The fast life of holographic mesons

TL;DR

This paper investigates the behavior of holographic meson quasiparticles in a thermal plasma using gauge/gravity duality, revealing velocity limits, spectral properties, and high-momentum dynamics in a strongly coupled gauge theory.

Contribution

It provides a detailed analysis of meson quasiparticle dispersion, stability, and spectral functions at finite density in a holographic setting, extending understanding of high-momentum behavior.

Findings

Quasiparticles have a limiting velocity less than the speed of light at low momentum.

Widths of quasiparticles increase dramatically near a critical momentum.

Dispersion relations extend into high-momentum regimes via quasinormal modes.

Abstract

We use holographic techniques to study meson quasiparticles moving through a thermal plasma in N=2 super-Yang-Mills theory, with gauge group SU(N_c) and coupled to N_f flavours of fundamental matter. This holographic approach reliably describes the system at large N_c, large 't Hooft coupling and N_f/N_c<<1. The meson states are destabilized by introducing a small quark density n_q. Spectral functions are used to examine the dispersion relations of these quasiparticles. In a low-momentum regime, the quasiparticles approach a limiting velocity which can be significantly less than the speed of light. In this regime, the widths of the quasiparticles also rise dramatically as their momentum approaches a critical value q_crit. While the spectral functions do not display isolated resonances for q>q_crit, the dispersion relations can be extended into this high-momentum regime by studying the dual quasinormal modes. A preliminary qualitative analysis of these modes suggests that the group velocity rises to the speed of light for q>>q_crit.