Chiral symmetry breaking transitions in holographic duals.
University of Southampton, Faculty of Physical and Applied Sciences,
Generalisations of the AdS/CFT Correspondence are used to study chiral symmetry breaking in dual gauge theories. We use the D3/D7 and D3/D5 systems to model both 3+1 and 2+1 dimensional, strongly coupled, gauge theories with quark fields. We show that chiral symmetry breaking is induced by either an imposed running coupling/dilaton profile or a background magnetic field. We explore the low energy effective theory of the pions of these models deriving simple integral equations for low energy parameters in the spirit of constituent quark model results. We also explore the phase structure of these models, with respect to
temperature, chemical potential and applied electric field. The phase diagrams contain regions with broken and restored chiral symmetry separated by first order, second order and BKT transitions. There is an extra transition associated with the melting of the meson states into the background plasma. Finally we use the phenomenological dilaton profile to engineer holographic descriptions of theories with QCD-like phase diagrams.
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