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.On ...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.On the one hand,the structure of known exotic candidates is a fundamental open issue addressed widely by scientists.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.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).We address the effort of searching for exotic narrow N∗and Z states in light quark sector.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.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.展开更多
The J/ψ hadronic decays provide good laboratory to search for the hybrid states with exotic quantum numbers. A full Partial Wave Analysis （PWA） is performed to the generated Monte Carlo J/ψ→ ρηπ data, based on...The J/ψ hadronic decays provide good laboratory to search for the hybrid states with exotic quantum numbers. A full Partial Wave Analysis （PWA） is performed to the generated Monte Carlo J/ψ→ ρηπ data, based on the design of BESⅢ detector, to study the sensitivity of searching for a possible exotic state at BESⅢ.展开更多
We study possible exotic J^（PC）=0~＋- states using tetraquark interpolating currents with the QCD sum rule approach. The extracted masses are around 4.85GeV for the charmonium-like states and 11.25 GeV for the botto...We study possible exotic J^（PC）=0~＋- states using tetraquark interpolating currents with the QCD sum rule approach. The extracted masses are around 4.85GeV for the charmonium-like states and 11.25 GeV for the bottomonium-like states. There is no working region for the light tetraquark currents, which implies that the light 0~＋- state may not exist below 2GeV.展开更多
We present a concise review of the vector charmonium state ψ(4230), which was originally labelled as Y(4260)in the literature. As one of the earliest candidates for a quantum chromodynamics exotic states, its interpr...We present a concise review of the vector charmonium state ψ(4230), which was originally labelled as Y(4260)in the literature. As one of the earliest candidates for a quantum chromodynamics exotic states, its interpretation has initiated various ideas about possible manifestations of non-perturbative mechanisms in the charmonium mass regime. In this short article we briefly review the experimental status of ψ(4230) and discuss possible theoretical interpretations. We will focus on four broadly investigated scenarios, i.e., tetraquark, hybrid, hadro-quarkonium,and hadronic molecule, and highlight the key issues based on these approaches. Crucial experimental observables,e.g., mass position, lineshapes, di-lepton decay width Γ_(ee), production rates in B meson decays, dominant hadronic decay patterns, and the potential 1^(-+)and 0^(--)exotic partners, are assessed, which can provide crucial structure information for understanding this mysterious state.展开更多
The exploratory synthesis and structural characterization of twodimensional(2D)honeycomb structured Ru-based compounds are key focuses in inorganic materials research,due to the various exotic electronic states arisin...The exploratory synthesis and structural characterization of twodimensional(2D)honeycomb structured Ru-based compounds are key focuses in inorganic materials research,due to the various exotic electronic states arising from the interplay of electron correlations and spinorbit coupling.Among these compounds,α-RuCl_(3) and RuBr_(3) are considered as the most promising candidates for quantum spin liquid(QSL)materials[1–3].As a homolog,α-RuI3 has attracted significant interest,but it still remains relatively unexplored.Recently,it was synthesized by high-temperature and high-pressure solid-state reaction,but reported to be different crystal structures by independent groups.Ni et al.and Nawa et al.considerα-RuI3 to be R-3(3R)and P-31c(2H)space group,respectively[4,5].Both structures have typical 2D characteristics,in which the edge-sharing RuI6 octahedra form honeycomb layers stacked along the c-axis.The primary difference lies in that the honeycomb layers stack in ABCABC mode in the 3R phase,while in ABAB mode in the 2H phase(Fig.S1).Yang et al.discussed the stability of 3R and 2H polymorphs in terms of the total energies and dynamics,finding both structures are stable.However,the total energy of the 2H phase is slightly higher,2.58 meV than that of the 3R analog[6].When it comes to the conductivity behaviour,α-RuCl3 andα-RuBr_(3) are semiconductors as normally observed in QSL materials.In contrast,α-RuI_(3) exhibits metallic response.In 2D materials,the band structure may be drastically modified by altering the stacking order[7].Hence,determining the crystal structure ofα-RuI_(3) is urgently required,which is a key step in comprehensive and in-depth analysis of its physical properties.展开更多
One important issue in current condensed matter physics is the search of quantum spin liquid(QSL),an exotic magnetic state with strongly-fluctuating and highly-entangled spins down to zero temperature without static o...One important issue in current condensed matter physics is the search of quantum spin liquid(QSL),an exotic magnetic state with strongly-fluctuating and highly-entangled spins down to zero temperature without static order.However,there is no consensus on the existence of a QSL state in any real material so far,due to inevitable disorder and intricate competing exchange interactions on frustrated spin lattices.Here we report systematic heat transport measurements on a honeycomb-lattice compound BaCo_(2)(AsO_(4))_(2),which manifests magnetic order in zero field.In a narrow in-plane field range after the magnetic order is nearly suppressed,in both perpendicular and parallel to the zigzag direction,a finite residual linear term of thermal conductivity is clearly observed,which is attributed to mobile fermionic excitations.In addition,the spin-phonon scattering rate exhibits a T-linear behavior when the order disappears.These observations suggest a partial QSL state with gapless spinon excitations in BaCo_(2)(AsO_(4))_(2),that emerges when a portion of the spins remains ordered,and vanishes as the spins become progressively polarized.展开更多
The possible place to search for exotic states in J/ψ hadronic decays is in J/ψ →ρρπ. Because of the symmetry of identical particle and the symmetry of isospin, the physical analysis on this channel is quite com...The possible place to search for exotic states in J/ψ hadronic decays is in J/ψ →ρρπ. Because of the symmetry of identical particle and the symmetry of isospin, the physical analysis on this channel is quite complicated. In this paper, the method to use the partial wave analysis based on covariant helicity amplitude analysis to study the invariant mass spectrum of ρρπ and to find the evidence of exotic states in ρρπ spectrum is discussed. The decay amplitude for the decay sequence J/ψ→ρX, X →ρπ is given first. Then we discuss how to realize the identical particle symmetry and the isospin symmetry in the decay amplitude, which is the key point in the analysis of this channel. Then the total decay amplitude of this channel including all decay components is given. After that, how to identify the exotic states in the ρρπ spectrum is discussed. What is discussed in this paper is the theoretical basis on experimentally searching for exotic states at BEPC/BES.展开更多
With its unique data samples at energies of 3.8-4.6 GeV, the BESIII experiment made a significant contribution to the study of charmonium and charinonium-like states, i.e., the XYZ states. We review the results for ob...With its unique data samples at energies of 3.8-4.6 GeV, the BESIII experiment made a significant contribution to the study of charmonium and charinonium-like states, i.e., the XYZ states. We review the results for observations of the Zc（3900） and Zc（4020） states, the X（3872） in e^＋e^- annihilation, and charmonium ψ（13D2） state, as well as measurements of the cross-sections of ωχcJ and ηJ/ψ, and the search for e^＋e^-→γχcJ and γY（4140）. We also present data from BESIII that may further strengthen the study of the XYZ and conventional charmonium states, and discuss perspectives on future experiments.展开更多
In this work, we use the Born-Oppenheimer approximation, where the potential between atoms can be approximated as a function of distance between the two nuclei, to study the four-quark bound states. By this approximat...In this work, we use the Born-Oppenheimer approximation, where the potential between atoms can be approximated as a function of distance between the two nuclei, to study the four-quark bound states. By this approximation, Heitler and London calculated the spectrum of the hydrogen molecule, which includes two protons （heavy） and two electrons （light）. Cenerally, the observed exotic mesons Zb（10610）, ZD（10650）, Zc（3900） and Zc（4020） （Zc（4025）） may be molecular states made of two physical mesons and/or diquark-anti-diquark structures. Analogous to the Heitler-London method for calculating the mass of the hydrogen molecule, we investigate whether there exist energy minima for these two structures. Contrary to the hydrogen molecule case where only the spin-triplet possesses an energy minimum, there exist minima for both of these states. This implies that both molecule and tetraquark states can be stable objects. Since they have the same quantum numbers, however, the two states may mix to result in the physical states. A consequence would be that partner exotic states co-existing with ZD（10610）, Zb（]0650）, Zc（3900） and Zc（4020） （Zc（4025）） are predicted and should be experimentally observed.展开更多
Very recently, the D0 collaboration has reported the observation of a narrow structure, X（5568）, in the decay process X（5568）→ Bs^0π^±using the 10.4fb^-1 data of pp collision at √s= 1.96 TeV. This structur...Very recently, the D0 collaboration has reported the observation of a narrow structure, X（5568）, in the decay process X（5568）→ Bs^0π^±using the 10.4fb^-1 data of pp collision at √s= 1.96 TeV. This structure is of great interest since it is the first hadronic state with four different valence quark flavors, b, s, u, d. In this work,we investigate tetraquarks with four different quark flavors. Based on the diquark-antidiquark scheme, we study the spectroscopy of the tetraquarks with one heavy bottom/charm quark and three light quarks. We find that the lowest-lying S-wave state, a tetraquark with the flavor [su][bd] and the spin-parity J^P= 0^＋, is about 150 MeV higher than the X（5568）. Further detailed experimental and theoretical studies of the spectrum, production and decays of tetraquark states with four different flavors are vital to gain a better understanding of the nature and classification of hadron exotic states.展开更多
We study the mass spectra of D-wave excited cscs tetraquark states with J^(PC)=1^(++)and 1^(+-)in both symmetric 6cs@6cs and antisymmetric 3cs@3cs color configurations using the QCD sum rule method.We construct the D-...We study the mass spectra of D-wave excited cscs tetraquark states with J^(PC)=1^(++)and 1^(+-)in both symmetric 6cs@6cs and antisymmetric 3cs@3cs color configurations using the QCD sum rule method.We construct the D-wave diquark-antidiquark type of cscs tetraquark interpolating currents in various excitation structures with(L_(λ),Lp{p_(1),p_(2)})=(2,0(0,0),(1,1(1,0),(1,1(0,1),(0,2(1,1),(0,2(2,0),(0,2(0,2).Our results support the interpretation of the recently observed X(4685)resonance as a D-wave cscs tetraquark state with JPC-1++in the(2,O(0,O))or(0,2(2,O))excitation mode,although some other possible excitation structures cannot be excluded exhaustively within theoretical errors.Moreover,our results provide the mass relations 6_(ρρ)<3_(λλ)<3_(λρ)<3_(ρρ)and 6pp<3au<6aa<3pp for the positive and negative C-parity D-wave cscs tetraquarks,respectively.We suggest searching for these possible D-wave cscs tetraquarks in both the hidden-charm channels J/o and nc,as well as open-cham channes such as D_(s)D_(x)nd D_(s)D_(s1).展开更多
Electro-production of several pentaquark states is investigated in this study.The eSTARlight package is adapted to study the electro-production of J/ψand γ(1S)via pentaquark P_(c)and P_(b)resonance channels in ep→...Electro-production of several pentaquark states is investigated in this study.The eSTARlight package is adapted to study the electro-production of J/ψand γ(1S)via pentaquark P_(c)and P_(b)resonance channels in ep→eJ/ψp and ep→eγ(1S)p scattering processes at the proposed electron-ion colliders(EICs).The results obtained in this study are compared to those of non-resonance t-channels,which are described in the pomeron exchange model developed in our studies.Some pseudo-rapidity and rapidity distributions of J/ψand γ(1S)are presented for the proposed EICs,including EicC and EIC-US.It is found that EicC is a good platform to identify P_(b) states in the future.展开更多
In this study,we evaluated the mass spectra of the prospective 0^(--) hidden-charm and hidden-bottom tetraquark states in molecular configuration via QCD sum rules.In our calculation,the nonperturbative condensate con...In this study,we evaluated the mass spectra of the prospective 0^(--) hidden-charm and hidden-bottom tetraquark states in molecular configuration via QCD sum rules.In our calculation,the nonperturbative condensate contributions are considered up to dimension eight in operator product expansion.It is found that there could exist 4possible 0^(--) hidden-charm tetraquark states with masses(4.68±0.07),(4.22±0.09),(4.53±0.09),and(4.26±0.13) GeV.Their corresponding hidden-bottom partners are found lying at(11.04±0.10),(10.71±0.12),(11.09±0.10),and(11.82±0.14) GeV,respectively.The possible tetraquark decay modes were analyzed,which are expected to be measured in BESⅢ,BELLEⅡ,and LHCb experiments.展开更多
The three lowest-lying r states,ie,r(1S),T(2S),and r(35),composed of b pairs and below the BB threshold,provide a good platform for the researches of hadronic physics and physics beyond the Standard Model.They can be ...The three lowest-lying r states,ie,r(1S),T(2S),and r(35),composed of b pairs and below the BB threshold,provide a good platform for the researches of hadronic physics and physics beyond the Standard Model.They can be produced directly in ete--colliding experiments,such as CLEO,Babar,and Belle,with low continuum backgrounds.In these experiments,many measurements of the exclusive r(1S)and r(2S)decays into light hadrons,which shed light on the"80%rule"for the Okubo-Zweig-lizuka suppressed decays in the bottomonium sector,were carried out.Meanwhile,many studies of the charmonium and bottomonium productions in r(1S,2S,3S)decays were performed,to distinguish different Quantum Chromodynamics(QCD)models.Besides,exotic states and new physics were also extensively explored in r(1S,2S,3S)decays at CLEO,BaBar,and Bell.The r(1S,2S,3S)states can also be produced in p collisions and in ollisions involving heavy ions.The precision measurements of their cross sections and polarizations at the large hadron collider(LHC),especially in the CMS,ATLAS,and LHCb experiments,help to understand r production mechanisms in Pp collisions.The observation of the sequential r suppession in heavy ion collisions at CMS,LHCb,and ALICE is of great importance for verifying the quark-gluon plasma predicted by QCD.In this article,we review the experimental results on T(1S,2S,3S)at e+e-colliders and the LHC,and summarize their prospects at Belle II and the LHC.展开更多
The confirmation of charged charmonium-like states indicates that heavy quark molecules should exist. Here we discuss the possibility of a molecule state with ^PC=3^-＋. In a one-boson-exchange model investigation for...The confirmation of charged charmonium-like states indicates that heavy quark molecules should exist. Here we discuss the possibility of a molecule state with ^PC=3^-＋. In a one-boson-exchange model investigation for the S wave C=＋ D^＊D2^＊ states, one finds that the strongest attraction is in the case J= 3 and I=0 for both π and σ exchanges. Numerical analysis indicates that this hadronic bound state might exist if a phenomenological cutoff parameter around 2.3 GeV （1.5 GeV） is reasonable with a dipole （monopole） type form factor in the one-pion- exchange model. The cutoff for binding solutions may be reduced to a smaller value once the σ exchange contribution is included. If a state around the D^＊D2^＊ threshold （≈4472 MeV） in the channel J/ψω （P wave） is observed, the heavy quark spin symmetry implies that it is not ace meson and the jPC are likely to be 3^-＋.展开更多
We review the recent BESIII measurement of e＋e-→ππhc in which its line shape is studied between the center-of-mass energies of 3.9 to 4.42 GeV and an iso-vector charmonium-like state Zc（4020） is observed in the ...We review the recent BESIII measurement of e＋e-→ππhc in which its line shape is studied between the center-of-mass energies of 3.9 to 4.42 GeV and an iso-vector charmonium-like state Zc（4020） is observed in the invariant mass of 7rhc at the BESIII experiment. The charged Zc（4020）± is the second observed Zc state following Zc（3900）, while the Zc（4020）0 is the first observed neutral Zc state. The line shape of δ（e＋e-→ππhc）is also re-analyzed in view of searching for the Y state and the existence of the Y（4220） state is confirmed and compared with the previous work of the BESIII experiment.展开更多
We present severM possible hadronic states found in coupled-channel models within the on-shell approx- imation. The interaction potential is constructed as a sum of the tree-level Feynman diagrams calculated with the ...We present severM possible hadronic states found in coupled-channel models within the on-shell approx- imation. The interaction potential is constructed as a sum of the tree-level Feynman diagrams calculated with the effective Lagrangians. Based on the recent empirical data, we illustrate the possible existence of severM baryonic and mesonic states with definite quantum numbers in the model. We give their properties for the purpose of further study and discuss the potential of finding them in future experiments.展开更多
We study the contributions of intermediate bottomonium-like Zb states and the bottom meson loops in the heavy quark spin flip transitionsγ(4 S)→hb(1 P,2 P)π+π-.Depending on the constructive or destructive interfer...We study the contributions of intermediate bottomonium-like Zb states and the bottom meson loops in the heavy quark spin flip transitionsγ(4 S)→hb(1 P,2 P)π+π-.Depending on the constructive or destructive interferences between the Zb-exchange and the bottom meson loops mechanisms,we predict two possible branching ratios for each process:BRγ(4 S)→hb(1 P)π+π-≈(1.20.40.8×10^-6)or(0.5-0.20.5×10^-6),and BRγ(4 S)→(2 P)π+π-≈(7.1-1.1+1.7×10^-10)or(2.4-0.10.2×10^-10)).The contribution of the bottom meson loops is found to be considerably larger than that of the Zbexchange in the T(4 S)→hb(1 P)ππtransitions,while its decay rates are not comparable to those of heavy quark spin conservedγ(4 S)→γ(1 S,2 S)ππprocesses.We also predict the contribution of the charm meson loops in the branch fractions ofΨ(3 S,4 S)→hc(1 P)ππ.展开更多
Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)...Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)has been proposed.It will be constructed based on an upgraded heavy-ion accelerator,High Intensity heavy-ion Accelerator Facility(HIAF)which is currently under construction,together with a new electron ring.The proposed collider will provide highly polarized electrons(with a po-larization of 80%)and protons(with a polarization of 70%)with variable center of mass energies from 15 to 20 GeV and the luminosity of(2–3)×1033 cm^(−2)·s^(−1).Polarized deuterons and Helium-3,as well as unpolarized ion beams from Carbon to Uranium,will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region,including 3D tomography of nucleon;the partonic structure of nuclei and the parton interaction with the nuclear environment;the exotic states,especially those with heavy flavor quark contents.In addition,issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC.In order to achieve the above-mentioned physics goals,a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe.The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States.The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.展开更多
文摘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.On the one hand,the structure of known exotic candidates is a fundamental open issue addressed widely by scientists.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.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).We address the effort of searching for exotic narrow N∗and Z states in light quark sector.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.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.
基金Supported by National Natural Science Foundation of China (10575002,10721063,10521003,10625524)
文摘The J/ψ hadronic decays provide good laboratory to search for the hybrid states with exotic quantum numbers. A full Partial Wave Analysis （PWA） is performed to the generated Monte Carlo J/ψ→ ρηπ data, based on the design of BESⅢ detector, to study the sensitivity of searching for a possible exotic state at BESⅢ.
基金Supported by National Natural Science Foundation of China (11075004, 11021092)the Ministry of Science and Technology of China (2009CB825200)
文摘We study possible exotic J^（PC）=0~＋- states using tetraquark interpolating currents with the QCD sum rule approach. The extracted masses are around 4.85GeV for the charmonium-like states and 11.25 GeV for the bottomonium-like states. There is no working region for the light tetraquark currents, which implies that the light 0~＋- state may not exist below 2GeV.
基金supported in part by the National Natural Science Foundation of China (Grant Nos.12375073 and 12235018)。
文摘We present a concise review of the vector charmonium state ψ(4230), which was originally labelled as Y(4260)in the literature. As one of the earliest candidates for a quantum chromodynamics exotic states, its interpretation has initiated various ideas about possible manifestations of non-perturbative mechanisms in the charmonium mass regime. In this short article we briefly review the experimental status of ψ(4230) and discuss possible theoretical interpretations. We will focus on four broadly investigated scenarios, i.e., tetraquark, hybrid, hadro-quarkonium,and hadronic molecule, and highlight the key issues based on these approaches. Crucial experimental observables,e.g., mass position, lineshapes, di-lepton decay width Γ_(ee), production rates in B meson decays, dominant hadronic decay patterns, and the potential 1^(-+)and 0^(--)exotic partners, are assessed, which can provide crucial structure information for understanding this mysterious state.
基金supported by the National Natural Science Foundation of China(No.22090041)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2017ZT07C069)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2022B1515120014)the Natural Science Foundation of Zhejiang Province(No.LQ21A040010).
文摘The exploratory synthesis and structural characterization of twodimensional(2D)honeycomb structured Ru-based compounds are key focuses in inorganic materials research,due to the various exotic electronic states arising from the interplay of electron correlations and spinorbit coupling.Among these compounds,α-RuCl_(3) and RuBr_(3) are considered as the most promising candidates for quantum spin liquid(QSL)materials[1–3].As a homolog,α-RuI3 has attracted significant interest,but it still remains relatively unexplored.Recently,it was synthesized by high-temperature and high-pressure solid-state reaction,but reported to be different crystal structures by independent groups.Ni et al.and Nawa et al.considerα-RuI3 to be R-3(3R)and P-31c(2H)space group,respectively[4,5].Both structures have typical 2D characteristics,in which the edge-sharing RuI6 octahedra form honeycomb layers stacked along the c-axis.The primary difference lies in that the honeycomb layers stack in ABCABC mode in the 3R phase,while in ABAB mode in the 2H phase(Fig.S1).Yang et al.discussed the stability of 3R and 2H polymorphs in terms of the total energies and dynamics,finding both structures are stable.However,the total energy of the 2H phase is slightly higher,2.58 meV than that of the 3R analog[6].When it comes to the conductivity behaviour,α-RuCl3 andα-RuBr_(3) are semiconductors as normally observed in QSL materials.In contrast,α-RuI_(3) exhibits metallic response.In 2D materials,the band structure may be drastically modified by altering the stacking order[7].Hence,determining the crystal structure ofα-RuI_(3) is urgently required,which is a key step in comprehensive and in-depth analysis of its physical properties.
基金funded by the National Natural Science Foundations of China(Grant Nos.12034004 and 12174064)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+2 种基金the Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300104)supported by U.S.DOE BES DE-SC0012311the Robert A.Welch Foundation under Grant No.C-1839,respectively(P.D.)。
文摘One important issue in current condensed matter physics is the search of quantum spin liquid(QSL),an exotic magnetic state with strongly-fluctuating and highly-entangled spins down to zero temperature without static order.However,there is no consensus on the existence of a QSL state in any real material so far,due to inevitable disorder and intricate competing exchange interactions on frustrated spin lattices.Here we report systematic heat transport measurements on a honeycomb-lattice compound BaCo_(2)(AsO_(4))_(2),which manifests magnetic order in zero field.In a narrow in-plane field range after the magnetic order is nearly suppressed,in both perpendicular and parallel to the zigzag direction,a finite residual linear term of thermal conductivity is clearly observed,which is attributed to mobile fermionic excitations.In addition,the spin-phonon scattering rate exhibits a T-linear behavior when the order disappears.These observations suggest a partial QSL state with gapless spinon excitations in BaCo_(2)(AsO_(4))_(2),that emerges when a portion of the spins remains ordered,and vanishes as the spins become progressively polarized.
基金The project supported in part by National Natural Science Foundation of China under Grant Nos, 10575002, 10421503, 10491306, and 10491300.Acknowledgments The authors acknowledge helpful discussions with H.Q Zheng and X.Y. Shen.
文摘The possible place to search for exotic states in J/ψ hadronic decays is in J/ψ →ρρπ. Because of the symmetry of identical particle and the symmetry of isospin, the physical analysis on this channel is quite complicated. In this paper, the method to use the partial wave analysis based on covariant helicity amplitude analysis to study the invariant mass spectrum of ρρπ and to find the evidence of exotic states in ρρπ spectrum is discussed. The decay amplitude for the decay sequence J/ψ→ρX, X →ρπ is given first. Then we discuss how to realize the identical particle symmetry and the isospin symmetry in the decay amplitude, which is the key point in the analysis of this channel. Then the total decay amplitude of this channel including all decay components is given. After that, how to identify the exotic states in the ρρπ spectrum is discussed. What is discussed in this paper is the theoretical basis on experimentally searching for exotic states at BEPC/BES.
基金Supported in part by National Key R&D Program of China under Contracts No.2020YFA0406400the National Natural Science Foundation of China(11722540,12075019)the Fundamental Research Funds for the Central Universities。
基金Acknowledgements This work was supported in part by the National Natural Science Foundation of China （NSFC） under Grant Nos. 11235011 and 11475187 the Ministry of Science and Technology of China under Grant No. 2015CB856701, and the CAS Center for Excellence in Particle Physics （CCEPP）.
文摘With its unique data samples at energies of 3.8-4.6 GeV, the BESIII experiment made a significant contribution to the study of charmonium and charinonium-like states, i.e., the XYZ states. We review the results for observations of the Zc（3900） and Zc（4020） states, the X（3872） in e^＋e^- annihilation, and charmonium ψ（13D2） state, as well as measurements of the cross-sections of ωχcJ and ηJ/ψ, and the search for e^＋e^-→γχcJ and γY（4140）. We also present data from BESIII that may further strengthen the study of the XYZ and conventional charmonium states, and discuss perspectives on future experiments.
基金Supported by National Natural Science Foundation of China(11375128)
文摘In this work, we use the Born-Oppenheimer approximation, where the potential between atoms can be approximated as a function of distance between the two nuclei, to study the four-quark bound states. By this approximation, Heitler and London calculated the spectrum of the hydrogen molecule, which includes two protons （heavy） and two electrons （light）. Cenerally, the observed exotic mesons Zb（10610）, ZD（10650）, Zc（3900） and Zc（4020） （Zc（4025）） may be molecular states made of two physical mesons and/or diquark-anti-diquark structures. Analogous to the Heitler-London method for calculating the mass of the hydrogen molecule, we investigate whether there exist energy minima for these two structures. Contrary to the hydrogen molecule case where only the spin-triplet possesses an energy minimum, there exist minima for both of these states. This implies that both molecule and tetraquark states can be stable objects. Since they have the same quantum numbers, however, the two states may mix to result in the physical states. A consequence would be that partner exotic states co-existing with ZD（10610）, Zb（]0650）, Zc（3900） and Zc（4020） （Zc（4025）） are predicted and should be experimentally observed.
基金Supported by National Natural Science Foundation of China(11575110)Natural Science Foundation of Shanghai(15DZ2272100,15ZR1423100)+2 种基金China Postdoctoral Science FoundationOpen Project Program of State Key Laboratory of Theoretical Physics,Institute of Theoretical Physics,Chinese Academy of Sciences,China(Y5KF111CJ1)Scientific Research Foundation for Returned Overseas Chinese Scholars,State Education Ministry
文摘Very recently, the D0 collaboration has reported the observation of a narrow structure, X（5568）, in the decay process X（5568）→ Bs^0π^±using the 10.4fb^-1 data of pp collision at √s= 1.96 TeV. This structure is of great interest since it is the first hadronic state with four different valence quark flavors, b, s, u, d. In this work,we investigate tetraquarks with four different quark flavors. Based on the diquark-antidiquark scheme, we study the spectroscopy of the tetraquarks with one heavy bottom/charm quark and three light quarks. We find that the lowest-lying S-wave state, a tetraquark with the flavor [su][bd] and the spin-parity J^P= 0^＋, is about 150 MeV higher than the X（5568）. Further detailed experimental and theoretical studies of the spectrum, production and decays of tetraquark states with four different flavors are vital to gain a better understanding of the nature and classification of hadron exotic states.
基金Supported by the National Natural Science Foundation of China(12175318)the National Key R&D Program of China(2020YFA0406400)+1 种基金the Natural Science Foundation of Guangdong Province of China(2022A1515011922)the Fundamental Research Funds for the Central Universities。
文摘We study the mass spectra of D-wave excited cscs tetraquark states with J^(PC)=1^(++)and 1^(+-)in both symmetric 6cs@6cs and antisymmetric 3cs@3cs color configurations using the QCD sum rule method.We construct the D-wave diquark-antidiquark type of cscs tetraquark interpolating currents in various excitation structures with(L_(λ),Lp{p_(1),p_(2)})=(2,0(0,0),(1,1(1,0),(1,1(0,1),(0,2(1,1),(0,2(2,0),(0,2(0,2).Our results support the interpretation of the recently observed X(4685)resonance as a D-wave cscs tetraquark state with JPC-1++in the(2,O(0,O))or(0,2(2,O))excitation mode,although some other possible excitation structures cannot be excluded exhaustively within theoretical errors.Moreover,our results provide the mass relations 6_(ρρ)<3_(λλ)<3_(λρ)<3_(ρρ)and 6pp<3au<6aa<3pp for the positive and negative C-parity D-wave cscs tetraquarks,respectively.We suggest searching for these possible D-wave cscs tetraquarks in both the hidden-charm channels J/o and nc,as well as open-cham channes such as D_(s)D_(x)nd D_(s)D_(s1).
基金National Natural Science Foundation of China(11975278,11405222)Key Research Program of the Chinese Academy of Sciences(XDPB09)。
文摘Electro-production of several pentaquark states is investigated in this study.The eSTARlight package is adapted to study the electro-production of J/ψand γ(1S)via pentaquark P_(c)and P_(b)resonance channels in ep→eJ/ψp and ep→eγ(1S)p scattering processes at the proposed electron-ion colliders(EICs).The results obtained in this study are compared to those of non-resonance t-channels,which are described in the pomeron exchange model developed in our studies.Some pseudo-rapidity and rapidity distributions of J/ψand γ(1S)are presented for the proposed EICs,including EicC and EIC-US.It is found that EicC is a good platform to identify P_(b) states in the future.
基金Supported in part by the National Natural Science Foundation of China(12247113)the Project funded by China Postdoctoral Science Foundation (2022M723117)the Specific Fund of Fundamental Scientific Research Operating Expenses for Undergraduate Universities in Liaoning Province,China (2024)。
文摘In this study,we evaluated the mass spectra of the prospective 0^(--) hidden-charm and hidden-bottom tetraquark states in molecular configuration via QCD sum rules.In our calculation,the nonperturbative condensate contributions are considered up to dimension eight in operator product expansion.It is found that there could exist 4possible 0^(--) hidden-charm tetraquark states with masses(4.68±0.07),(4.22±0.09),(4.53±0.09),and(4.26±0.13) GeV.Their corresponding hidden-bottom partners are found lying at(11.04±0.10),(10.71±0.12),(11.09±0.10),and(11.82±0.14) GeV,respectively.The possible tetraquark decay modes were analyzed,which are expected to be measured in BESⅢ,BELLEⅡ,and LHCb experiments.
基金We would like to thank Prof.Zhen Hu for fruitful discussions.This work was supported by the National Natural Science Foundation of China under Grant Nos.11575017,11761141009,11975076,and 11661141008the National Key R&D Program of China under the contract No.2018YFA0403902the CAS Center for Excellence in Particle Physics(CCEPP).
文摘The three lowest-lying r states,ie,r(1S),T(2S),and r(35),composed of b pairs and below the BB threshold,provide a good platform for the researches of hadronic physics and physics beyond the Standard Model.They can be produced directly in ete--colliding experiments,such as CLEO,Babar,and Belle,with low continuum backgrounds.In these experiments,many measurements of the exclusive r(1S)and r(2S)decays into light hadrons,which shed light on the"80%rule"for the Okubo-Zweig-lizuka suppressed decays in the bottomonium sector,were carried out.Meanwhile,many studies of the charmonium and bottomonium productions in r(1S,2S,3S)decays were performed,to distinguish different Quantum Chromodynamics(QCD)models.Besides,exotic states and new physics were also extensively explored in r(1S,2S,3S)decays at CLEO,BaBar,and Bell.The r(1S,2S,3S)states can also be produced in p collisions and in ollisions involving heavy ions.The precision measurements of their cross sections and polarizations at the large hadron collider(LHC),especially in the CMS,ATLAS,and LHCb experiments,help to understand r production mechanisms in Pp collisions.The observation of the sequential r suppession in heavy ion collisions at CMS,LHCb,and ALICE is of great importance for verifying the quark-gluon plasma predicted by QCD.In this article,we review the experimental results on T(1S,2S,3S)at e+e-colliders and the LHC,and summarize their prospects at Belle II and the LHC.
基金Supported by National Natural Science Foundation of China(11275115)Shandong Province Natural Science Foundation(ZR2010AM023)SRF for ROCS,SEM,and Independent Innovation Foundation of Shandong University
文摘The confirmation of charged charmonium-like states indicates that heavy quark molecules should exist. Here we discuss the possibility of a molecule state with ^PC=3^-＋. In a one-boson-exchange model investigation for the S wave C=＋ D^＊D2^＊ states, one finds that the strongest attraction is in the case J= 3 and I=0 for both π and σ exchanges. Numerical analysis indicates that this hadronic bound state might exist if a phenomenological cutoff parameter around 2.3 GeV （1.5 GeV） is reasonable with a dipole （monopole） type form factor in the one-pion- exchange model. The cutoff for binding solutions may be reduced to a smaller value once the σ exchange contribution is included. If a state around the D^＊D2^＊ threshold （≈4472 MeV） in the channel J/ψω （P wave） is observed, the heavy quark spin symmetry implies that it is not ace meson and the jPC are likely to be 3^-＋.
基金Supported by Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts No.U1332201National Natural Science Foundation of China(NSFC)under Contracts No.11475207
文摘We review the recent BESIII measurement of e＋e-→ππhc in which its line shape is studied between the center-of-mass energies of 3.9 to 4.42 GeV and an iso-vector charmonium-like state Zc（4020） is observed in the invariant mass of 7rhc at the BESIII experiment. The charged Zc（4020）± is the second observed Zc state following Zc（3900）, while the Zc（4020）0 is the first observed neutral Zc state. The line shape of δ（e＋e-→ππhc）is also re-analyzed in view of searching for the Y state and the existence of the Y（4220） state is confirmed and compared with the previous work of the BESIII experiment.
基金Supported by National Natural Science Foundation of China(11347146,11275235,11175220)
文摘We present severM possible hadronic states found in coupled-channel models within the on-shell approx- imation. The interaction potential is constructed as a sum of the tree-level Feynman diagrams calculated with the effective Lagrangians. Based on the recent empirical data, we illustrate the possible existence of severM baryonic and mesonic states with definite quantum numbers in the model. We give their properties for the purpose of further study and discuss the potential of finding them in future experiments.
基金Supported in part by the Fundamental Research Funds for the Central Universities(FRF-BR-19-001A)the National Natural Science Foundation of China(11975028)
文摘We study the contributions of intermediate bottomonium-like Zb states and the bottom meson loops in the heavy quark spin flip transitionsγ(4 S)→hb(1 P,2 P)π+π-.Depending on the constructive or destructive interferences between the Zb-exchange and the bottom meson loops mechanisms,we predict two possible branching ratios for each process:BRγ(4 S)→hb(1 P)π+π-≈(1.20.40.8×10^-6)or(0.5-0.20.5×10^-6),and BRγ(4 S)→(2 P)π+π-≈(7.1-1.1+1.7×10^-10)or(2.4-0.10.2×10^-10)).The contribution of the bottom meson loops is found to be considerably larger than that of the Zbexchange in the T(4 S)→hb(1 P)ππtransitions,while its decay rates are not comparable to those of heavy quark spin conservedγ(4 S)→γ(1 S,2 S)ππprocesses.We also predict the contribution of the charm meson loops in the branch fractions ofΨ(3 S,4 S)→hc(1 P)ππ.
文摘Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)has been proposed.It will be constructed based on an upgraded heavy-ion accelerator,High Intensity heavy-ion Accelerator Facility(HIAF)which is currently under construction,together with a new electron ring.The proposed collider will provide highly polarized electrons(with a po-larization of 80%)and protons(with a polarization of 70%)with variable center of mass energies from 15 to 20 GeV and the luminosity of(2–3)×1033 cm^(−2)·s^(−1).Polarized deuterons and Helium-3,as well as unpolarized ion beams from Carbon to Uranium,will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region,including 3D tomography of nucleon;the partonic structure of nuclei and the parton interaction with the nuclear environment;the exotic states,especially those with heavy flavor quark contents.In addition,issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC.In order to achieve the above-mentioned physics goals,a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe.The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States.The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.
