arXiv subjects

Yan-Qing Zhao

Publications and source records attributed to Yan-Qing Zhao.

13 recordsLinked to original sources

arXiv2026

Holographic spectral functions of exotic spin-1 mesons

We develop a general holographic framework for computing thermal spectral functions of exotic spin--1 mesons. A bulk Proca mass encodes the canonical ultraviolet dimension of the interpolating operator, allowing channels with different ultraviolet scaling to be treated within a unified membrane-flow formalism in the zero-spatial-momentum limit. We test this framework in a soft-wall model with a gluon-condensate background for the hybrid $\pi_1$ and tetraquark-like $Z_c$ channels. The results show that dissociation temperatures of both channels lie below the phase transition temperatures. Increasing $c$ delays dissociation in both channels, but through different effects: both the vacuum-mass shift and thermal spectral deformation contribute in the $\pi_1$ channel, whereas the latter dominates in the $Z_c$ channel. Nevertheless, for the same environment, the $Z_c$ resonance dissociates at a lower temperature than the $\pi_1$ resonance.

hep-ph↗

arXiv2026

Holographic light-quark energy loss in a spinning plasma

In this work, we investigate light-quark energy loss in a strongly coupled plasma described by a spinning black-brane background obtained from the large-black-hole limit of the Myers--Perry geometry. The parameter $a$ characterizes the boost/rotation of the dual fluid in this holographic setup and is related to the angular velocity in the corresponding limit. We employ two complementary probes, the falling-string and shooting-string descriptions, to compute the stopping distance and the instantaneous energy loss of a light quark moving either transverse or parallel to the rotation axis. The results show that light quarks thermalize more readily in a hot environment. For parallel propagation, a counter-propagating configuration facilitates thermalization, whereas a co-propagating configuration suppresses it. For transverse propagation, increasing the magnitude of the rotational motion promotes thermalization. In addition, the instantaneous energy loss increases along the trajectory of the endpoint.

hep-ph↗

arXiv2026

Chaos in the near-horizon dynamics of the dyonic $\rm{AdS_4}$-Reissner-Nordstr\"{o}m black hole

We investigate the chaos in the dynamics of a probe massless particle confined by the harmonic potential near the horizon of the dyonic $\rm{AdS_4}$-Reissner-Nordstr\"om black hole. The total energy of the particle, chemical potential and magnetic field in this system serving as independently adjustable parameters tune nonlinearity and phase-space structure. By analyzing the trajectories on the Poincar\'e section and evaluating the Lyapunov exponents, we obtain the dynamical phase diagrams of the chaos and find their counteracting regulatory role: at low energy, chaos is enhanced and the Lyapunov exponent $\lambda_L$ violates its upper bound (i.e. surface gravity) in the extremal black hole limit(combined paramete $\Gamma=3$); at high energy, the same extremal limit suppresses chaos, with $\lambda_L$ dropping to zero and a regular dynamical corridor emerging along $\Gamma=3$ in the dynamical phase diagrams. These results establish a direct mapping between black hole thermodynamics and microscopic chaos, offering new insights into the AdS/QCD correspondence and nonlinear dynamics in strongly curved spacetimes.

hep-th↗

arXiv2024

Holographic spin alignment of $J/ψ$ meson in magnetized plasma

We study the mass spectra and spin alignment of vector meson $J/ψ$ in a thermal magnetized background using a generalized theoretical framework based on gauge/gravity duality. Utilizing a soft wall model for the QGP background and a massive vector field for the $J/ψ$ meson, we delve into the meson's spectral function and spin parameters $(λ_θ,\, λ_φ,\,λ_{θφ})$ for different cases, assessing their response to variations in magnetic field strength, momentum, and temperature. We initially examine scenarios where a meson's momentum aligns parallel to the magnetic field in helicity frame. Our results reveal a magnetic field-induced positive $λ_θ^\text{H}$ for low meson momentum, transitioning to negative with increased momentum. As a comparison, we also study the case of momentum perpendicular to the magnetic field and find the direction of magnetic field does not affect the qualitative behavior for the $eB$-dependence of $λ_θ^\text{H}$. Moreover, we apply our model to real heavy-ion collisions for three different spin quantization directions. Further comparisons with experimental data show qualitative agreement for spin parameters $λ_θ$ and $λ_φ$ in the helicity and Collins-Soper frames.

hep-ph↗

arXiv2024

Holographic spin alignment for vector mesons

We develop a general framework for studying the spin alignment $ρ_{00}$ for flavorless vector mesons by using the gauge/gravity duality. Focusing on the dilepton production through vector meson decay, we derive the relation between production rates at each spin channel and meson's spectral function, which can be evaluated by holographic models for a strongly coupled system. As examples, we study $ρ_{00}$ for $J/ψ$ and $ϕ$ mesons, induced by the relative motion to a thermal background, within the soft-wall model. We show that $ρ_{00}$ in the helicity frame for $J/ψ$ and $ϕ$ mesons have positive and negative deviations from 1/3 at $T=150$ MeV, respectively, which consequently leads to different properties for their global spin alignments.

hep-ph↗

arXiv2024

Configuration entropy of $Υ(1S)$ state in strong coupling plasma

To better understand the effects of strong coupling and QCD at high temperature in QGP, by using holographic model, we investigate the dissociation effect of bottomonium under the higher-order curvature corrections to the supergravity action corresponding to the corrections of large N expansion of boundary CFT in the side of field theory. The results show that effective potential is not a good physical quantity to estimate the dissociation strength of bottomonium in the case of finite wave number and considering the higher-order curvature corrections. Therefore, we calculate the quasinormal spectra(QNMs) and the differential configuration entropy(DCE). It is found that the dissociation effect is stronger for the stronger coupling.

hep-ph↗

arXiv2024

Phase structure and critical phenomena in 2-flavor QCD by holography

We explore the phase structure of Quantum Chromodynamics (QCD) with two dynamical quark flavors at finite temperature and baryon chemical potential, employing the non-perturbative gauge/gravity duality approach. Our gravitational model is tailored to align with state-of-the-art lattice data regarding the thermal properties of multi-flavor QCD. Following a rigorous parameter calibration to match equations of state and the QCD trace anomaly at zero chemical potential derived from cutting-edge lattice QCD simulations, we investigate thermodynamic quantities and order parameters. We predict the location of the critical endpoint (CEP) at $(μ_{\text{CEP}}, T_{\text{CEP}})=(219,182)$ MeV at which a line of first-order phase transitions terminate. We compute critical exponents associated with the CEP and find that they almost coincide with the critical exponents of the quantum 3D Ising model.

hep-ph↗

arXiv2023

$J/Ψ$ suppression in a rotating magnetized holographic QGP matter

We study the dissociation effect of $J/Ψ$ in magnetized, rotating QGP matter at finite temperature and chemical potential using gauge/gravity duality. By incorporating angular velocity into the holographic magnetic catalysis model, we analyze the influence of temperature, chemical potential, magnetic field, and angular velocity on the properties of $J/Ψ$ meson. The results reveal that temperature, chemical potential, and rotation enhance the dissociation effect and increase the effective mass in the QGP phase. However, the magnetic field suppresses dissociation, and its effect on the effective mass is non-trivial. Additionally, we explore the interplay between magnetic field and rotation, identifying a critical angular velocity that determines the dominant effect. As a parallel study, we also examine the rotation effect in the holographic inverse magnetic catalysis model, although the magnetic field exhibits distinctly different behaviors in these two models, the impact of rotation on the dissociation effect of $J/Ψ$ is similar. Finally, we investigate the influence of electric field and demonstrate that it also speeds up the $J/Ψ$ dissociation.

hep-ph↗

arXiv2023

Vector meson spectral function in a dynamical AdS/QCD model

By using gauge/gravity duality, we calculate the spectral function of the heavy vector mesons with the presence of an intense magnetic field in a hot and dense medium. The results show that, a general conclusion, as the increases of magnetic field, chemical potential and temperature, the height of the peak of the spectral function decreases and the width increases. A nontrivial result is the change from the peak position of spectral function. We explain this non-trivial behavior by the interplay of the interaction between the two heavy quarks and the interaction between the medium with each of the heavy quarks.

hep-ph↗

arXiv2023

Phase diagram of holographic thermal dense QCD matter with rotation

We study the rotation effects of the hot and dense QCD matter in a non-perturbative regime by the gauge/gravity duality. We use the gravitational model that is designated to match the state-of-the-art lattice data on the thermal properties of (2+1)-flavor QCD and predict the location of the critical endpoint and the first-order phase transition line at large baryon chemical potential without rotation. After introducing the angular velocity via a local Lorentz boost, we investigate the thermodynamic quantities for the system under rotation in a self-consistent way. We find that the critical temperature and baryon chemical potential associated with the QCD phase transition decrease as the angular velocity increases. Moreover, some interesting phenomena are observed near the critical endpoint. We then construct the 3-dimensional phase diagram of the QCD matter in terms of temperature, baryon chemical potential, and angular velocity. As a parallel investigation, we also consider the gravitational model of $SU(3)$ pure gluon system, for which the 2-dimensional phase diagram associated with temperature and angular velocity has been predicted. The corresponding thermodynamic quantities with rotation are investigated.

hep-ph↗

arXiv2020

Thermodynamics of heavy quarkonium in magnetic field background

We study the effect of magnetic field on heavy quark-antiquark pair in both Einstein-Maxwell(EM) and Einstein-Maxwell-Dilaton(EMD) model. The interquark distance, free energy, entropy, binding energy and internal energy of the heavy quarkonium are calculated. It is found that the free energy suppresses and the entropy increases quickly with the increase of the magnetic field $B$. The binding energy vanishes at smaller distance when increasing the magnetic field, which indicates the quark-antiquark pair dissociates at smaller distance. The internal energy which consists of free energy and entropy will increase at large separating distance for non-vanishing magnetic field. These conclusions are consistent both in the EM and EMD model. Moreover, we also find that the quarkonium will dissociate easier in the parallel direction than that in the transverse direction for EMD model, but the conclusion is opposite in EM model. Lattice results are in favor of EMD model. Besides, a Coulomb-plus-linear potential(Cornell potential) can be realized only in EMD model. Thus, a dilaton field is proved to be important in holographic model. Finally, we also show that the free energy, entropy and internal energy of a single quark in EMD model with the presence of magnetic field.

hep-ph↗

arXiv2020

The effect of gluon condensate on imaginary potential and thermal width from holography

By the use of the gauge/gravity duality, we calculate the imaginary part of heavy quarkonium potential and thermal width with the effect of gluon condensate which is absent in AdS$_{5}$ background. Our results show that the dropping gluon condensate reduces the absolute value of imaginary potential and therefore decreases the thermal width both in "exact" and "approximate" approach implying that the heavy quarkonium has a weaker bound with the increase of gluon condensate. In addition, the thermal width will disappear at a critical condensate value, which indicates the dissociation of quarkonium. We conclude that increasing gluon condensate will lead to easier dissociation of heavy quarkonium for fixed temperature.

hep-ph↗

arXiv2019

A systematically study of thermal width of heavy quarkonia in a finite temperature magnetized background from holography

By simulating the finite temperatures magnetized background in the RHIC and LHC energies, we systematically study the characteristics of thermal widths and potentials of heavy quarkonia. It is found that the magnetic field has less influence on the real potential, but has a significant influence on the imaginary potential, especially in the low deconfined temperature. Extracted from the effect of thermal worldsheet fluctuations about the classical configuration, the thermal width of $Υ(1s)$ in the finite temperature magnetized background is investigated. It is found that at the low deconfined temperature the magnetic field can generate a significant thermal fluctuation of the thermal width of $Υ(1s)$, but with the increase of temperature, the effect of magnetic field on the thermal width becomes less important, which means the effect of high temperature completely exceeds that of magnetic field and magnetic field become less important at high temperature. The thermal width decreases with the increasing rapidity at the finite temperature magnetized background. It is also observed that the effect of the magnetic field on the thermal width when dipole moving parallel to the magnetic field direction are larger than that moving perpendicular to the magnetic field direction, which implies that the magnetic field tends to enhance thermal fluctuation when dipole moving parallel to the direction of magnetic field. The thermal width of $Υ(1S)$ hardly changes with the increasing temperature when dipole moving perpendicular to the magnetic field. But when dipole moving parallel to the magnetic field, the thermal width at low temperature is obviously larger than that at high temperature.

hep-ph↗