Inverse magnetic catalysis and the Polyakov loop

By F. Bruckmann, Gergely Endrodi, T. Kovács. 2013

201 citations recorded by the source corpus.

A bstractWe study the physical mechanism of how an external magnetic field influences the QCD quark condensate. Two competing mechanisms are identified, both relying on the interaction between the magnetic field and the low quark modes. While the coupling to valence quarks enhances the condensate, the interaction with sea quarks suppresses it in the transition region. The latter “sea effect” acts by ordering the Polyakov loop and, thereby, reduces the number of small Dirac eigenmodes and the condensate. It is most effective around the transition temperature, where the Polyakov loop effective potential is flat and a small correction to it by the magnetic field can have a significant effect. Around the critical temperature, the sea suppression overwhelms the valence enhancement, resulting in a net suppression of the condensate, named inverse magnetic catalysis. We support this physical picture by lattice simulations including continuum extrapolated results on the Polyakov loop as a function of temperature and magnetic field. We argue that taking into account the increase in the Polyakov loop and its interaction with the low-lying modes is essential to obtain the full physical picture, and should be incorporated in effective models for the description of QCD in magnetic fields in the transition region.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7d71097547146f42e289449039d1b5dcd9386853

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In Nuclear and High Energy Physics

Citations in the corpus

The QCD equation of state in background magnetic fields (2014, background): “This analysis indicates that the transition temperature decreases as B grows, in agreement with our previous results where other thermodynamic observables (light quark condensate, strange quark number susceptibility and Polyakov loop) were used [16, 17].”
QCD at finite temperature and chemical potential from Dyson–Schwinger equations (2018, background): “Perhaps surprisingly, results from lattice QCD also demonstrate that the opposite effect happens for large enough temperatures: the dynamical mass generation is reduced and consequently the transition temperatures for the crossover to the chirally restored phase is decreased [76–80].”