572 research outputs found
Supergravity backgrounds for deformations of AdS_n x S^n supercoset string models
We consider type IIB supergravity backgrounds corresponding to the deformed
AdS_n x S^n supercoset string models of the type constructed in arXiv:1309.5850
which depend on one deformation parameter \k. In AdS_2 x S^2 case we find that
the deformed metric can be extended to a full supergravity solution with
non-trivial dilaton, RR scalar and RR 5-form strength. The solution depends on
a free parameter (called a) that should be chosen as a particular function of
\k to correspond to the deformed supercoset model. In AdS_3 x S^3 case the full
solution supported by the dilaton, RR scalar and RR 3-form strength exists only
in the two special cases of a=0 and a=1. We conjecture that there may be a more
general one-parameter solution supported by several RR fields that for
particular a=a(\k) corresponds to the supercoset model. In the most complicated
deformed AdS_5 x S^5 case we were able to find only the expressions for the
dilaton and the RR scalar. The full solution is likely to be supported by a
combination of the 5-form and 3-form RR field strengths. We comment on the
singularity structure of the resulting metric and exact dilaton field.Comment: 22 pages; v2,v3: appendix A expanded and correcte
Effects of a fundamental mass term in two-dimensional super Yang-Mills theory
We show that adding a vacuum expectation value to a gauge field left over
from a dimensional reduction of three-dimensional pure supersymmetric
Yang-Mills theory generates mass terms for the fundamental fields in the
two-dimensional theory while supersymmetry stays intact. This is similar to the
adjoint mass term that is generated by a Chern-Simons term in this theory. We
study the spectrum of the two-dimensional theory as a function of the vacuum
expectation value and of the Chern-Simons coupling. Apart from some symmetry
issues a straightforward picture arises. We show that at least one massless
state exists if the Chern-Simons coupling vanishes. The numerical spectrum
separates into (almost) massless and very heavy states as the Chern-Simons
coupling grows. We present evidence that the gap survives the continuum limit.
We display structure functions and other properties of some of the bound
states.Comment: 17 pp., 10 figs; substantially revised version to be published in
Phys. Rev.
N=(1,1) super Yang--Mills theory in 1+1 dimensions at finite temperature
We present a formulation of N=(1,1) super Yang-Mills theory in 1+1 dimensions
at finite temperature. The partition function is constructed by finding a
numerical approximation to the entire spectrum. We solve numerically for the
spectrum using Supersymmetric Discrete Light-Cone Quantization (SDLCQ) in the
large-N_c approximation and calculate the density of states. We find that the
density of states grows exponentially and the theory has a Hagedorn
temperature, which we extract. We find that the Hagedorn temperature at
infinite resolution is slightly less than one in units of (g^(2) N_c/pi)^(1/2).
We use the density of states to also calculate a standard set of thermodynamic
functions below the Hagedorn temperature. In this temperature range, we find
that the thermodynamics is dominated by the massless states of the theory.Comment: 16 pages, 8 eps figures, LaTe
Spectral Degeneracy in Supersymmetric Gluodynamics and One-Flavor QCD related to N=1/2 SUSY
In supersymmetric gluodynamics (N=1 super-Yang-Mills theory) we show that the
spectral functions induced by the nonchiral operator Tr G_{\alpha\beta}
\bar\lambda^2 are fully degenerate in the J^{PC}=1^{\pm -} channels. The above
operator is related to N=1/2 generalization of SUSY. Using the planar
equivalence, this translates into the statement of degeneracy between the
mesons produced from the vacuum by the operators (\bar \Psi \vec E\Psi + i\bar
\Psi \vec B \gamma^5\Psi) and (\bar \Psi \vec B\Psi - i\bar \Psi \vec E
\gamma^5\Psi) in one-flavor QCD, up to 1/N corrections. Here \Psi is the quark
field, and \vec E ,\vec B are chromoelectric/chromomagnetic fields,
respectively.Comment: Latex, 6 pages, two references adde
General 2 charge geometries
Two charge BPS horizon free supergravity geometries are important in
proposals for understanding black hole microstates. In this paper we construct
a new class of geometries in the NS1-P system, corresponding to solitonic
strings carrying fermionic as well as bosonic condensates. Such geometries are
required to account for the full microscopic entropy of the NS1-P system. We
then briefly discuss the properties of the corresponding geometries in the dual
D1-D5 system.Comment: 44 page
Very high quality factor measured in annealed fused silica
We present the results of quality factor measurements for rod samples made of
fused silica. To decrease the dissipation we annealed our samples. The highest
quality factor that we observed was for a mode at
384 Hz. This is the highest published value of in fused silica measured to
date.Comment: 8 pages, 2 figure
Excitations in the deformed D1D5 CFT
We perform some simple computations for the first order deformation of the
D1D5 CFT off its orbifold point. It had been shown earlier that under this
deformation the vacuum state changes to a squeezed state (with the further
action of a supercharge). We now start with states containing one or two
initial quanta and write down the corresponding states obtained under the
action of deformation operator. The result is relevant to the evolution of an
initial excitation in the CFT dual to the near extremal D1D5 black hole: when a
left and a right moving excitation collide in the CFT, the deformation operator
spreads their energy over a larger number of quanta, thus evolving the state
towards the infrared.Comment: 26 pages, Latex, 4 figure
S-matrix for magnons in the D1-D5 system
We show that integrability and symmetries of the near horizon geometry of the
D1-D5 system determine the S-matrix for the scattering of magnons with
polarizations in AdS3 S3 completely up to a phase. Using
semi-classical methods we evaluate the phase to the leading and to the one-loop
approximation in the strong coupling expansion. We then show that the phase
obeys the unitarity constraint implied by the crossing relations to the
one-loop order. We also verify that the dispersion relation obeyed by these
magnons is one-loop exact at strong coupling which is consistent with their BPS
nature.Comment: 40 pages, Latex, Role of Virasoro constraints clarified, version
matches with published versio
Deforming the D1D5 CFT away from the orbifold point
The D1D5 brane bound state is believed to have an `orbifold point' in its
moduli space which is the analogue of the free Yang Mills theory for the D3
brane bound state. The supergravity geometry generated by D1 and D5 branes is
described by a different point in moduli space, and in moving towards this
point we have to deform the CFT by a marginal operator: the `twist' which links
together two copies of the CFT. In this paper we find the effect of this
deformation operator on the simplest physical state of the CFT -- the Ramond
vacuum. The twist deformation leads to a final state that is populated by pairs
of excitations like those in a squeezed state. We find the coefficients
characterizing the distribution of these particle pairs (for both bosons and
fermions) and thus write this final state in closed form.Comment: 30 pages, 4 figures, Late
Spacetime in String Theory
We give a brief overview of the nature of spacetime emerging from string
theory. This is radically different from the familiar spacetime of Einstein's
relativity. At a perturbative level, the spacetime metric appears as ``coupling
constants" in a two dimensional quantum field theory. Nonperturbatively (with
certain boundary conditions), spacetime is not fundamental but must be
reconstructed from a holographic, dual theory.Comment: 20 pages; references adde
- …