64 research outputs found
A Bohr-Sommerfeld quantization formula for quasinormal frequencies of AdS black holes
We derive a quantization formula of Bohr-Sommerfeld type for computing
quasinormal frequencies for scalar perturbations in an AdS black hole in the
limit of large scalar mass or spatial momentum. We then apply the formula to
find poles in retarded Green functions of boundary CFTs on and
. We find that when the boundary theory is perturbed by an operator
of dimension , the relaxation time back to equilibrium is given at
zero momentum by . Turning on a
large spatial momentum can significantly increase it. For a generic scalar
operator in a CFT on , there exists a sequence of poles near the
lightcone whose imaginary part scales with momentum as
in the large momentum limit. For a CFT on a sphere we show that the
theory possesses a large number of long-lived quasiparticles whose imaginary
part is exponentially small in momentum.Comment: 39 pages, 22 figure
Inheritance principle and Non-renormalization theorems at finite temperature
We present a general proof of an ``inheritance principle'' satisfied by a
weakly coupled SU(N) gauge theory with adjoint matter on a class of compact
manifolds (like ). In the large limit, finite temperature correlation
functions of gauge invariant single-trace operators in the low temperature
phase are related to those at zero temperature by summing over images of each
operator in the Euclidean time direction. As a consequence, various
non-renormalization theorems of \NN=4 Super-Yang-Mills theory on
survive at finite temperature despite the fact that the conformal and
supersymmetries are both broken.Comment: 14 pages, uses harvmac v2: reference added, the role of
hep-th/0505148 emphasize
Instanton Effects in Three Flavor QCD
Recently it was shown that in QCD-like theories with , where
is the number of light flavors and is the number of colors, there are
correlation functions that vanish in perturbation theory and at short distances
receive dominant, calculable contributions from small instantons. Here we
extend the set of such objects to theories with , which includes real
QCD, and discuss their application as a calibration of lattice computations at
small quark mass. We revisit the related issue of the quark mass and its
additive renormalization by small instantons, and discuss an alternative test
of on the lattice.Comment: 22 pages, 2 figures. v3: reordered discussion of finite correlators
and low energy constants, version published in PRD. v2: amended discussion of
calculable vs incalculable effects for $N_f\leq N
Dynamics of the Peccei Quinn Scale
Invoking the Peccei-Quinn (PQ) solution to the strong CP problem substitutes
the puzzle of why is so small with the puzzle of why the PQ
symmetry is of such high quality. Cosmological and astrophysical considerations
raise further puzzles. This paper explores this issues in several contexts:
string theory and field theory, and theories without and with low energy
supersymmetry. Among the questions studied are whether requiring axion dark
matter can account for the quality of the PQ symmetry, to which the answer is
sometimes yes. In non-supersymmetric theories, we find GeV is
quite plausible. In gauge mediation, cosmological constraints on pseudomoduli
place in this range, and require that the gravitino mass be of order an
MeV.Comment: 17 pages, 1 figur
Axions in the Landscape and String Theory
While axions seem ubiquitous in critical string theories, whether they might
survive in any string theoretic description of nature is a difficult question.
With some mild assumptions, one can frame the issues in the case that there is
an approximate supersymmetry below the underlying string scale. The problem of
axions is then closely tied to the question of how moduli are fixed. We
consider, from this viewpoint, the possibility that supersymmetry is broken at
an intermediate scale, as in "gravity mediation," at a low scale, as in gauge
mediation, and at a very high scale, to model the possibility that there is no
low energy supersymmetry. Putative mechanisms for moduli fixing can then be
systematically classified, and at least for intermediate and high scale
breaking, light axions appear plausible. In the course of this work, we are
lead to consider aspects of moduli fixing and supersymmetry breaking, and we
revisit the possibility of very large extra dimensions.Comment: 18 pages; v2, updated and added reference
Supersymmetric Field Theories on Three-Manifolds
We construct supersymmetric field theories on Riemannian three-manifolds M,
focusing on N=2 theories with a U(1)_R symmetry. Our approach is based on the
rigid limit of new minimal supergravity in three dimensions, which couples to
the flat-space supermultiplet containing the R-current and the energy-momentum
tensor. The field theory on M possesses a single supercharge, if and only if M
admits an almost contact metric structure that satisfies a certain
integrability condition. This may lead to global restrictions on M, even though
we can always construct one supercharge on any given patch. We also analyze the
conditions for the presence of additional supercharges. In particular, two
supercharges of opposite R-charge exist on every Seifert manifold. We present
general supersymmetric Lagrangians on M and discuss their flat-space limit,
which can be analyzed using the R-current supermultiplet. As an application, we
show how the flat-space two-point function of the energy-momentum tensor in N=2
superconformal theories can be calculated using localization on a squashed
sphere.Comment: 53 pages; minor change
From Rigid Supersymmetry to Twisted Holomorphic Theories
We study N=1 field theories with a U(1)_R symmetry on compact four-manifolds
M. Supersymmetry requires M to be a complex manifold. The supersymmetric theory
on M can be described in terms of conventional fields coupled to background
supergravity, or in terms of twisted fields adapted to the complex geometry of
M. Many properties of the theory that are difficult to see in one formulation
are simpler in the other one. We use the twisted description to study the
dependence of the partition function Z_M on the geometry of M, as well as
coupling constants and background gauge fields, recovering and extending
previous results. We also indicate how to generalize our analysis to
three-dimensional N=2 theories with a U(1)_R symmetry. In this case
supersymmetry requires M to carry a transversely holomorphic foliation, which
endows it with a near-perfect analogue of complex geometry. Finally, we present
new explicit formulas for the dependence of Z_M on the choice of U(1)_R
symmetry in four and three dimensions, and illustrate them for complex
manifolds diffeomorphic to S^3 x S^1, as well as general squashed
three-spheres.Comment: 55 pages; minor change
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