Magnetic catalysis and inverse catalysis for heavy pions

Abstract

We investigate the QCD phase diagram for nonzero background magnetic fields using first-principles lattice simulations. At the physical point (in terms of quark masses), the thermodynamics of this system is controlled by two opposing effects: magnetic catalysis (enhancement of the quark condensate) at low temperature and inverse magnetic catalysis (reduction of the condensate) in the transition region. While the former is known to be robust and independent of the details of the interactions, inverse catalysis arises as a result of a delicate competition, effective only for light quarks. By performing simulations at different quark masses, we determine the pion mass above which inverse catalysis does not take place in the transition region anymore. Even for pions heavier than this limiting value -where the quark condensate undergoes magnetic catalysis -our results are consistent with the notion that the transition temperature is reduced by the magnetic field. These findings will be useful to guide low-energy models and effective theories of QCD.

Magnetized baryons and the QCD phase diagram: NJL model meets the lattice

“…This mechanism is suppressed if quarks are heavy. Indeed, contrary to the situation at the physical point, for sufficiently heavy quarks (M π 500 MeV), inverse magnetic catalysis does not occur anymore [17] -nevertheless, the transition temperature is still reduced by B [18].…”

Thermodynamics of 2+1 flavor Polyakov-loop quark-meson model under external magnetic field

“…[68] to use the temperaturedependent masses and then include additional logarithm terms in Eq. (30), which are vanishing in the original calculation. These temperature-dependent masses m f (b) (T ) and Polyakov-loop Φ(T ) can be obtained from FRG approach, we can thus substitute the results into the above formulas and do the integrals numerically.…”

“…Magnetic susceptibility χ(T ) has also been studied by combining the FRG approach with the non-interacting gas approximation in Refs. [68,103], in which the whole system is approximated as non-interacting quark and (pseudo-)scalar meson gases [30]. χ(T ) can then be separated into two parts, namely…”

“…It has been well known that the equation of state (EoS) and the entropy density can represent well the properties of a matter. Then the EoS and the entropy density of the strong interaction matter in an external magnetic field have been studied with the lattice QCD simulations [27][28][29], Hadron Resonance Gas (HRG) model [30], quark-meson (QM) model [67,68,88] and Polyakov-loop improved quark-meson (PQM) model [10-13, 59, 89-93]. However, the mechanism of the magnetic field effect on the QCD system has not yet been fully understood by analyzing the thermodynamical properties concretely.…”

Constraining the hadron-quark phase transition chemical potential via astronomical observation

“…Meanwhile general analysis and effective QCD models have also played the important role and made significant progress (see, e.g., Refs. [4,5,6,57,58,59,60,61,62,63,64,65,66]).…”