Inverse magnetic catalysis from improved holographic QCD in the Veneziano limit

• Published in: The journal of high energy physics 2017-03, Vol.2017 (3), p.1-22, Article 53
• Main Authors: Gürsoy, Umut, Iatrakis, Ioannis, Järvinen, Matti, Nijs, Govert
• Format: Article
• Language: English
• Subjects: Catalysis; Classical and Quantum Gravitation; Condensates; Elementary Particles; Flavor (particle physics); Flavours; High energy physics; High Energy Physics - Phenomenology; High Energy Physics - Theory; Inverse; Magnetic fields; Mathematical models; Nuclear Theory; Physics; Physics and Astronomy; Quantum chromodynamics; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; String Theory
• ISSN: 1029-8479; 1126-6708; 1029-8479
• DOI: 10.1007/JHEP03(2017)053

A bstract We study the dependence of the chiral condensate on external magnetic field in the context of holographic QCD at large number of flavors. We consider a holographic QCD model where the flavor degrees of freedom fully backreact on the color dynamics. Perturbative QCD calculations have shown that B acts constructively on the chiral condensate, a phenomenon called “magnetic catalysis”. In contrast, recent lattice calculations show that, depending on the number of flavors and temperature, the magnetic field may also act destructively, which is called “inverse magnetic catalysis”. Here we show that the holographic theory is capable of both behaviors depending on the choice of parameters. For reasonable choice of the potentials entering the model we find qualitative agreement with the lattice expectations. Our results provide insight for the physical reasons behind the inverse magnetic catalysis. In particular, we argue that the backreaction of the flavors to the background geometry decatalyzes the condensate.