4 research outputs found
Stability of Non-Abelian Black Holes
Two types of self-gravitating particle solutions found in several theories
with non-Abelian fields are smoothly connected by a family of non-trivial black
holes. There exists a maximum point of the black hole entropy, where the
stability of solutions changes. This criterion is universal, and the changes in
stability follow from a catastrophe-theoretic analysis of the potential
function defined by black hole entropy.Comment: 4 Figures to be sent on request,8 pages, WU-AP/33/9
One-Loop Amplitudes in Euclidean Quantum Gravity
This paper studies the linearized gravitational field in the presence of
boundaries. For this purpose, -function regularization is used to
perform the mode-by-mode evaluation of BRST-invariant Faddeev-Popov amplitudes
in the case of flat Euclidean four-space bounded by a three-sphere. On choosing
the de Donder gauge-averaging term, the resulting value is found to
agree with the space-time covariant calculation of the same amplitudes, which
relies on the recently corrected geometric formulas for the asymptotic heat
kernel in the case of mixed boundary conditions. Two sets of mixed boundary
conditions for Euclidean quantum gravity are then compared in detail. The
analysis proves that one cannot restrict the path-integral measure to
transverse-traceless perturbations. By contrast, gauge-invariant amplitudes are
only obtained on considering from the beginning all perturbative modes of the
gravitational field, jointly with ghost modes.Comment: 26 pages, plain TeX, no figure
Chiral bag boundary conditions on the ball
Local boundary conditions for spinor fields are expressed in terms of a
1-parameter family of boundary operators, and find applications ranging from
(supersymmetric) quantum cosmology to the bag model in quantum chromodynamics.
The present paper proves that, for massless spinor fields on the Euclidean ball
in dimensions d=2,4,6, the resulting zeta(0) value is independent of such a
theta parameter, while the various heat-kernel coefficients exhibit a
theta-dependence which is eventually expressed in a simple way through
hyperbolic functions and their integer powers.Comment: 30 pages, REVTe
Strings, p-branes and Skyrmions in curved space
SIGLEAvailable from British Library Document Supply Centre- DSC:DX84887 / BLDSC - British Library Document Supply CentreGBUnited Kingdo