The transverse single-spin asymmetry forρ^(0) production in semi-inclusive deep inelastic scattering was recently reported by the COMPASS Collaboration.Using the Sivers function extracted from pion and kaon productio...The transverse single-spin asymmetry forρ^(0) production in semi-inclusive deep inelastic scattering was recently reported by the COMPASS Collaboration.Using the Sivers function extracted from pion and kaon productions,we perform a calculation of the Sivers asymmetry within the transverse momentum-dependent factorization.Our results are consistent with the COMPASS data,supporting the universality of the Sivers function in the semi-inclusive deep inelastic scattering process for different final-state hadrons within current experimental uncertainties.While different parametrizations of the Sivers function from global analyses allow describing the data equally well,we obtain very different predictions on the Sivers asymmetry ofρand K^(*)productions at electron-ion colliders,which therefore are expected to provide further constraints.展开更多
Pure leptonic decays of D~*0)(B_^(*s),B_d~*)→l^+l^- and D^(±*)(D_s~*,B^(*+),B_c~*)→lν_l are investigated.The hadronic contributions such as D^0→D^(*0)γ→μ^+μ^- are also explored.We then obtain the updated ...Pure leptonic decays of D~*0)(B_^(*s),B_d~*)→l^+l^- and D^(±*)(D_s~*,B^(*+),B_c~*)→lν_l are investigated.The hadronic contributions such as D^0→D^(*0)γ→μ^+μ^- are also explored.We then obtain the updated branching fractions of the pseudoscalar mesons to lepton pairs are modified by a factor of few percentages.Specifically,the Br(B+→e^+ν_e)is reduced by a factor 13%.展开更多
Vorticities in heavy-ion collisions(HICs)are supposed to induce spin alignment and polarization phenomena of quarks and mesons.In this work,we analyze the spin alignment of vector mesonsϕandρinduced by rotation from ...Vorticities in heavy-ion collisions(HICs)are supposed to induce spin alignment and polarization phenomena of quarks and mesons.In this work,we analyze the spin alignment of vector mesonsϕandρinduced by rotation from quark dynamics in the framework of the Nambu-Jona-Lasinio(NJL)model.The rotating angular velocity induces mass splitting of spin components for vectorϕ,ρmesons M_(ϕ,ρ)(Ω)≃M_(ϕ,ρ)(Ω=0)−szΩ.This behavior contributes to the spin alignment of vector mesonsϕ,ρin an equilibrium medium and naturally explains the negative deviation ofρ00−1/3 for vector mesons.Incidentally,the positive deviation ofρ00−1/3 under the magnetic field can also be easily understood from quark dynamics.展开更多
To investigate the possible geometric structure of the proton,an improved stringy proton model is constructed beyond the smallest distance approximation and treats the constituent(up and down)quark-initiated gluon tub...To investigate the possible geometric structure of the proton,an improved stringy proton model is constructed beyond the smallest distance approximation and treats the constituent(up and down)quark-initiated gluon tubes separately,where the constituent quarks are connected by gluon tubes which merge at the Fermat point of the quark triangle.The exclusive diffractive vector meson production process in electron-proton deep inelastic scattering is used to test the stringy structure of the proton.We calculate the coherent and incoherent differential cross sections of the exclusive diffractive J/Ψphotoproduction in the framework of Color Glass Condensate.The results show that our calculations are in good agreement with HERA data.Especially,our results give a better description of the HERA data at small t as compared to the ones from the hot spot model where the constituent quarks are independently distributed in the proton.Meanwhile,the radius of the proton resulting from the improved stringy proton model is coincident with the one from fitting to the data from GlueX Collaboration at Jefferson Lab,which indicates that the predictive power of the stringy proton model is significantly improved once it goes beyond the smallest distance approximation and treats the constituent quarks separately,instead of using the same profile for the up and down quarks initiated gluon tubes.Moreover,we assume that the transverse shape of the gluon tube satisfies Gaussian distribution,and explore the distribution width of the individual gluon tubes.We find an interesting result that the up quark-initiated gluon tube seems to have a larger distribution width than the down quarkinitiated gluon tube,which is favored by the HERA data.展开更多
Based on Pomeron exchange model, elastic production of vector meson in electro-proton interaction is investigated with both linear and non-linear Pomeron trajectory. A numerical calculation for J/psi production is per...Based on Pomeron exchange model, elastic production of vector meson in electro-proton interaction is investigated with both linear and non-linear Pomeron trajectory. A numerical calculation for J/psi production is performed. The effect of the energy scale so and photon virtuality Q(2) on differential cross section are also predicted. A good agreement with experimental data is obtained. Our conclusions are that the Pomeron exchange model is a successful description of J/psi electro-production, the dependence of the differential cross sections on Q2 is negligible, the linear trajectory is a good approximation to non-linearity of the Pomeron trajectory, and the value of the energy scale parameter so is dependent on the momentum transfer, namely its effect is moderate at low momentum transfer but it causes no difference at high momentum transfer vertical bar t vertical bar >= 1.25 GeV2.展开更多
Based on the quark-gluon contents of nucleon and strongly believing that the force mediators,Pomeronand its counterpart in the conventional approach of Regge theory,for high energy diffractive process would be the ten...Based on the quark-gluon contents of nucleon and strongly believing that the force mediators,Pomeronand its counterpart in the conventional approach of Regge theory,for high energy diffractive process would be the tensorglueball and Odderon respectively,we discuss photo-production of vector meson φ off the deuteron at energy less than 3GeV in the QCD inspired model in which the quark gluon degrees of freedom and glueball,Odderon exchange are takeninto account.A calculation is performed for γ + D →φ + D,and the theoretical predictions of the differential crosssection dσ^(γD)) /dt,are presented and compared with available experimental data.Our QCD inspired model reproducesdata quite well in the whole range of the experimental measurements up to |t| ■0.4 GeV.Our results can be used toextract γn→φn data,which cannot be measured in experiment.展开更多
Vector meson mass values are studied at finite chemical potential and temperature in lattice QCD with lattice size of 24 × 122× 6 using two flavors of staggered quarks. The investigation focuses on the chang...Vector meson mass values are studied at finite chemical potential and temperature in lattice QCD with lattice size of 24 × 122× 6 using two flavors of staggered quarks. The investigation focuses on the change of the vector meson mass in the critical region close to T c with two different types of chemical potentials switched on: the isoscalar chemical potential μS and its isovector counterpart μV. It is found that the vector meson mass increases in the QGP phase with both chemical potentials and decreases with μS in the confinement phase.展开更多
In this article,we study the vector meson transitions among the charmonium and bottomonium states with the heavy quark effective theory in a systematic way,and make predictions for the ratios among the vector meson de...In this article,we study the vector meson transitions among the charmonium and bottomonium states with the heavy quark effective theory in a systematic way,and make predictions for the ratios among the vector meson decay widths of a special multiplet to another multiplet.The predictions can be confronted with the experimental data in the future.展开更多
In this paper,a formalism is presented for the helicity amplitude analysis of the decays Ψ(2S)→γ_(1)χ_(c)J,χ_(c)J→γ_(2)V(V=p^(0),φ,ω)(subscripts 1 and 2 are used to distinguish the two radiative photons),and ...In this paper,a formalism is presented for the helicity amplitude analysis of the decays Ψ(2S)→γ_(1)χ_(c)J,χ_(c)J→γ_(2)V(V=p^(0),φ,ω)(subscripts 1 and 2 are used to distinguish the two radiative photons),and the polarization expressions of the P-wave charmonia χ_(c)J and the vector mesons p^(0),φ,ω for experimental measurements at an electron-positron collider.In addition,we derive formulae for the angular distributions of χ_(c1,2)→γV to extract the degree of transverse polarization P_(T) of e^(+)e^(-)pairs with symmetric beam energy as well as the ratios of two helicity amplitudes x(in χ_(c1) decays)and x,y(in χ_(c2) decays),which represent the relative magnitudes of transverse to longitudinal polarization amplitude.The results are validated by Monte Carlo simulation.Finally,the statistical sensitivity of P_(T),x,and y are estimated based on the large Ψ(2S)data samples collected at current and proposed future e^(+)e^(-)colliderexperiments.展开更多
The global spin alignment of vector mesons has been observed by the STAR collaboration at the Relativistic Heavy Ion Collider(RHIC)at Brookhaven National Laboratory(BNL).It provides a unique opportunity to probe the c...The global spin alignment of vector mesons has been observed by the STAR collaboration at the Relativistic Heavy Ion Collider(RHIC)at Brookhaven National Laboratory(BNL).It provides a unique opportunity to probe the correlation between the po-larized quark and antiquark in the strongly coupled quark-gluon plasma(sQGP)produced in relativistic heavy ion collisions,opening a new window to explore the properties of sQGP.In addition,spin alignments of vector mesons have also been observed in other high-energy particle collisions such as e^(+)e^(−)annihilations at high energies where hadron production is dominated by quark fragmentation mechanism.The results obtained are quite different from those obtained in heavy ion collisions where quark coalescence/combination mechanism dominates suggesting strong dependence on hadronization mechanisms.So comprehensive studies in different hadronization processes are needed.In this article,we present a brief review of theoretical and experimen-tal advances in the study of vector meson’s spin alignments in a variety of high-energy particle collisions,with emphasis on hadronization mechanisms.展开更多
The strong and electromagnetic corrections toρ-ωmixing are calculated using an SU(2)version of resonance chiral theory up to next-to-leading orders in 1/N_(C)expansion,respectively.Up to our accuracy,the effect of t...The strong and electromagnetic corrections toρ-ωmixing are calculated using an SU(2)version of resonance chiral theory up to next-to-leading orders in 1/N_(C)expansion,respectively.Up to our accuracy,the effect of the momentum dependence ofρ-ωmixing is incorporated due to the inclusion of loop contributions.We analyze the impact ofρ-ωmixing on the pion vector form factor by performing numerical fit to the data extracted from e^(+)e^(-)→π^(+)π^(-)andτ→ν_(τ)2π,while the decay width ofω→π^(+)π^(-)is taken into account as a constraint.It is found that the momentum dependence is significant in a good description of the experimental data.In addition,based on the fitted values of the involved parameters,we analyze the decay width ofω→π^(+)π^(-),which turns out to be highly dominated by theρ-ωmixing effect.展开更多
Based on Pomeron exchange model, J/ψ and φ production in electro-proton interaction are investigated with both linear and non-linear Pomeron trajectory. The experimental differential cross sections measured as a fun...Based on Pomeron exchange model, J/ψ and φ production in electro-proton interaction are investigated with both linear and non-linear Pomeron trajectory. The experimental differential cross sections measured as a function of the kinematic variable Q^2,W and t are reproduced successfully in the model. Our conclusions are that the Pomeron exchange model is a successful description of J/ψ and φ electro-productions on the proton, and that the linear trajectory is a good approximation to non-linearity of the Pomeron trajectory.展开更多
Based on the generalized vector meson dominance model in QCD, we study photoproduction of vector meson T off the proton by use of the QCD inspired model in which the contributions from quark-quark, gluon-gluon, and qu...Based on the generalized vector meson dominance model in QCD, we study photoproduction of vector meson T off the proton by use of the QCD inspired model in which the contributions from quark-quark, gluon-gluon, and quark-gluon interference term to observable are taken into consideration. Calculations are performed for total cross section σtot, differential cross section dσ/dt, ratio of the real part to imaginary part of forward scattering amplitude ρ, and nuclear slop parameter function β. The mediators of interactions between projectiles （the quark and antiquark pair fluctuated from the real the photon） and the proton target （three-quark system） are the tensor Glueball and Odderon instead of using the usual Pomeron exchange. The theoretical predictions for σtot （s） are consistent with the experimental data within error bars of the data. The data for dσ/dt, ρ, and β are urgently needed.展开更多
Holographic models that consider classical vector fields in a 5-d background provide effective descriptions for heavy vector meson spectra.This is true both in vacuum and a thermal medium,such as quark gluon plasma.Ho...Holographic models that consider classical vector fields in a 5-d background provide effective descriptions for heavy vector meson spectra.This is true both in vacuum and a thermal medium,such as quark gluon plasma.However,the manner in which these phenomenological models work is unclear.In particular,what is the role of the fifth dimension,and what is the relation between the holographic 5-d background and physical(4-d)heavy mesons?Hadrons,in contrast to leptons,are composite particles with some internal structure that depends on the energy at which they are observed.In this study,a static meson is represented by a heavy quark-antiquark pair with an interaction described by a Nambu Goto string existing in the same 5-d background that provides field solutions leading to masses and decay constants of charmonium states.The resulting interaction potential is linear for large distances,with a string tension consistent with the effective Cornell potential.Introducing temperature T in the background,it is found for the J/ψcase that there is a deconfining transition at some critical value of T.The obtained results indicate that the 5-d background effectively represents the internal structure of the(static)charmonium(quasi)states.展开更多
Measurements of ω photoproduction of the Crystal-Barrel/TAPS experiment at the ELSA accelerator of Bonn University are presented which used linearly polarized tagged photon beam from threshold to Eγ = 1700MeV. The a...Measurements of ω photoproduction of the Crystal-Barrel/TAPS experiment at the ELSA accelerator of Bonn University are presented which used linearly polarized tagged photon beam from threshold to Eγ = 1700MeV. The azimuthal asymmetries ∑and ∑πindicate s-channel resonance contributions on top of the established t-channel exchange processes. These findings are further enhanced by a very first measurement of the G-asymmetry which, in addition to the polarized photon beam, also requires a longitudinally polarized proton target. An intuitive interpretation of the specific sensitivity of the azimuthal asymmetries to the reaction mechanisms involved is given.展开更多
In this study,we continue an investigation of the semileptonic decays B_(s)→D_(s)^(*)lve.First,we derive the moments of the D_(s)^(*)-meson longitudinal leading-twist light-cone distribution amplitude (LCDA) based on...In this study,we continue an investigation of the semileptonic decays B_(s)→D_(s)^(*)lve.First,we derive the moments of the D_(s)^(*)-meson longitudinal leading-twist light-cone distribution amplitude (LCDA) based on QCD sum rules within the background field theory framework.Considering the contributions of the vacuum condensates up to dimension-six,its first ten non-zero ξ-moments at the initial scale μ_(0)=1.3GeV are <ξ_(2;D_(s)^(*))^(‖,1)>}μ_(0)=-0.302_(-0.046)^(+0.038),<ξ_(2;D_(s)^(*))^(‖,2)>}μ_(0)=+0.229_(-0.034)^(+0.039),<ξ_(2;D_(s)^(*))^(‖,3)>}μ_(0)=-0.121_(-0.019)^(+0.015),<ξ_(2;D_(s)^(*))^(‖,4)>}μ_(0)=+0.101_(-0.014)^(+0.017),<ξ_(2;D_(s)^(*))^(‖,5)>}μ_(0)=-0.066_(-0.010)^(+0.009),<ξ_(2;D_(s)^(*))^(‖,6)>}μ_(0)=+0.053_(-0.007)^(+0.009),<ξ_(2;D_(s)^(*))^(‖,7)>}μ_(0)=-0.041_(-0.007)^(+0.006),<ξ_(2;D_(s)^(*))^(‖,8)>}μ_(0)=+0.037_(-0.005)^(+0.006),<ξ_(2;D_(s)^(*))^(‖,9)>}μ_(0)=-0.026_(-0.004)^(+0.003),and <ξ_(2;D_(s)^(*))^(‖,10)>}μ_(0)=+0.025_(-0.004)^(+0.004).We also construct the D_(s)^(*)-meson longitudinal leading-twist LCDA by using the light-cone harmonic oscillator model.Then,using the above moments,we fix the model parameters α_(2);D_(s)^(*) and B_(1)^(2;D_(s)^(*)) using the least squares method and apply them to calculate B_(s)→D_(s)^(*) transition form factors A_(1)(q^(2)),A_(2)(q^(2)) and V(q^(2)) that are derived using the QCD light-cone sum rules.In the large recoil region,we obtain A_(1)(0)=0.632_(-0.135)^(+0.228),A_(2)(0)=0.706_(-0.092)^(+0.109),,and V(0)=0.647_(-0.069)^(+0.076).These form factors are then extrapolated to the allowed whole physical q^(2)-region through the simplified series expansion.Finally,we obtain the branching fractions for the two decay channels of B_(s)→D_(s)^(*)lve,B(B_(s)^(0)→D_(s)^(*)e^(-)v_(e))=(5.45_(-1.57)^(+2.15))×10^(-2) and B(B_(s)^(0)→D_(s)^(*)μ^(-)v_(μ))=(5.43_(-1.57)^(+2.14))×10^(-2).In addition,we present the CKM matrix element |V_(cb)| by matching the LHCb Collaboration branching fraction,yielding a value of |V_(cb)|=(40.11+_(7.49)^(+6.54))×10^(-3).展开更多
The exclusive photoproduction of vector mesons(J/ψ/andφ)is investigated by considering the next-toleading order corrections in the framework of the color glass condensate.We compare the next-to-leading order modifie...The exclusive photoproduction of vector mesons(J/ψ/andφ)is investigated by considering the next-toleading order corrections in the framework of the color glass condensate.We compare the next-to-leading order modified dipole amplitude with the HERA data,finding a good agreement.Our studies show that theχ~2/d.o.f from the leading order,running coupling,and collinearly improved next-to-leading order dipole amplitudes are 2.159,1.097,and 0.932 for the elastic cross-section,and 2.056,1.449,and 1.357 for the differential cross-section,respectively.The results indicate that the higher-order corrections contribute significantly to the vector meson productions,and the description of the experimental data is dramatically improved once the higher order corrections are included.We extend the next-to-leading order exclusive vector meson production model to LHC energies using the same parameters obtained from HERA.We find that our model provides a rather good description of the J/ψandΦdata in proton-proton collisions at 7 TeV and 13 TeV in LHCb experiments.展开更多
Spin alignments of vector mesons and hyperons in relativistic heavy-ion collisions have been proposed as signals of global polarization.The STAR experiment first observed the ∧ polarization.Recently,the ALICE collabo...Spin alignments of vector mesons and hyperons in relativistic heavy-ion collisions have been proposed as signals of global polarization.The STAR experiment first observed the ∧ polarization.Recently,the ALICE collaboration measured the transverse momentum {PT) and the collision centrality dependence of K*,and Φ spin alignments during Pb-Pb collisions at 1/2sNN=2.76 TeV.A large signal is observed in the low pT region of mid-central collisions for K*,while the signal is much smaller for Φ,and these have not been understood yet.Since vector mesons have different lifetimes and their decay products have different scattering cross sections,they suffer from different hadronic effects.In this paper,we study the effect of hadronic interactions on the spin alignment of K*,Φ,and p mesons in relativistic heavy-ion collisions with a multi-phase transport model.We find that hadronic scatterings lead to a deviation of the observed spin alignment matrix element p00 away from the true value for p and K*mesons(with a bigger effect on p) while the effect is negligible for the Φ meson.The effect depends on the kinematic acceptance:the observed p00 value is lower than the true value when the pseudorapidity(η) coverage is small,while there is little effect when the η coverage is large.Hence,this study provides valuable information to understand the vector meson spin alignment signals observed during the experiments.展开更多
We study the vector meson electro-production off the proton in a QCD inspired model. A calculation of the differential cross section is performed for the J/ψ, Ф meson off the proton. The theoretical results are cons...We study the vector meson electro-production off the proton in a QCD inspired model. A calculation of the differential cross section is performed for the J/ψ, Ф meson off the proton. The theoretical results are consistent with the experimental data, and remind us to consider the contribution from the tensor glueball and Odderon to the differential cross section. Since gluons interact among themselves via self-interaction, the gluons can form a glueball with quantum numbers I^G, J^PC = 0^＋, 2^＋＋ with a decay width Гt = 100 MeV and mass of mG = 2.23 GeV. The three gluons can form a three gluon color bound state with charge conjugation quantum number C = -1. This study is quite important to verify the validity of QCD and to search for new particles （tensor glueball and Odderon） as well as quest for new physics.展开更多
The roles of the lightest vector mesons ρ and ω in the multi-Skyrmion states are studied using the hidden local symmetry approach up to the next-to-leading order,including the homogeneous Wess-Zumino terms.The low-e...The roles of the lightest vector mesons ρ and ω in the multi-Skyrmion states are studied using the hidden local symmetry approach up to the next-to-leading order,including the homogeneous Wess-Zumino terms.The low-energy constants in the effective field theory are determined using the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills action.With only two inputs,m_(ρ) and f_(π),it is possible to determine all low-energy constants without ambiguity.The vector meson effects can be investigated by sequentially integrating vector mesons,and their geometry can be elucidated by comparing the results using the low-energy constants estimated from the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills action.We found that theρmeson reduces the masses of the multi-Skyrmion states and increases the overlaps of their constituents,whereas theωmeson repulses the constituents of the multi-Skyrmion states and increases their masses.Therefore,these vector mesons are crucial in the Skyrme model approach to nuclei.We also found that the warping factor,an essential element in the holographic model of QCD,affects the properties of the multi-Skyrmion states and cannot be ignored.展开更多
基金supported by the National Key R&D Program of China(Grant No.2024YFA1611004)the National Natural Science Foundation of China(Grant Nos.12175117,12475084,and 12321005)the Shandong Province Natural Science Foundation(Grant Nos.ZFJH202303 and ZR2024MA012)。
文摘The transverse single-spin asymmetry forρ^(0) production in semi-inclusive deep inelastic scattering was recently reported by the COMPASS Collaboration.Using the Sivers function extracted from pion and kaon productions,we perform a calculation of the Sivers asymmetry within the transverse momentum-dependent factorization.Our results are consistent with the COMPASS data,supporting the universality of the Sivers function in the semi-inclusive deep inelastic scattering process for different final-state hadrons within current experimental uncertainties.While different parametrizations of the Sivers function from global analyses allow describing the data equally well,we obtain very different predictions on the Sivers asymmetry ofρand K^(*)productions at electron-ion colliders,which therefore are expected to provide further constraints.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11375021,11575017the New Century Excellent Talents in University(NCET)under Grant No.NCET-13-0030+1 种基金the Major State Basic Research Development Program of China under Grant No.2015CB856701the Fundamental Research Funds for the Central Universities
文摘Pure leptonic decays of D~*0)(B_^(*s),B_d~*)→l^+l^- and D^(±*)(D_s~*,B^(*+),B_c~*)→lν_l are investigated.The hadronic contributions such as D^0→D^(*0)γ→μ^+μ^- are also explored.We then obtain the updated branching fractions of the pseudoscalar mesons to lepton pairs are modified by a factor of few percentages.Specifically,the Br(B+→e^+ν_e)is reduced by a factor 13%.
基金the National Natural Science Foundation of China(NSFC)(12235016,12221005)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB34030000)+1 种基金the start-up funding from the University of Chinese Academy of Sciences(UCAS)the Fundamental Research Funds for the Central Universities。
文摘Vorticities in heavy-ion collisions(HICs)are supposed to induce spin alignment and polarization phenomena of quarks and mesons.In this work,we analyze the spin alignment of vector mesonsϕandρinduced by rotation from quark dynamics in the framework of the Nambu-Jona-Lasinio(NJL)model.The rotating angular velocity induces mass splitting of spin components for vectorϕ,ρmesons M_(ϕ,ρ)(Ω)≃M_(ϕ,ρ)(Ω=0)−szΩ.This behavior contributes to the spin alignment of vector mesonsϕ,ρin an equilibrium medium and naturally explains the negative deviation ofρ00−1/3 for vector mesons.Incidentally,the positive deviation ofρ00−1/3 under the magnetic field can also be easily understood from quark dynamics.
基金supported by the National Natural Science Foundation of China under Grant No.12165004 and and Key Grant No.12061141008the Basic and Applied Basic Research Project of Guangzhou Science and Technology Bureau under Grant No.202201011324+1 种基金the Education Department of Guizhou Province under Grant No.QJJ[2022]016the National Key Research and Development Program of China under Grant Nos.2024YFA1610800 and 2022YFA1602103。
文摘To investigate the possible geometric structure of the proton,an improved stringy proton model is constructed beyond the smallest distance approximation and treats the constituent(up and down)quark-initiated gluon tubes separately,where the constituent quarks are connected by gluon tubes which merge at the Fermat point of the quark triangle.The exclusive diffractive vector meson production process in electron-proton deep inelastic scattering is used to test the stringy structure of the proton.We calculate the coherent and incoherent differential cross sections of the exclusive diffractive J/Ψphotoproduction in the framework of Color Glass Condensate.The results show that our calculations are in good agreement with HERA data.Especially,our results give a better description of the HERA data at small t as compared to the ones from the hot spot model where the constituent quarks are independently distributed in the proton.Meanwhile,the radius of the proton resulting from the improved stringy proton model is coincident with the one from fitting to the data from GlueX Collaboration at Jefferson Lab,which indicates that the predictive power of the stringy proton model is significantly improved once it goes beyond the smallest distance approximation and treats the constituent quarks separately,instead of using the same profile for the up and down quarks initiated gluon tubes.Moreover,we assume that the transverse shape of the gluon tube satisfies Gaussian distribution,and explore the distribution width of the individual gluon tubes.We find an interesting result that the up quark-initiated gluon tube seems to have a larger distribution width than the down quarkinitiated gluon tube,which is favored by the HERA data.
文摘Based on Pomeron exchange model, elastic production of vector meson in electro-proton interaction is investigated with both linear and non-linear Pomeron trajectory. A numerical calculation for J/psi production is performed. The effect of the energy scale so and photon virtuality Q(2) on differential cross section are also predicted. A good agreement with experimental data is obtained. Our conclusions are that the Pomeron exchange model is a successful description of J/psi electro-production, the dependence of the differential cross sections on Q2 is negligible, the linear trajectory is a good approximation to non-linearity of the Pomeron trajectory, and the value of the energy scale parameter so is dependent on the momentum transfer, namely its effect is moderate at low momentum transfer but it causes no difference at high momentum transfer vertical bar t vertical bar >= 1.25 GeV2.
基金Supported by National Natural Science Foundation of China under Grant Nos.10647002 and 10565001
文摘Based on the quark-gluon contents of nucleon and strongly believing that the force mediators,Pomeronand its counterpart in the conventional approach of Regge theory,for high energy diffractive process would be the tensorglueball and Odderon respectively,we discuss photo-production of vector meson φ off the deuteron at energy less than 3GeV in the QCD inspired model in which the quark gluon degrees of freedom and glueball,Odderon exchange are takeninto account.A calculation is performed for γ + D →φ + D,and the theoretical predictions of the differential crosssection dσ^(γD)) /dt,are presented and compared with available experimental data.Our QCD inspired model reproducesdata quite well in the whole range of the experimental measurements up to |t| ■0.4 GeV.Our results can be used toextract γn→φn data,which cannot be measured in experiment.
基金Supported by the National Science Foundation of China(NSFC)under Grant Nos.11335001,11105153,11405178supported in part by the DFG and the NSFC(No.11261130311)through funds provided to the Sino-Germen CRC 110"Symmetries and the Emergence of Structure in QCD"performed on Tian He-1A supercomputer of the National Supercomputer Center in Tianjin
文摘Vector meson mass values are studied at finite chemical potential and temperature in lattice QCD with lattice size of 24 × 122× 6 using two flavors of staggered quarks. The investigation focuses on the change of the vector meson mass in the critical region close to T c with two different types of chemical potentials switched on: the isoscalar chemical potential μS and its isovector counterpart μV. It is found that the vector meson mass increases in the QGP phase with both chemical potentials and decreases with μS in the confinement phase.
基金Supported by National Natural Science Foundation of China under Grant No. 11075053the Fundamental Research Funds for the Central Universities
文摘In this article,we study the vector meson transitions among the charmonium and bottomonium states with the heavy quark effective theory in a systematic way,and make predictions for the ratios among the vector meson decay widths of a special multiplet to another multiplet.The predictions can be confronted with the experimental data in the future.
基金Supported by the National Natural Science Foundation of China(11805064,11975118)State Key Laboratory of Nuclear Physics and Technology,Peking university(NPT2025KFY03)。
文摘In this paper,a formalism is presented for the helicity amplitude analysis of the decays Ψ(2S)→γ_(1)χ_(c)J,χ_(c)J→γ_(2)V(V=p^(0),φ,ω)(subscripts 1 and 2 are used to distinguish the two radiative photons),and the polarization expressions of the P-wave charmonia χ_(c)J and the vector mesons p^(0),φ,ω for experimental measurements at an electron-positron collider.In addition,we derive formulae for the angular distributions of χ_(c1,2)→γV to extract the degree of transverse polarization P_(T) of e^(+)e^(-)pairs with symmetric beam energy as well as the ratios of two helicity amplitudes x(in χ_(c1) decays)and x,y(in χ_(c2) decays),which represent the relative magnitudes of transverse to longitudinal polarization amplitude.The results are validated by Monte Carlo simulation.Finally,the statistical sensitivity of P_(T),x,and y are estimated based on the large Ψ(2S)data samples collected at current and proposed future e^(+)e^(-)colliderexperiments.
基金supported in part by the National Key Research and Development Program of China(Grant No.2022YFA1604900)the National Natural Science Foundation of China(Grant Nos.12025501,11890710,11890713,11890714,12147101,and 12135011)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(Grant No.XDB34030102)the Natural Science Foundation of Shandong Province。
文摘The global spin alignment of vector mesons has been observed by the STAR collaboration at the Relativistic Heavy Ion Collider(RHIC)at Brookhaven National Laboratory(BNL).It provides a unique opportunity to probe the correlation between the po-larized quark and antiquark in the strongly coupled quark-gluon plasma(sQGP)produced in relativistic heavy ion collisions,opening a new window to explore the properties of sQGP.In addition,spin alignments of vector mesons have also been observed in other high-energy particle collisions such as e^(+)e^(−)annihilations at high energies where hadron production is dominated by quark fragmentation mechanism.The results obtained are quite different from those obtained in heavy ion collisions where quark coalescence/combination mechanism dominates suggesting strong dependence on hadronization mechanisms.So comprehensive studies in different hadronization processes are needed.In this article,we present a brief review of theoretical and experimen-tal advances in the study of vector meson’s spin alignments in a variety of high-energy particle collisions,with emphasis on hadronization mechanisms.
基金Supported in part by the Fundamental Research Funds for the Central Universities under Grant No.06500077the Spanish Ministerio de Economía y Competitividad and the European Regional Development Fund,under Grant Nos.FIS2014-51948-C2-1-P,FIS2014-51948-C2-2-P,SEV-2014-0398Generalitat Valenciana under Grant No.PROMETEOII/2014/0068
文摘The strong and electromagnetic corrections toρ-ωmixing are calculated using an SU(2)version of resonance chiral theory up to next-to-leading orders in 1/N_(C)expansion,respectively.Up to our accuracy,the effect of the momentum dependence ofρ-ωmixing is incorporated due to the inclusion of loop contributions.We analyze the impact ofρ-ωmixing on the pion vector form factor by performing numerical fit to the data extracted from e^(+)e^(-)→π^(+)π^(-)andτ→ν_(τ)2π,while the decay width ofω→π^(+)π^(-)is taken into account as a constraint.It is found that the momentum dependence is significant in a good description of the experimental data.In addition,based on the fitted values of the involved parameters,we analyze the decay width ofω→π^(+)π^(-),which turns out to be highly dominated by theρ-ωmixing effect.
基金The project supported in part by National Natural Science Foundation of China under Grant Nos. 10565001, 10647002 and the Natural Science Foundation of Guangxi under Grant No. 0481030, 0542042, and 0575020, Guangxi University under Grant No. X051001, and Guangxi University of Technology under Grant No. 05006
文摘Based on Pomeron exchange model, J/ψ and φ production in electro-proton interaction are investigated with both linear and non-linear Pomeron trajectory. The experimental differential cross sections measured as a function of the kinematic variable Q^2,W and t are reproduced successfully in the model. Our conclusions are that the Pomeron exchange model is a successful description of J/ψ and φ electro-productions on the proton, and that the linear trajectory is a good approximation to non-linearity of the Pomeron trajectory.
基金Supported by National Natural Science Foundation of China under Grant Nos.10647002,10565001the Guangxi Natural Science Foundation under Grant Nos.0575020,0542042,and 0481030
文摘Based on the generalized vector meson dominance model in QCD, we study photoproduction of vector meson T off the proton by use of the QCD inspired model in which the contributions from quark-quark, gluon-gluon, and quark-gluon interference term to observable are taken into consideration. Calculations are performed for total cross section σtot, differential cross section dσ/dt, ratio of the real part to imaginary part of forward scattering amplitude ρ, and nuclear slop parameter function β. The mediators of interactions between projectiles （the quark and antiquark pair fluctuated from the real the photon） and the proton target （three-quark system） are the tensor Glueball and Odderon instead of using the usual Pomeron exchange. The theoretical predictions for σtot （s） are consistent with the experimental data within error bars of the data. The data for dσ/dt, ρ, and β are urgently needed.
基金partially supported by CNPq—Conselho Nacional de Desenvolvimento Científico e Tecnologicoby FAPERJ—Fundacao Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiroby Coordenacao de Aperfeicoamento de Pessoal de Nível Superior—Brasil(CAPES),Finance Code 001。
文摘Holographic models that consider classical vector fields in a 5-d background provide effective descriptions for heavy vector meson spectra.This is true both in vacuum and a thermal medium,such as quark gluon plasma.However,the manner in which these phenomenological models work is unclear.In particular,what is the role of the fifth dimension,and what is the relation between the holographic 5-d background and physical(4-d)heavy mesons?Hadrons,in contrast to leptons,are composite particles with some internal structure that depends on the energy at which they are observed.In this study,a static meson is represented by a heavy quark-antiquark pair with an interaction described by a Nambu Goto string existing in the same 5-d background that provides field solutions leading to masses and decay constants of charmonium states.The resulting interaction potential is linear for large distances,with a string tension consistent with the effective Cornell potential.Introducing temperature T in the background,it is found for the J/ψcase that there is a deconfining transition at some critical value of T.The obtained results indicate that the 5-d background effectively represents the internal structure of the(static)charmonium(quasi)states.
基金Supported by German Science Foundation (DFG) in the frame ot the SFB/TR-16
文摘Measurements of ω photoproduction of the Crystal-Barrel/TAPS experiment at the ELSA accelerator of Bonn University are presented which used linearly polarized tagged photon beam from threshold to Eγ = 1700MeV. The azimuthal asymmetries ∑and ∑πindicate s-channel resonance contributions on top of the established t-channel exchange processes. These findings are further enhanced by a very first measurement of the G-asymmetry which, in addition to the polarized photon beam, also requires a longitudinally polarized proton target. An intuitive interpretation of the specific sensitivity of the azimuthal asymmetries to the reaction mechanisms involved is given.
基金Supported in part by the National Natural Science Foundation of China(12265009,12265010)the Project of Guizhou Provincial Department of Science and Technology(MS[2025]219,CXTD[2025]030,ZK[2023]024)。
文摘In this study,we continue an investigation of the semileptonic decays B_(s)→D_(s)^(*)lve.First,we derive the moments of the D_(s)^(*)-meson longitudinal leading-twist light-cone distribution amplitude (LCDA) based on QCD sum rules within the background field theory framework.Considering the contributions of the vacuum condensates up to dimension-six,its first ten non-zero ξ-moments at the initial scale μ_(0)=1.3GeV are <ξ_(2;D_(s)^(*))^(‖,1)>}μ_(0)=-0.302_(-0.046)^(+0.038),<ξ_(2;D_(s)^(*))^(‖,2)>}μ_(0)=+0.229_(-0.034)^(+0.039),<ξ_(2;D_(s)^(*))^(‖,3)>}μ_(0)=-0.121_(-0.019)^(+0.015),<ξ_(2;D_(s)^(*))^(‖,4)>}μ_(0)=+0.101_(-0.014)^(+0.017),<ξ_(2;D_(s)^(*))^(‖,5)>}μ_(0)=-0.066_(-0.010)^(+0.009),<ξ_(2;D_(s)^(*))^(‖,6)>}μ_(0)=+0.053_(-0.007)^(+0.009),<ξ_(2;D_(s)^(*))^(‖,7)>}μ_(0)=-0.041_(-0.007)^(+0.006),<ξ_(2;D_(s)^(*))^(‖,8)>}μ_(0)=+0.037_(-0.005)^(+0.006),<ξ_(2;D_(s)^(*))^(‖,9)>}μ_(0)=-0.026_(-0.004)^(+0.003),and <ξ_(2;D_(s)^(*))^(‖,10)>}μ_(0)=+0.025_(-0.004)^(+0.004).We also construct the D_(s)^(*)-meson longitudinal leading-twist LCDA by using the light-cone harmonic oscillator model.Then,using the above moments,we fix the model parameters α_(2);D_(s)^(*) and B_(1)^(2;D_(s)^(*)) using the least squares method and apply them to calculate B_(s)→D_(s)^(*) transition form factors A_(1)(q^(2)),A_(2)(q^(2)) and V(q^(2)) that are derived using the QCD light-cone sum rules.In the large recoil region,we obtain A_(1)(0)=0.632_(-0.135)^(+0.228),A_(2)(0)=0.706_(-0.092)^(+0.109),,and V(0)=0.647_(-0.069)^(+0.076).These form factors are then extrapolated to the allowed whole physical q^(2)-region through the simplified series expansion.Finally,we obtain the branching fractions for the two decay channels of B_(s)→D_(s)^(*)lve,B(B_(s)^(0)→D_(s)^(*)e^(-)v_(e))=(5.45_(-1.57)^(+2.15))×10^(-2) and B(B_(s)^(0)→D_(s)^(*)μ^(-)v_(μ))=(5.43_(-1.57)^(+2.14))×10^(-2).In addition,we present the CKM matrix element |V_(cb)| by matching the LHCb Collaboration branching fraction,yielding a value of |V_(cb)|=(40.11+_(7.49)^(+6.54))×10^(-3).
基金Supported by the National Natural Science Foundation of China(11765005,11947119,11305040,11847152,11775097)the Fund of Science and Technology Department of Guizhou Province([2018]1023,[2019]5653)+3 种基金the Education Department of Guizhou Province(KY[2017]004)Qian Kehe Platform Talents([2017]5736-027)the National key research and development program of China(2018YFE0104700,CCNU18ZDPY04)the 2018 scientific research startup foundation for the introduced talent of Guizhou University of Finance and Economics(2018YJ60)。
文摘The exclusive photoproduction of vector mesons(J/ψ/andφ)is investigated by considering the next-toleading order corrections in the framework of the color glass condensate.We compare the next-to-leading order modified dipole amplitude with the HERA data,finding a good agreement.Our studies show that theχ~2/d.o.f from the leading order,running coupling,and collinearly improved next-to-leading order dipole amplitudes are 2.159,1.097,and 0.932 for the elastic cross-section,and 2.056,1.449,and 1.357 for the differential cross-section,respectively.The results indicate that the higher-order corrections contribute significantly to the vector meson productions,and the description of the experimental data is dramatically improved once the higher order corrections are included.We extend the next-to-leading order exclusive vector meson production model to LHC energies using the same parameters obtained from HERA.We find that our model provides a rather good description of the J/ψandΦdata in proton-proton collisions at 7 TeV and 13 TeV in LHCb experiments.
基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34030000)the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030008)the National Natural Science Foundation of China(12025501,11890710,11890714,11775288)。
文摘Spin alignments of vector mesons and hyperons in relativistic heavy-ion collisions have been proposed as signals of global polarization.The STAR experiment first observed the ∧ polarization.Recently,the ALICE collaboration measured the transverse momentum {PT) and the collision centrality dependence of K*,and Φ spin alignments during Pb-Pb collisions at 1/2sNN=2.76 TeV.A large signal is observed in the low pT region of mid-central collisions for K*,while the signal is much smaller for Φ,and these have not been understood yet.Since vector mesons have different lifetimes and their decay products have different scattering cross sections,they suffer from different hadronic effects.In this paper,we study the effect of hadronic interactions on the spin alignment of K*,Φ,and p mesons in relativistic heavy-ion collisions with a multi-phase transport model.We find that hadronic scatterings lead to a deviation of the observed spin alignment matrix element p00 away from the true value for p and K*mesons(with a bigger effect on p) while the effect is negligible for the Φ meson.The effect depends on the kinematic acceptance:the observed p00 value is lower than the true value when the pseudorapidity(η) coverage is small,while there is little effect when the η coverage is large.Hence,this study provides valuable information to understand the vector meson spin alignment signals observed during the experiments.
基金Supported by National Natural Science Foundation of China (10647002)Guangxi Science Foundation for Young Researchers(0991009)+1 种基金Department of Guangxi Education (200807MS112)Natural Science Foundation of Guangxi University of Technology(0840211)
文摘We study the vector meson electro-production off the proton in a QCD inspired model. A calculation of the differential cross section is performed for the J/ψ, Ф meson off the proton. The theoretical results are consistent with the experimental data, and remind us to consider the contribution from the tensor glueball and Odderon to the differential cross section. Since gluons interact among themselves via self-interaction, the gluons can form a glueball with quantum numbers I^G, J^PC = 0^＋, 2^＋＋ with a decay width Гt = 100 MeV and mass of mG = 2.23 GeV. The three gluons can form a three gluon color bound state with charge conjugation quantum number C = -1. This study is quite important to verify the validity of QCD and to search for new particles （tensor glueball and Odderon） as well as quest for new physics.
基金supported by the National Natural Science Foundation of China(Grant Nos.11875147,and 12147103)。
文摘The roles of the lightest vector mesons ρ and ω in the multi-Skyrmion states are studied using the hidden local symmetry approach up to the next-to-leading order,including the homogeneous Wess-Zumino terms.The low-energy constants in the effective field theory are determined using the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills action.With only two inputs,m_(ρ) and f_(π),it is possible to determine all low-energy constants without ambiguity.The vector meson effects can be investigated by sequentially integrating vector mesons,and their geometry can be elucidated by comparing the results using the low-energy constants estimated from the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills action.We found that theρmeson reduces the masses of the multi-Skyrmion states and increases the overlaps of their constituents,whereas theωmeson repulses the constituents of the multi-Skyrmion states and increases their masses.Therefore,these vector mesons are crucial in the Skyrme model approach to nuclei.We also found that the warping factor,an essential element in the holographic model of QCD,affects the properties of the multi-Skyrmion states and cannot be ignored.
