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1.
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.  相似文献   

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Holographic quantum chromodynamics (QCD) is an extra-dimensional approach to modelling hadrons, the bound states of the strong interactions. In holographic models, the extra spatial dimension creates a waveguide for fields, and the discrete towers of modes propagating in that waveguide are interpreted as hadronic resonances. These models are motivated by the AdS/CFT correspondence, which is a duality that relates theories in different numbers of spatial dimensions. Holographic models have the potential to provide a better understanding of strongly interacting systems of quarks and gluons, as well as unconventional superconductors and other nonperturbative systems.  相似文献   

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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.  相似文献   

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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.  相似文献   

6.
We perform a holographic renormalization of the supergravity action and compute the stress tensor of the dual gauge theory incorporating the logarithmic running of the gauge coupling. From the stress tensor we obtain the shear viscosity and the entropy of the medium at temperature T, and investigate the ratio η/s.  相似文献   

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We give a brief introduction to the AdS/CFT correspondence and its application to QCD physics, especially its application in the study of quark-gluon-plasma(QGP) formed in the relativistic heavy ion collision (RHIC). This review is based on the talksgiven in several schools and programs for the phenomenologists working on nuclear physicsand particle physics.  相似文献   

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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)GeVmGl.36_(-0.10)~(+0.05)GeV.In terms of a background dilaton fieldΦ(z)=cz~2,the two-point correlation function for the scalar gluon operator is obtained.The two-point correlation function at△=4 gives a different behavior compared with the one in QCD.  相似文献   

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To study drag force on a moving heavy quark through a plasma, we use a deformed AdS space-time, 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.  相似文献   

10.
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In this study, we utilize the complexity-action duality to study the evolution of complexity in a holographic QCD model at finite temperature and chemical potential. By inserting a fundamental string as a probe, we investigated the properties of complexity growth in this Einstein-Maxwell-scalar gravity system, which is affected by the string velocity, chemical potential, and temperature. Our results show that the complexity growth is maximized when the probe string is stationary, and it decreases as the velocity of the string increases. When the string approaches relativistic velocities, the complexity growth always increases monotonically with respect to the chemical potential. Furthermore, we find that the complexity growth can be used to identify phase transitions and crossovers in the model.  相似文献   

11.
We discuss how a dominant tetraquark component of the lightest scalar mesons may emerge in AdS/QCD gravity duals. In particular, we show that the exceptionally strong binding required to render the tetraquark ground state lighter than the lowest-lying scalar quark–antiquark nonet can be holographically encoded into bulk-mass corrections for the tetraquark's dual mode. The latter are argued to originate from the anomalous dimension of the corresponding four-quark interpolator. To provide a concrete example, we implement this mechanism into the dilaton soft-wall dual for holographic QCD. Preventing the lowest-lying dual mode from collapsing into the AdS boundary then establishes a rather generic lower bound on the tetraquark mass (which may be overcome in the presence of additional background fields). We further demonstrate that the higher tetraquark excitations can become heavier than their quark–antiquark counterparts and are thus likely to dissolve into the multiparticle continuum.  相似文献   

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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 begin{document}${rm AdS}_5$end{document} background 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 begin{document}$ c=0.0120 ; rm GeV^4 $end{document}. 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.  相似文献   

13.
Decays of both η and η' provide very useful information in our understanding of low-energy QCD,and experimental signatures for these decays would be extremely helpful at BES-Ⅲ.The rare decays of the η and η' mesons could serve as a low-energy test of the Standard Model and its beyond.The sensitivities of the measurements of η and η' decays are discussed at BES-Ⅲ,in which the η and η' mesons are produced in the ψ decays.  相似文献   

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Zhen Fang  Yue-Liang Wu 《中国物理C(英文版)》2020,44(10):103101-103101-10
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.  相似文献   

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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.  相似文献   

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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.  相似文献   

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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.  相似文献   

20.
Decays of both η and η' provide very useful information in our understanding of low-energy QCD, and experimental signatures for these decays would be extremely helpful at BES-III. The rare decays of the η and η' mesons could serve as a low-energy test of the Standard Model and its beyond. The sensitivities of the measurements of η and η' decays are discussed at BES-III, in which the η and η' mesons are produced in the ψ decays.  相似文献   

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