Particle theory

Abstract:

At a formal level, there appears to be no difficulty involved in introducing a chemical potential for a globally conserved quantum number into the partition function for space-time including a black hole. Were this possible, however, it would provide a form of black hole hair, and contradict the idea that global quantum numbers are violated in black hole evaporation. We demonstrate dynamical mechanisms that negate the formal procedure, both for topological charge (Skyrmions) and complex scalar-field charge. Skyrmions collapse to the horizon; scalar-field charge fluctuates uncontrollably.

Abstract:

The large N limit of SU(N) gauge theories in 3+1 dimensions is investigated on the lattice by extrapolating results obtained for 2 ≤ N ≤ 5. A numerical determination of the masses of the lowest-lying glueball states and of the topological susceptibility in the limit N → ∞ is provided. Ratios of the tensions of stable κ-strings over the tension of the fundamental string are investigated in various regimes and the results are compared with expectations based on several scenarios - in particular MQCD and Casimir scaling. While not conclusive at zero temperature in D=3+1, in the other cases investigated our data seem to favour the latter.