From string theory to large N QCD

TL;DR

This paper constructs a holographic dual for a non-conformal gauge theory with running couplings, analyzing its thermodynamics, confinement, and quark behavior at various temperatures using supergravity methods.

Contribution

It introduces a dual geometry combining Klebanov-Witten and Klebanov-Strassler features, providing a framework for studying non-conformal gauge theories with matter and temperature effects.

Findings

Computed thermal mass, drag, and diffusion coefficients for quarks.

Calculated shear viscosity and its ratio to entropy density.

Demonstrated confinement and quarkonium melting at different temperatures.

Abstract

We propose the dual gravity of a non conformal gauge theory which has logarithmic running of couplings in the IR but becomes almost conformal in the far UV. The theory has matter in fundamental representation, non-zero temperature and under a cascade of Seiberg dualities, can be described in terms of gauge groups of lower and lower rank. We outline the procedure of holographic renormalization and propose a mechanism to UV complete the gauge theory by modifying the dual geometry at large radial distances. As an example, we construct the brane configuration and sources required to attach a Klebanov-Witten type geometry at large r to a Klebanov- Strassler type geometry at small r. Using the supergravity description for the dual geometry, we compute thermal mass of a fundamental 'quark' in our theory along with drag and diffusion coefficients of the gauge theory plasma. We compute the stress tensor of the gauge theory and formulate the wake a probe leaves behind as it traverses the medium. Transport coefficient shear viscosity {\eta} and its ratio to entropy {\eta}/s are calculated and finally we show how confinement of 'quarks' at large separation can occur at low temperatures. We classify the most general dual geometry that gives rise to linear confinement at low temperatures and show how quarkonium states can melt at high temperatures to liberate 'quarks'.