arXiv subjects

Guoyun Shao

Publications and source records attributed to Guoyun Shao.

6 recordsLinked to original sources

arXiv2026

$q\bar{q}$ scattering phase shift in the $\pi^0$ channel and ${\pi}^0$ meson spectral function under external magnetic field and finite meson momentum

$q\bar{q}$ scattering phase shift in the $\pi^0$ channel $\Phi_{\pi^0}(\omega^2,\mathbf{k}_\perp^2,k^2_3)$ and ${\pi}^0$ meson spectral function $\rho_{\pi^0}(\omega^2,\mathbf{k}_\perp^2,k^2_3)$ under external magnetic field $eB$ and finite meson momentum $\mathbf{k}_\perp^2,k^2_3$ are studied in the framework of a two-flavor Nambu-Jona-Lasinio (NJL) model. The $q\bar{q}$ scattering phase shift in the $\pi^0$ channel $\Phi_{\pi^0}$ is closely related to $\pi^0$ spectral function $\rho_{\pi^0}$. We consider three situations, chiral broken phase ($T=\mu=0$), chiral restoration phase ($T>T_{pc},\ \mu=0$) and chiral restoration phase ($T=0,\ \mu>\mu_{pc}$). For $T=\mu=0$ and $T>T_{pc},\ \mu=0$ cases, ${\pi}^0$ meson spectral function $\rho_{\pi^0}$ shows a delta peak, several Breit-Wigner peaks and several non-Breit-Wigner peaks. The delta peak indicates the bound state of $\pi^0$ meson, and the Breit-Wigner peak means the resonant state of $\pi^0$ meson. For $T=0,\ \mu>\mu_{pc}$ case, Pauli blocking effect plays a role, which changes the inner structure of these Breit-Wigner peaks and non-Breit-Wigner peaks. Such multiple peak structure is caused by the external magnetic field. The $q\bar{q}$ scattering phase shift in the $\pi^0$ channel $\Phi_{\pi^0}$ shows a jump from $0$ to $\pi$ when $\pi^0$ meson is in bound state. When $\pi^0$ meson is in resonant state, $\Phi_{\pi^0}$ has the value $\pi/2$ and changes continuously. In large $\omega$ region, at the starting and end points of wide peaks of spectral function, $\Phi_{\pi^0}$ jumps abruptly (from $\pi$ to finite value or from finite value to $0$), and such jumps are caused by the external magnetic field. Finite momentum $\mathbf{k}_\perp^2$ or $k^2_3$ modifies the spectral function $\rho_{\pi^0}$ and scattering phase shift $\Phi_{\pi^0}$, which demonstrates the anisotropy in the system induced by external magnetic field.

hep-ph↗

arXiv2026

Fourth order correlation of baryon number and electric charge as a better magnetometer of QCD

This work focuses on the fourth order correlations $χ^{BQ}_{31}$, $χ^{QB}_{31}$, $χ^{BQ}_{22}$, $χ^{BS}_{31}$, $χ^{SB}_{31}$, $χ^{BS}_{22}$, $χ^{QS}_{31}$, $χ^{SQ}_{31}$, $χ^{QS}_{22}$, $χ^{BQS}_{211}$, $χ^{QBS}_{211}$, $χ^{SBQ}_{211}$ of baryon number $B$, electric charge $Q$ and strangeness $S$ at finite temperature, magnetic field and vanishing quark chemical potential. The study is carried out in the framework of a three-flavor PNJL model, considering both cases with and without inverse magnetic catalysis effect. We find that, fourth order correlations $χ^{BQ}_{31}$ at chiral restoration phase transition is more sensitive to the magnetic field than other second order and fourth order correlations and fluctuations, and can be served as a more effective magnetometer of QCD.

nucl-th↗

arXiv2026

$\rho$ mesons in finite magnetic field and finite temperature

The mass spectra of $\rho$ mesons ($\rho_{Q=\pm 1}^{s_z=0,\pm 1}$ and $\rho_{Q=0}^{s_z=0,\pm 1}$) at finite magnetic field and temperature are studied in frame of the two-flavor Nambu-Jona-Lasinio model. Fully considering the breaking of translational invariance induced by external magnetic field, the analytical form of $\rho$ meson propagators have been derived in the Ritus scheme and Schwinger scheme, which gives the same algebraic formula. When solving the pole equation of $\rho$ meson propagators, multiple solutions of the meson mass appear due to the dimension reduction of their constituent quarks in magnetic fields. At vanishing temperature, we focus on the $\rho$ meson masses $M_{\rho}$ corresponding to the lowest value solution of the pole equation. $M_{\rho^{-}_+}$, $M_{\rho^{0}_+}$ and $M_{\rho^{\pm}_0}$ increase with magnetic field. $M_{\rho^{+}_+}$ firstly decreases and then becomes saturated with increasing magnetic field. $M_{\rho^0_0}$ is not sensitive to magnetic field. These results are consistent with the available LQCD simulations. At finite temperature, we discuss the lowest four/five solutions of $\rho$ meson masses $M^{i=0,1,2,3,4}_{\rho}$. With fixed magnetic field, they decrease with temperature, and approach the mass sum of their constituent quarks at high temperature. The mass solution $M^{i}_{\rho}$ for different mesons $\rho_+^{0,\pm}$ and $\rho_0^{0,\pm}$ may become degenerate at finite magnetic field and temperature.

nucl-th↗

arXiv2026

Mass spectra and Mott transitions of neutral mesons at finite temperature and magnetic field in frame of three-flavor Polyakov-extended Nambu-Jona-Lasino model

Mass spectra and Mott transitions of neutral mesons $K_0,{\bar K}_0,π_0,η,η'$ at finite temperature and magnetic field are investigated in a three-flavor PNJL model. We focus on the effect of gluons, which is simulated by the Polyakov potential, and the inverse magnetic catalysis (IMC) effect, which is mimicked by using a magnetic field dependent parameter. Mass spectra show similar structure when introducing the gluon and IMC effect. The mass of $K_0\ ({\bar K}_0)$ meson $m_{K_0}=m_{{\bar K}_0}$ is controlled by chiral symmetry breaking and restoration. It increases with temperature in the low temperature region, and shows a mass jump at the Mott transition. Further increasing temperature, $m_{K_0}$ firstly decreases and then increases with temperature. $π_0$ meson is not only the pseudo-Goldstone boson of chiral symmetry breaking, but also influenced by the flavor mixing of $π_0-η-η'$. The behavior of $m_{π_0}$ is different from $m_{K_0}$ only at high temperature region, which decreases with temperature. $η,η'$ mesons are affected by both the $U_A(1)$ anomaly and the flavor mixing of $π_0-η-η'$. The mass of $η$ meson $m_η$ decreases with temperature in low temperature region and then shows a jump at its Mott transition. After that $m_η$ firstly decreases and later increases with temperature. $η'$ meson is a resonant state, and its mass $m_{η'}$ continuously decreases and then increases with temperature. The mass jumps of $K_0,{\bar K}_0,π_0,η$ mesons are caused by the dimension reduction of the constituent quarks under external magnetic field. In PNJL model, the Mott transition temperature of $K_0,{\bar K}_0,π_0$ mesons ($η$ meson) decreases (increases) with magnetic field. The IMC effect leads to no qualitative change to the meson Mott transition temperature but shifts them to the lower values.

hep-ph↗

arXiv2023

Hyperorder net baryon number fluctuations in nuclear matter at low temperature

We calculate the density fluctuations of net baryon number up to sixth order induced by the interactions of nuclear matter, and explore their relationship with the nuclear liquid-gas phase transition (LGPT), including the stable and metastable phase as well as the region far from the phase transition. The results show that dramatic density fluctuations exist in the vicinity of LGPT, and the hyperorder density fluctuations are more sensitive than the lower order ones to the interactions and structural properties of nuclear matter. The study also indicates that, even far away from the critical region of LGPT, the hadronic interactions can still lead to significant hyperorder density fluctuations. In combination with the chemical freeze-out line fitted from the experimental data, the derived results can be referred to investigate the chiral phase transition, nuclear LGPT, as well as the analysis of related experimental signals.

hep-ph↗

arXiv2023

Stochastic gravitational waves produced by the first-order QCD phase transition

We investigate the stochastic gravitational waves background arising from the first-order QCD chiral phase transition, considering three distinct sources: bubble collisions, sound waves, and fluid turbulence. Within the framework of the Polyakov-Nambu-Jona-Lasinio (PNJL) model, we calculate the parameters governing the intensity of the gravitational wave phase transition and determine their magnitudes along the adiabatic evolutionary path. We introduce the effective bag constant $B_{\mathrm{eff}}$ related to the dynamical evolution of quarks to evaluate the intensity of the phase transition. By calculating expanded potential at the point of false vacuum, we find that all the bubbles are in the mode of runaway, leading the velocity of the bubble wall to the speed of light. The resulting gravitational wave energy spectrum is estimated, revealing a characteristic amplitude of the generated gravitational waves within the centihertz frequency range. We present the gravitational wave spectrum and compare it with the sensitivity range of detectors, and find that the gravitational wave spectra generated by these sources have the potential to be detected by future detectors such as BBO and $μ$ARES.

astro-ph.CO↗