Holographic description of chiral symmetry breaking in a magnetic field in 2+1 dimensions with an improved dilaton

¹ Instituto de Física, Universidade Federal do Rio de Janeiro - 21.941-972 Rio de Janeiro- RJ, Brazil
² Department of Physics and Siyuan Laboratory, Jinan University - Guangzhou 510632, China
³ Departamento de Física and Mestrado Profissional em Práticas da Educação Básica (MPPEB), Colégio Pedro II - 20.921-903 Rio de Janeiro- RJ, Brazil

^(a) diegomr@if.ufrj.br
^(b) lidanning@jnu.edu.cn
^(c) educapossoli@if.ufrj.br
^(d) boschi@if.ufrj.br

Received: 15 September 2019
Accepted: 2 January 2020

Abstract

We consider a holographic description of the chiral symmetry breaking in an external magnetic field in -dimensional gauge theories from the softwall model using an improved dilaton field profile given by . We find inverse magnetic catalysis for B < B_c and magnetic catalysis for B > B_c, where B_c is the pseudocritical magnetic field. The transition between these two regimes is a crossover and occurs at , which depends on the fermion mass and temperature. We also find spontaneous chiral symmetry breaking (the chiral condensate ) at T = 0 in the chiral limit () and chiral symmetry restoration for finite temperatures. We observe that changing the k parameter of the dilaton profile only affects the overall scales of the system such as B_c and σ. For instance, by increasing k one sees an increase of B_c andσ. This suggests that increasing the parameters k₁ and k₂ will decrease the values of B_c and σ.