Chiral phase transition in the soft-wall model of AdS/QCD

2017

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Chiral phase transition for three-flavor N f = 2 + 1 QCD with m u = m d = m s is investigated in a modified soft-wall holographic QCD model. Solving temperature dependent chiral condensates from equations of motion of the modified soft-wall model, we extract the quark mass dependence of the order of chiral phase transition in the case of N f = 2 + 1, and the result is in agreement with the "Columbia Plot", which is summarized from lattice simulations and other non-perturbative methods. First order phase transition is observed around the three flavor chiral limit m u/d = 0, m s = 0, while at sufficient large quark masses it turns to be a crossover phase transition. The first order and crossover regions are separated by a second order phase transition line. The second order line is divided into two parts by the m u/d = m s line, and the m s dependence of the transition temperature in these two parts are totally contrast, which might indicate that the two parts are governed by different universality classes.

Section: Jhep02(2017)042mentioning

confidence: 99%

Section: Jhep02(2017)042mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Chiral phase transition of QCD with N f = 2 + 1 flavors from holography

2017

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Critical exponents of finite temperature chiral phase transition in soft-wall AdS/QCD models

Chen

et al. 2019

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Criticality of chiral phase transition at finite temperature is investigated in a soft-wall AdS/QCD model with SU L (N f ) × SU R (N f ) symmetry, especially for N f = 2, 3 and N f = 2 + 1. It is shown that in quark mass plane(m u/d − m s ) chiral phase transition is second order at a certain critical line, by which the whole plane is divided into first order and crossover regions. The critical exponents β and δ, describing critical behavior of chiral condensate along temperature axis and light quark mass axis, are extracted both numerically and analytically. The model gives the critical exponents of the values β = 1 2 , δ = 3 and β = 1 3 , δ = 3 for N f = 2 and N f = 3 respectively. For N f = 2 + 1, in small strange quark mass(m s ) region, the phase transitions for strange quark and u/d quarks are strongly coupled, and the critical exponents are β = 1 3 , δ = 3; when m s is larger than m s,t = 0.290GeV, the dynamics of light flavors(u, d) and strange quarks decoupled and the critical exponents forūu anddd becomes β = 1 2 , δ = 3, exactly the same as N f = 2 result and the mean field result of 3D Ising model; between the two segments, there is a tri-critical point at m s,t = 0.290GeV, at which β = 0.250, δ = 4.975. In some sense, the current results is still at mean field level, and we also showed the possibility to go beyond mean field approximation by including the higher power of scalar potential and the temperature dependence of dilaton field, which might be reasonable in a full back-reaction model. The current study might also provide reasonable constraints on constructing a realistic holographic QCD model, which could describe both chiral dynamics and gluedynamics correctly.

Inverse magnetic catalysis in the soft-wall model of AdS/QCD

Yang

et al. 2017

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Magnetic effects on chiral phase transition have been investigated in a modified soft-wall AdS/QCD model, in which the dilaton field is taken to be negative at the ultraviolet region and positive at the infrared region as in Phys. Rev. D 93 (2016) 101901 and JHEP 04 (2016) 036. The magnetic field is introduced into the background geometry by solving the Einstein-Maxwell system. After embedding the magnetized background geometry into the modified soft-wall model, the magnetic field dependent behavior of chiral condensate is worked out numerically. It is found that, in the chiral limit, the chiral phase transition remains as a second order at finite magnetic field B, while the symmetry restoration temperature and chiral condensate decrease with the increasing of magnetic field in small B region. When including finite quark mass effect, the phase transition turns to be a crossover one, and the transition temperature still decreases with increasing magnetic field B when B is not very large. In this sense, inverse magnetic catalysis effect is observed in this modified soft-wall AdS/QCD model.