at EicC and US-EIC needs careful in- vestigation by means of available tools.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 4 Exotic candidates in Charm sector: In the heavy quark sector the resonance line shape and non-resonant background are much simpler because of the narrow width of the established states.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Yet, coupled- channel analysis is desirable with the aim to understand the nature of states by exploring their pole structures.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The effort along this direction is made in several cases like Pc [225], χc1(3872) [226–228], Zc(3900) [229] and T + cc [230, 231].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' A complete analysis is postponed in most sit- uation by the shortage of data, which are usually available only for the dominant channel.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The single channel frame- work in Sec.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 2 is straightforwardly applied to the electro- production of these states with the input of photoproduc- tion cross sections if experimentally available.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Otherwise the radiative decay width B(R → Vp) is required to be theoretically estimated, however, definitely of big model dependence.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The pentaquark states are unveiled via their decay to J/ψ plus proton or hyperon.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Even before and also soon after the discovery of Pc it is speculated that Pc can be photoproduced in the s-channel reactions as in Fig.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' 1 with the photon converted first to J/ψ [147, 171, 232, 233].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The conventional reconstruction route would be hidden charm channels involving J/ψ or ηc [234].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' Considering that they would decay more favorably into open charm channel, the reaction γp → ¯D0Λ+ c is investigated within an effective Lagrangian approach [235] and the Regge-plus-resonance model [236].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' The non-resonant background can be pa- rameterized as the t-channel diagram with gluon, Pomeron or meson exchange, respectively, whose angular distribu- tions are different from those of the pentaquark states.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' It is naturally conjectured that the differential cross sections fixed by the helicity dependence can be used to disentangle the spin and parity of these resonances [147].' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content=' In light of 4 6 8 10 12 14 16 W / GeV 3 − 10 2 − 10 1 − 10 1 10 2 10 3 10 4 10 2 t / GeV 1 10 2 10 20 GeV × 3.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='5 GeV ψ epJ/ → ep 2 1 GeV ≤ 2 0.' metadata={'source': '/home/zjlab/wf/langchain-ChatGLM/knowledge_base/JtFIT4oBgHgl3EQfZit-/content/2301.11253v1.pdf'} +page_content='055