Based on an IR-improved soft-wall AdS/QCD model for mesons, which provides a consistent prediction for the mass spectra of resonance scalar, pseudoscalar, vector and axial-vector mesons, we investigate its finite temp...Based on an IR-improved soft-wall AdS/QCD model for mesons, which provides a consistent prediction for the mass spectra of resonance scalar, pseudoscalar, vector and axial-vector mesons, we investigate its finite temperature effect. By analyzing the spectral function of mesons and fitting it with a Breit-Wigner form, we perform an analysis for the critical temperature of mesons. The back-reaction effects of bulk vacuum are considered and the thermal mass spectral function of resonance mesons is calculated based on the back-reaction improved action. A reasonable melting temperature is found to be Tc ≈150 ± 7 MeV, which is consistent with the recent results from lattice QCD simulations.展开更多
We study the phase transition between the pion condensed phase and normal phase,as well as chiral phase transition in a two flavor(Nf=2)IR-improved soft-wall AdS/QCD model at finite isospin chemical potentialμI and t...We study the phase transition between the pion condensed phase and normal phase,as well as chiral phase transition in a two flavor(Nf=2)IR-improved soft-wall AdS/QCD model at finite isospin chemical potentialμI and temperature T.By self-consistently solving the equations of motion,we obtain the phase diagram in the plane ofμI and T.The pion condensation appears together with a massless Nambu-Goldstone boson mπ1(Tc,μcI)=0,which is very likely to be a second-order phase transition with mean-field critical exponents in the smallμI region.When T=0,the critical isospin chemical potential approximates to vacuum pion massμcI≈m0.The pion condensed phase exists in an arched area,and the boundary of the chiral crossover intersects the pion condensed phase at a tri-critical point.Qualitatively,the results are in good agreement with previous studies on lattice simulations and model calculations.展开更多
We review a recent work on masses of mesons and nucleons within a hard wall model of holographic QCD in a unified approach.In order to treat meson and nucleon properties on the same footing,we introduced the same infr...We review a recent work on masses of mesons and nucleons within a hard wall model of holographic QCD in a unified approach.In order to treat meson and nucleon properties on the same footing,we introduced the same infrared （IR） cut for both sectors.In framework of present approach,the best fit to the experimental data is achieved introducing the anomalous dimension for baryons.展开更多
The scalar glueball is investigated in a soft-wall model of AdS/QCD. Constraints of the mass of the scalar glueball are given through an analysis of a relation between the bulk mass and the anomalous dimension. The ma...The scalar glueball is investigated in a soft-wall model of AdS/QCD. Constraints of the mass of the scalar glueball are given through an analysis of a relation between the bulk mass and the anomalous dimension. The mass of the ground scalar glueball is located at 0.96＋-0.07 ＋0.04 GeV 〈 MG 〈 1.36＋0.05 -0.10 GeV. In terms of a background dilaton field θ（z）= cz2, the two-point correlation function for the scalar gluon operator is obtained. The two-point correlation function at A=4 gives a different behavior compared with the one in QCD.展开更多
We construct an improved soft-wall AdS/QCD model with a cubic coupling term of the dilaton and the bulk scalar field.The background fields in this model are solved by the Einstein-dilaton system with a nontrivial dila...We construct an improved soft-wall AdS/QCD model with a cubic coupling term of the dilaton and the bulk scalar field.The background fields in this model are solved by the Einstein-dilaton system with a nontrivial dilaton potential,which has been shown to reproduce the equation of state from the lattice QCD with two flavors.The chiral transition behaviors are investigated in the improved soft-wall AdS/QCD model with the solved gravitational background,and the crossover transition can be realized.Our study provides the possibility to address the deconfining and chiral phase transitions simultaneously in the bottom-up holographic framework.展开更多
We study the effect of chemical potential and nonconformality on the jet quenching parameter in a holographic QCD model with conformal invariance broken by background dilaton.The presence of chemical potential and non...We study the effect of chemical potential and nonconformality on the jet quenching parameter in a holographic QCD model with conformal invariance broken by background dilaton.The presence of chemical potential and nonconformality both increase the jet quenching parameter,thus enhancing the energy loss,consistently with the findings of the drag force.展开更多
To study drag force on a moving heavy quark through a plasma,we use a deformed AdS spacetime,in which deformation parameter c describes non-conformality in AdS/QCD.In this case,the quark is mapped to a probe string in...To study drag force on a moving heavy quark through a plasma,we use a deformed AdS spacetime,in which deformation parameter c describes non-conformality in AdS/QCD.In this case,the quark is mapped to a probe string in the AdS space.Considering the probable contribution of the deformation parameter in the probe string,we apply a general form of c-dependent string ansatz in the drag force computation.Then,we find the acceptable value of this parameter as it satisfies QCD calculations.Using this result,we also discuss the diffusion constant which is in agreement with the phenomenological result for the non-relativistic limit.Also,we show that while in absence of a deformation parameter,the probe string is a strictly increasing function of radial coordinate,the c-dependent probe string has a maximum value versus z.展开更多
Because of the presence of modified warp factors in metric tensors,we use deformed AdS5 spaces to apply the AdS/CFT correspondence to calculate the spectra for even and odd glueballs,scalar and vector mesons,and baryo...Because of the presence of modified warp factors in metric tensors,we use deformed AdS5 spaces to apply the AdS/CFT correspondence to calculate the spectra for even and odd glueballs,scalar and vector mesons,and baryons with different spins.For the glueball cases,we derive their Regge trajectories and compare them with those related to the pomeron and the odderon.For the scalar and vector mesons,as well as baryons,the determined masses are compatible with the PDG.In particular,for these hadrons we found Regge trajectories compatible with another holographic approach as well as with the hadronic spectroscopy,which present an universal Regge slope of approximately 1.1 GeV^2.展开更多
We investigate the AdS/QCD duality for the two-point correlation functions of the lowest dimension scalar meson and scalar glueball operators,in the case of the Soft Wall holographic model of QCD.Masses and decay cons...We investigate the AdS/QCD duality for the two-point correlation functions of the lowest dimension scalar meson and scalar glueball operators,in the case of the Soft Wall holographic model of QCD.Masses and decay constants as well as gluon condensates are compared to their QCD estimates.In particular,the role of the boundary conditions for the bulk-to-boundary propagators is emphasized.展开更多
We studied the condensate mass of QCD vacuum through the duality approach via dilaton wall back-ground in the presence of the parameter c,which represents the condensation in a holographic set up.First,fromWilson line...We studied the condensate mass of QCD vacuum through the duality approach via dilaton wall back-ground in the presence of the parameter c,which represents the condensation in a holographic set up.First,fromWilson line calculation,we found m_(0)^(2)(i.e.,the condensate parameter in mixed non-local condensation),whose beha-vior mimics that of QCD.The value of m_(0)^(2)that we found by this approach is in agreement with QCD data.Second we considered the produced mass m via the Schwinger effect mechanism in the presence of the parameter c.We show that vacuum condensation generally contributes the mass dominantly and that the produced mass via Schwing.er effect is suppressed by m_(0).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
In this study,we discuss the description of neutral Σ baryons with I(J^(P))=1(1/2^(+))and I(J^(P))=1(3/2^(+))using two bottom-up approaches:the deformed background and static dilaton models.In both models,we consider...In this study,we discuss the description of neutral Σ baryons with I(J^(P))=1(1/2^(+))and I(J^(P))=1(3/2^(+))using two bottom-up approaches:the deformed background and static dilaton models.In both models,we consider a non-linear Regge trajectory extension motivated by the strange nature of Σ baryons.We find that both models describe these systems with an RMS error smaller than 10%.We also perform a configurational entropy calculation in both models to discuss hadronic stability.展开更多
The mass pattern of nucleon and Δ resonances is compared with predictions based on quark models,the Skyrme model,AdS/QCD,and the conjecture of chiral symmetry restoration.
We study the deep inelastic scattering(DIS)of a proton-targeted lepton in the presence of gluon condensation using gauge/gravity duality.We use a modified AdS5background where the modification parameter c corresponds ...We study the deep inelastic scattering(DIS)of a proton-targeted lepton in the presence of gluon condensation using gauge/gravity duality.We use a modified AdS5background where the modification parameter c corresponds to the gluon condensation in the boundary theory.First,by examining the electromagnetic field,we establish that a non-zero c can increase field magnitude.Our aim is to obtain the acceptable value of c for this scattering.Our method is based on setting the mass of the proton as an eigenvalue of the baryonic state equations of the DIS to find the acceptable value of the parameter c on the other side of the equations.Therefore,in the second step,we calculate wave function equations for the baryonic states where the mass of the proton target requires a value contribution of c as c=0.0120 GeV4.Proceeding with the electromagnetic field and baryonic states,we derive the holographic interaction action related to the amplitude of the scattering.Finally,we compute the corresponding structure functions numerically as functions of x and q,which are Bj?rken variables and the lepton momentum transfers,respectively.Comparing the Jlab Hall C data with our theoretical calculations,our results are acceptable.展开更多
Understanding the nature of quantum chromodynamics(QCD)matter is important but challenging due to the presence of nonperturbative dynamics under extreme conditions.We construct a holographic model describing the gluon...Understanding the nature of quantum chromodynamics(QCD)matter is important but challenging due to the presence of nonperturbative dynamics under extreme conditions.We construct a holographic model describing the gluon sector of QCD at finite temperatures in the non-perturbative regime.The equation of state as a function of temperature is in good accordance with the lattice QCD data.Moreover,the Polyakov loop and the gluon condensation,which are proper order parameters to capture the deconfinement phase transition,also agree quantitatively well with the lattice QCD data.We obtain a strong first-order confinement/deconfinement phase transition at Tc=276.5 Me V that is consistent with the lattice QCD prediction.Based on our model for a pure gluon hidden sector,we compute the stochastic gravitational waves and primordial black hole(PBH)productions from this confinement/deconfinement phase transition in the early Universe.The resulting stochastic gravitational-wave backgrounds are found to be within detectability in the International Pulsar Timing Array and Square Kilometre Array in the near future when the associated productions of PBHs saturate the current observational bounds on the PBH abundances from the LIGO-Virgo-Collaboration O3 data.展开更多
基金Supported by National Nature Science Foundation of China(NSFC)(10975170,10905084,10821504)Project of Knowledge Innovation Program(PKIP)of Chinese Academy of Science
文摘Based on an IR-improved soft-wall AdS/QCD model for mesons, which provides a consistent prediction for the mass spectra of resonance scalar, pseudoscalar, vector and axial-vector mesons, we investigate its finite temperature effect. By analyzing the spectral function of mesons and fitting it with a Breit-Wigner form, we perform an analysis for the critical temperature of mesons. The back-reaction effects of bulk vacuum are considered and the thermal mass spectral function of resonance mesons is calculated based on the back-reaction improved action. A reasonable melting temperature is found to be Tc ≈150 ± 7 MeV, which is consistent with the recent results from lattice QCD simulations.
基金Supported by the National Natural Science Foundation of China(11405074)Supported by the National Natural Science Foundation of China(11805084)+1 种基金the PhD Start-up Fund of Natural Science Foundation of Guangdong Province(2018030310457)Guangdong Pearl River Talents Plan(2017GC010480)。
文摘We study the phase transition between the pion condensed phase and normal phase,as well as chiral phase transition in a two flavor(Nf=2)IR-improved soft-wall AdS/QCD model at finite isospin chemical potentialμI and temperature T.By self-consistently solving the equations of motion,we obtain the phase diagram in the plane ofμI and T.The pion condensation appears together with a massless Nambu-Goldstone boson mπ1(Tc,μcI)=0,which is very likely to be a second-order phase transition with mean-field critical exponents in the smallμI region.When T=0,the critical isospin chemical potential approximates to vacuum pion massμcI≈m0.The pion condensed phase exists in an arched area,and the boundary of the chiral crossover intersects the pion condensed phase at a tri-critical point.Qualitatively,the results are in good agreement with previous studies on lattice simulations and model calculations.
基金Supported by AvH,Basic Science Research Program through National Research Foundation of Korea (NRF) funded by Ministry of Education,Science and Technology (2009-0073101)
文摘We review a recent work on masses of mesons and nucleons within a hard wall model of holographic QCD in a unified approach.In order to treat meson and nucleon properties on the same footing,we introduced the same infrared （IR） cut for both sectors.In framework of present approach,the best fit to the experimental data is achieved introducing the anomalous dimension for baryons.
基金Supported by National Natural Science Foundation of China(11075102)Innovation Program of Shanghai Municipal Education Commission(13ZZ066)
文摘The scalar glueball is investigated in a soft-wall model of AdS/QCD. Constraints of the mass of the scalar glueball are given through an analysis of a relation between the bulk mass and the anomalous dimension. The mass of the ground scalar glueball is located at 0.96＋-0.07 ＋0.04 GeV 〈 MG 〈 1.36＋0.05 -0.10 GeV. In terms of a background dilaton field θ（z）= cz2, the two-point correlation function for the scalar gluon operator is obtained. The two-point correlation function at A=4 gives a different behavior compared with the one in QCD.
基金Supported in part by the National Natural Science Foundation of China(NSFC)(11851302,11851303,11690022,11747601)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB23030100)as well as the CAS Center for Excellence in Particle Physics(CCEPP)+1 种基金Z.F.is also Supported by the NSFC(11905055)the Fundamental Research Funds for the Central Universities(531118010198)。
文摘We construct an improved soft-wall AdS/QCD model with a cubic coupling term of the dilaton and the bulk scalar field.The background fields in this model are solved by the Einstein-dilaton system with a nontrivial dilaton potential,which has been shown to reproduce the equation of state from the lattice QCD with two flavors.The chiral transition behaviors are investigated in the improved soft-wall AdS/QCD model with the solved gravitational background,and the crossover transition can be realized.Our study provides the possibility to address the deconfining and chiral phase transitions simultaneously in the bottom-up holographic framework.
基金Supported by Zhejiang Provincial Natural Science Foundation of China(LY19A050001,LY18A050002)the NSFC(11705166,11947410)。
文摘We study the effect of chemical potential and nonconformality on the jet quenching parameter in a holographic QCD model with conformal invariance broken by background dilaton.The presence of chemical potential and nonconformality both increase the jet quenching parameter,thus enhancing the energy loss,consistently with the findings of the drag force.
基金supported by Strategic Priority Research Program of Chinese Academy of Sciences(XDB34030301)supported by the PIFI(2021PM0065)。
文摘To study drag force on a moving heavy quark through a plasma,we use a deformed AdS spacetime,in which deformation parameter c describes non-conformality in AdS/QCD.In this case,the quark is mapped to a probe string in the AdS space.Considering the probable contribution of the deformation parameter in the probe string,we apply a general form of c-dependent string ansatz in the drag force computation.Then,we find the acceptable value of this parameter as it satisfies QCD calculations.Using this result,we also discuss the diffusion constant which is in agreement with the phenomenological result for the non-relativistic limit.Also,we show that while in absence of a deformation parameter,the probe string is a strictly increasing function of radial coordinate,the c-dependent probe string has a maximum value versus z.
基金H.B-F.would like to thank partial financial support from Conselho Nacional de Desenvolvimento Cientifíco e Tecnológico(CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior(Capes)(Brazilian Agencies).A.V.+3 种基金M.A.M.C.would like to thank the financial support given by FONDECYT(Chile)(1180753,3180592)respectivelyD.L.is supported by the National Natural Science Foundation of China(11805084)the PhD Start-up Fund of Natural Science Foundation of Guangdong Province(2018030310457)Guangdong Pearl River Talents Plan(2017GC010480)。
文摘Because of the presence of modified warp factors in metric tensors,we use deformed AdS5 spaces to apply the AdS/CFT correspondence to calculate the spectra for even and odd glueballs,scalar and vector mesons,and baryons with different spins.For the glueball cases,we derive their Regge trajectories and compare them with those related to the pomeron and the odderon.For the scalar and vector mesons,as well as baryons,the determined masses are compatible with the PDG.In particular,for these hadrons we found Regge trajectories compatible with another holographic approach as well as with the hadronic spectroscopy,which present an universal Regge slope of approximately 1.1 GeV^2.
基金Invited talk at the 5 th International Conference on Quarks and Nuclear Physics QNP 2009,Beijing,China,21-26 September 2009
文摘We investigate the AdS/QCD duality for the two-point correlation functions of the lowest dimension scalar meson and scalar glueball operators,in the case of the Soft Wall holographic model of QCD.Masses and decay constants as well as gluon condensates are compared to their QCD estimates.In particular,the role of the boundary conditions for the bulk-to-boundary propagators is emphasized.
基金National Natural Science Foundation of China(11575254)the National Key Research and Development Program of China(2016YFE0130800)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34030301)ST is supported by the PIFI(2021PM0065)。
文摘We studied the condensate mass of QCD vacuum through the duality approach via dilaton wall back-ground in the presence of the parameter c,which represents the condensation in a holographic set up.First,fromWilson line calculation,we found m_(0)^(2)(i.e.,the condensate parameter in mixed non-local condensation),whose beha-vior mimics that of QCD.The value of m_(0)^(2)that we found by this approach is in agreement with QCD data.Second we considered the produced mass m via the Schwinger effect mechanism in the presence of the parameter c.We show that vacuum condensation generally contributes the mass dominantly and that the produced mass via Schwing.er effect is suppressed by m_(0).
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 the National Natural Science Foundation of China(12350410371)supported by the Research Foundation of Education Bureau of Hunan Province,China(21B0402)the Natural Science Foundation of Hunan Province,China(2022JJ40344)。
文摘In this study,we discuss the description of neutral Σ baryons with I(J^(P))=1(1/2^(+))and I(J^(P))=1(3/2^(+))using two bottom-up approaches:the deformed background and static dilaton models.In both models,we consider a non-linear Regge trajectory extension motivated by the strange nature of Σ baryons.We find that both models describe these systems with an RMS error smaller than 10%.We also perform a configurational entropy calculation in both models to discuss hadronic stability.
基金Supported within SFB/TR16 by the Deutsche Forschungsgemeinschaft
文摘The mass pattern of nucleon and Δ resonances is compared with predictions based on quark models,the Skyrme model,AdS/QCD,and the conjecture of chiral symmetry restoration.
基金Supported by Strategic Priority Research Program of Chinese Academy of Sciences(XDB34030301)ST is supported by the PIFI(2021PM0065)。
文摘We study the deep inelastic scattering(DIS)of a proton-targeted lepton in the presence of gluon condensation using gauge/gravity duality.We use a modified AdS5background where the modification parameter c corresponds to the gluon condensation in the boundary theory.First,by examining the electromagnetic field,we establish that a non-zero c can increase field magnitude.Our aim is to obtain the acceptable value of c for this scattering.Our method is based on setting the mass of the proton as an eigenvalue of the baryonic state equations of the DIS to find the acceptable value of the parameter c on the other side of the equations.Therefore,in the second step,we calculate wave function equations for the baryonic states where the mass of the proton target requires a value contribution of c as c=0.0120 GeV4.Proceeding with the electromagnetic field and baryonic states,we derive the holographic interaction action related to the amplitude of the scattering.Finally,we compute the corresponding structure functions numerically as functions of x and q,which are Bj?rken variables and the lepton momentum transfers,respectively.Comparing the Jlab Hall C data with our theoretical calculations,our results are acceptable.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFC2203004,and 2020YFC2201501)the National Natural Science Foundation of China(Grant Nos.12075101,12235016,12122513,12075298,12047569,11991052,12047503,12105344,11947233,and 12235019)+3 种基金the Key Research Program of the Chinese Academy of Sciences(CAS)(Grant No.XDPB15)the Science Research Grants from the China Manned Space Project(Grant No.CMS-CSST-2021-B01)the financial support from Jilin UniversityMax Planck Partner group。
文摘Understanding the nature of quantum chromodynamics(QCD)matter is important but challenging due to the presence of nonperturbative dynamics under extreme conditions.We construct a holographic model describing the gluon sector of QCD at finite temperatures in the non-perturbative regime.The equation of state as a function of temperature is in good accordance with the lattice QCD data.Moreover,the Polyakov loop and the gluon condensation,which are proper order parameters to capture the deconfinement phase transition,also agree quantitatively well with the lattice QCD data.We obtain a strong first-order confinement/deconfinement phase transition at Tc=276.5 Me V that is consistent with the lattice QCD prediction.Based on our model for a pure gluon hidden sector,we compute the stochastic gravitational waves and primordial black hole(PBH)productions from this confinement/deconfinement phase transition in the early Universe.The resulting stochastic gravitational-wave backgrounds are found to be within detectability in the International Pulsar Timing Array and Square Kilometre Array in the near future when the associated productions of PBHs saturate the current observational bounds on the PBH abundances from the LIGO-Virgo-Collaboration O3 data.
