Thermal properties of light mesons from holography

Abstract

The thermal properties of light mesons, including the temperature dependence of their masses(both screening and pole masses) and thermal widths, are studied in a twoflavor (N f = 2) soft-wall AdS/QCD model. By solving the spatial correlation functions, we extract the screening masses (m scr ) from their poles. The screening masses of pseudo-scalar (pion), axial-vector (a 1 ) mesons increase (almost)monotonically with the temperature, while the screening masses of scalar (σ) and vector (ρ) mesons decrease at low temperatures and increase at high temperatures. Besides, the pole masses (m pole ) and thermal widths (Γ) are worked out from the temporal correlation functions and the corresponding spectral functions. The results indicate that the pole masses have local minimums at low temperatures and grow at high temperatures. The thermal widths grow rapidly above the chiral crossover temperature T cp , indicating the dissociation of mesons at high temperatures. Furthermore, degeneration of chiral partners (pion and σ mesons, ρ and a 1 ) above T cp are observed both from screening masses and pole masses, revealing the restoration of chiral symmetry at the spectral level. Finally, we verify numerically that the spectral functions in the temporal regime are strongly related to the quasi-normal modes with complex frequencies ω 0 = m pole − iΓ/2.

Temperature dependence of $ρ$ meson-nucleon coupling constant from the AdS/QCD soft-wall model

“…This model turned out an effective tool for the calculation of phenomenological hadron quantities ( [9][10][11][12][13][14][15][16][17][18][19]), the phase transition between the hot hadronic matter and the quark-gluon plasma ( [20]), and for the theoretical studies in the hot hadronic matter as well ( [21][22][23][24][25][26][27][28]). The properties of mesons and baryons in the thermal medium have been investigated in the framework of different models including the hard-and soft-wall models of the AdS/QCD bottom-up approach.…”

QCD chiral condensate and pseudoscalar-meson properties in the nuclear medium at finite temperature

“…A phase structure of the strongly interacting matter of quantum chromodynamics (QCD) at nonvanishing temperature and density as well as in the presence of the external magnetic field becomes an interested topic in nuclear physics community in the last few years. In the theory side, many attempts have been done to study the phase-diagram of QCD in the nonvanishing temperature and chemical potential/density , starting from the low density/chemical potential and/or high temperature which is relevant for the early universe phenomena [32] until the low temperature and/or high density/chemical potential, which is relevant to the central core of the neutron star or compact star phenomena [33,34] using several various QCD inspired models [3,6,8,9,[21][22][23][24] with different approaches [8,9,21,26,27] as well as lattice QCD [2,19,25,[28][29][30] and remarkable progresses have been made until today. However, there are some problems to remain, namely, the sign problem [35][36][37], uncertain location of the critical end point (CEP) [38][39][40], and the chiral imbalance [38,41], which is related to the chiral magnetic effect (CME).…”

$a_{1}$ meson-nucleon coupling constant at finite temperature from the soft-wall AdS/QCD model

“…Temperature dependencies of the quantities describing the hadrons in the nuclear medium are investigated in the framework of different approaches and models. The holographic soft-wall model is one of good tools for the studies in the medium and this model was applied for solving different kinds of problems: determining of the temperature influence on in-medium quantities such as screening mass [13], hadron form factors [14][15][16][17], quarkonium [18], decay constants [19],…”