The Fast Life of Holographic Mesons

Holographic techniques are used to study the dispersion relation of meson quasiparticles moving through a thermal plasma in N = 2 super-Yang-Mills theory with N_c colours and coupled to N_f flavours of fundamental matter in the regime N_f/N_c ≪ 1. The meson states are destabilized by introducing a small quark density n_q. Holographic spectral functions are used to investigate the dispersion relations and widths of these quasiparticles. In a low momentum regime q < q_max, the quasiparticles approach a limiting velocity that can be significantly less than the speed of light. In this regime, the widths of the quasiparticles also rise dramatically as the momentum approaches q_max. The spectral functions do not display isolated resonances for q > q_max. However, by studying the dual quasinormal modes one can extend the dispersion relation into this regime. We give a qualitative argument suggesting that the group velocity rises to the speed of light for q ≫ q_max. This contribution provides a summary of the results in [1].