569 research outputs found
Equilibration in low-dimensional quantum matrix models
Matrix models play an important role in studies of quantum gravity, being
candidates for a formulation of M-theory, but are notoriously difficult to
solve. In this work, we present a fresh approach by introducing a novel exact
model provably equivalent with low-dimensional bosonic matrix models. In this
equivalent model significant local structure becomes apparent and it can serve
as a simple toy model for analytical and precise numerical study. We derive a
substantial part of the low energy spectrum, find a conserved charge, and are
able to derive numerically the Regge trajectories. To exemplify the usefulness
of the approach, we address questions of equilibration starting from a
non-equilibrium situation, building upon an intuition from quantum information.
We finally discuss possible generalizations of the approach.Comment: 5+2 pages, 2 figures; v2: published versio
Generalized Conformal Symmetry and Oblique AdS/CFT Correspondence for Matrix Theory
The large N behavior of Matrix theory is discussed on the basis of the
previously proposed generalized conformal symmetry. The concept of `oblique'
AdS/CFT correspondence, in which the conformal symmetry involves both the
space-time coordinates and the string coupling constant, is proposed. Based on
the explicit predictions for two-point correlators, possible implications for
the Matrix-theory conjecture are discussed.Comment: LaTeX, 10 pages, 2 figures, written version of the talk presented at
Strings'9
Triple-horizon spherically symmetric spacetime and holographic principle
We present a family of spherically symmetric spacetimes, specified by the
density profile of a vacuum dark energy, which have the same global structure
as the de Sitter spacetime but the reduced symmetry which leads to a
time-evolving and spatially inhomogeneous cosmological term. It connects
smoothly two de Sitter vacua with different values of cosmological constant and
corresponds to anisotropic vacuum dark fluid defined by symmetry of its
stress-energy tensor which is invariant under the radial boosts. This family
contains a special class distinguished by dynamics of evaporation of a
cosmological horizon which evolves to the triple horizon with the finite
entropy, zero temperature, zero curvature, infinite positive specific heat, and
infinite scrambling time. Non-zero value of the cosmological constant in the
triple-horizon spacetime is tightly fixed by quantum dynamics of evaporation of
the cosmological horizon.Comment: Honorable Mentioned Essay - Gravity Research Foundation 2012;
submitted to Int. J. Mod. Phys.
Fully gapped pairing state in spin-triplet superconductor UTe
Spin-triplet superconductors provide an ideal platform for realizing
topological superconductivity with emergent Majorana quasiparticles. The
promising candidate is the recently discovered superconductor UTe, but the
symmetry of the superconducting order parameter remains highly controversial.
Here we determine the superconducting gap structure by the thermal conductivity
of ultra-clean UTe single crystals. We find that the axis thermal
conductivity divided by temperature in zero-temperature limit is
vanishingly small for both magnetic fields and
axes up to , demonstrating the absence of any types of nodes
around axis contrary to the previous belief. The present results, combined
with the reduction of the NMR Knight shift in the superconducting state,
indicate that the superconducting order parameter belongs to the isotropic
representation with a fully gapped pairing state, analogous to the B
phase of superfluid He. These findings reveal that UTe is likely to
be a long-sought three-dimensional (3D) strong topological superconductor
characterized by a 3D winding number, hosting helical Majorana surface states
on any crystal plane.Comment: 10pages, 4 figure
Anisotropic scale invariant cosmology
We study a possibility of anisotropic scale invariant cosmology. It is shown
that within the conventional Einstein gravity, the violation of the null energy
condition is necessary. We construct an example based on a ghost condensation
model that violates the null energy condition. The cosmological solution
necessarily contains at least one contracting spatial direction as in the
Kasner solution. Our cosmology is conjectured to be dual to, if any, a
non-unitary anisotropic scale invariant Euclidean field theory. We investigate
simple correlation functions of the dual theory by using the holographic
computation. After compactification of the contracting direction, our setup may
yield a dual field theory description of the winding tachyon condensation that
might solve the singularity of big bang/crunch of the universe.Comment: 12 pages, v2: reference adde
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