Flavours and infra-red instability in holography

Abstract

With a simple gravitational model in five dimensions, defined by Einsteingravity with a negative cosmological constant, coupled to a Dirac-Born-Infeld and a ChernSimons term, we explore the fate of BF-bound violation for a probe scalar field and a fluctuation mode of the corresponding geometry. We assume this simple model to capture the dynamics of a strongly coupled SU(N c ) gauge theory with N f fundamental matter, which in the limit O (N c ) ∼ O (N f ) and with a non-vanishing matter density, is holographically described by an AdS 2 -geometry in the IR. We demonstrate that, superconductor/superfluid instabilities are facilitated and spontaneous breaking of translational invariance is inhibited with increasing values of (N f /N c ). This is similar, in spirit, with known results in large N c Quantum Chromodynamics with N f quarks and a non-vanishing density, in which the chiral density wave phase becomes suppressed and superconducting instabilities become favoured as the number of quarks is increased.

On aspects of holographic thermal QCD at finite coupling

“…The pioneer work on this was done by [32] where D7 brans were embedded in the AdS geometry in the probe limit to ignore the back reaction on the target space. A variety of interesting issues has been looked upon with flavor branes using gauge/gravity duality in [33] [34] [35] [36].…”

Scale invariance with fundamental matters and anomaly: a holographic description

“…We intend to explore the solution space of the proposed action. The primary motivation for the inclusion of a Chern-Simons term can be drawn from the observation made in [10], in which it was demonstrated that, by tuning the parameter (N f /N c ), one may interpolate between a spatial modulation instability and a superconducting instability, similar to the physics of QCD at large N c and large N f [11]. Thus, we will treat the Newton's constant, the putative brane tension and the Chern-Simons coefficients which appear in defining the action of the theory to be free, and we will explore the nature of various exact analytical solutions, as one varies these parameters.…”