7 research outputs found
The generalized chiral Schwinger model on the two-sphere
A family of theories which interpolate between vector and chiral Schwinger
models is studied on the two--sphere . The conflict between the loss of
gauge invariance and global geometrical properties is solved by introducing a
fixed background connection. In this way the generalized Dirac--Weyl operator
can be globally defined on . The generating functional of the Green
functions is obtained by taking carefully into account the contribution of
gauge fields with non--trivial topological charge and of the related
zero--modes of the Dirac determinant. In the decompactification limit, the
Green functions of the flat case are recovered; in particular the fermionic
condensate in the vacuum vanishes, at variance with its behaviour in the vector
Schwinger model.Comment: 39 pages, latex, no figure
Quantum gravity corrections to the Schwarzschild mass
Vacuum spherically symmetric Einstein gravity in dimensions can be
cast in a two-dimensional conformal nonlinear sigma model form by first
integrating on the -dimensional (hyper)sphere and then performing a
canonical transformation. The conformal sigma model is described by two fields
which are related to the Arnowitt-Deser-Misner mass and to the radius of the
-dimensional (hyper)sphere, respectively. By quantizing perturbatively
the theory we estimate the quantum corrections to the ADM mass of a black hole.Comment: 18 pages, 8 figures, LaTeX2e, uses epsfig package, accepted for
publication in Phys. Rev.
Renormalization Group Study of Chern-Simons Field Coupled to Scalar Matter in a Modified BPHZ Subtraction Scheme
We apply a soft version of the BPHZ subtraction scheme to the computation of
two-loop corrections from an Abelian Chern-Simons field coupled to (massive)
scalar matter with a and
self-interactions. The two-loop renormalization group functions are calculated.
We compare our results with those in the literature.Comment: 15 pages, 7 figures, revtex. To appear in Phys. Rev.
Non-equilibrium Condensation Process in a Holographic Superconductor
We study the non-equilibrium condensation process in a holographic
superconductor. When the temperature T is smaller than a critical temperature
T_c, there are two black hole solutions, the Reissner-Nordstrom-AdS black hole
and a black hole with a scalar hair. In the boundary theory, they can be
regarded as the supercooled normal phase and the superconducting phase,
respectively. We consider perturbations on supercooled Reissner-Nordstrom-AdS
black holes and study their non-linear time evolution to know about physical
phenomena associated with rapidly-cooled superconductors. We find that, for
T<T_c, the initial perturbations grow exponentially and, eventually, spacetimes
approach the hairy black holes. We also clarify how the relaxation process from
a far-from-equilibrium state proceeds in the boundary theory by observing the
time dependence of the superconducting order parameter. Finally, we study the
time evolution of event and apparent horizons and discuss their correspondence
with the entropy of the boundary theory. Our result gives a first step toward
the holographic understanding of the non-equilibrium process in
superconductors.Comment: 20 pages, 7 figure