Particle theory

Abstract:

As a non-trivial check of the non-supersymmetric gauge/gravity duality, we use a near-extremal black brane background to compute the retarded Green's functions of the stress-energy tensor in N = 4 super-Yang-Mills (SYM) theory at finite temperature. For the long-distance, low-frequency modes of the diagonal components of the stress-energy tensor, hydrodynamics predicts the existence of a pole in the correlators corresponding to propagation of sound waves in the N = 4 SYM plasma. The retarded Green's functions obtained from gravity do indeed exhibit this pole, with the correct values for the sound speed and the rate of attenuation. © SISSA/ISAS 2003.

Abstract:

We investigate the properties of the deconfinement transition in SU(4) and SU(6) gauge theories. We find that it is a 'normal' first order transition in both cases, from which we conclude that the transition is first order in the N → ∞ limit. Comparing our preliminary estimates of the continuum values of Tc/√σ with existing values for SU(2) and SU(3) demonstrates a weak dependence on N for all values of N. © 2002 Published by Elsevier Science B.V.

Abstract:

Rapporteur talk at the Lepton-Photon Conference, Rome, July 2001: reviewing the evidence and strategies for understanding scalar mesons, glueballs and hybrids, the gluonic Pomeron and the interplay of heavy flavours and light hadron dynamics. Dedicated to the memory of Nathan Isgur, long-time collaborator and friend, whose original ideas in hadron spectroscopy formed the basis for much of the talk.