46,304 research outputs found
Effective Actions for 0+1 Dimensional Scalar QED and its SUSY Generalization at
We compute the effective actions for the 0+1 dimensional scalar field
interacting with an Abelian gauge background, as well as for its supersymmetric
generalization at finite temperature.Comment: 5 pages, Latex fil
The pointing errors of geosynchronous satellites
A study of the correlation between cloud motion and wind field was initiated. Cloud heights and displacements were being obtained from a ceilometer and movie pictures, while winds were measured from pilot balloon observations on a near-simultaneous basis. Cloud motion vectors were obtained from time-lapse cloud pictures, using the WINDCO program, for 27, 28 July, 1969, in the Atlantic. The relationship between observed features of cloud clusters and the ambient wind field derived from cloud trajectories on a wide range of space and time scales is discussed
Quasiadiabatic dynamics of ultracold bosonic atoms in a one-dimensional optical superlattice
We study the quasiadiabatic dynamics of a one-dimensional system of ultracold
bosonic atoms loaded in an optical superlattice. Focusing on a slow linear
variation in time of the superlattice potential, the system is driven from a
conventional Mott insulator phase to a superlattice-induced Mott insulator,
crossing in between a gapless critical superfluid region. Due to the presence
of a gapless region, a number of defects depending on the velocity of the
quench appear. Our findings suggest a power-law dependence similar to the
Kibble-Zurek mechanism for intermediate values of the quench rate. For the
temporal ranges of the quench dynamics that we considered, the scaling of
defects depends nontrivially on the width of the superfluid region.Comment: 6 Pages, 4 Figure
3D Weak Gravitational Lensing of the CMB and Galaxies
In this paper we present a power spectrum formalism that combines the full
three-dimensional information from the galaxy ellipticity field, with
information from the cosmic microwave background (CMB). We include in this
approach galaxy cosmic shear and galaxy intrinsic alignments, CMB deflection,
CMB temperature and CMB polarisation data; including the inter-datum power
spectra between all quantities. We apply this to forecasting cosmological
parameter errors for CMB and imaging surveys for Euclid-like, Planck, ACTPoL,
and CoRE-like experiments. We show that the additional covariance between the
CMB and ellipticity measurements can improve dark energy equation of state
measurements by 15%, and the combination of cosmic shear and the CMB, from
Euclid-like and CoRE-like experiments, could in principle measure the sum of
neutrino masses with an error of 0.003 eV.Comment: Accepted to MNRA
Derivative expansion and large gauge invariance at finite temperature
We study the 0+1 dimensional Chern-Simons theory at finite temperature within
the framework of derivative expansion. We obtain various interesting relations,
solve the theory within this framework and argue that the derivative expansion
is not a suitable formalism for a study of the question of large gauge
invariance.Comment: 12 pages, Late
Stable two--brane models with bulk tachyon matter
We explore the possibility of constructing stable, warped two--brane models
which solve the hierarchy problem, with a bulk non--canonical scalar field
(tachyon matter) as the source term in the action. Among our examples are two
models--one with a warp factor (denoted as ) which differs
from that of the standard Randall--Sundrum by the addition of a quadratic piece
in the and another, where the warping is super-exponential. We
investigate the issue of resolution of hierarchy and perform a stability
analysis by obtaining the effective inter-brane potentials, in each case. Our
analysis reveals that there does exist stable values of the modulus consistent
with hierarchy resolution in both the models. Thus, these models, in which the
bulk scalar field generates the geometry and also ensures stability, provide
viable alternatives to the standard Randall--Sundrum two-brane scenario.Comment: Final version published in Int. Jr. Mod. Phys
Experimental and materials considerations for the topological superconducting state in electron and hole doped semiconductors: searching for non-Abelian Majorana modes in 1D nanowires and 2D heterostructures
In proximity to an s-wave superconductor, a one- or two-dimensional,
electron- or hole-doped semiconductor with a sizable spin-orbit coupling and a
Zeeman splitting can support a topological superconducting (TS) state. The
semiconductor TS state has Majorana fermions as localized zero-energy
excitations at order parameter defects such as vortices and sample edges. Here
we examine the effects of quenched disorder from the semiconductor surface on
the stability of the TS state in both electron- and hole-doped semiconductors.
By considering the interplay of broken time reversal symmetry (due to Zeeman
splitting) and disorder we derive an expression for the disorder suppression of
the superconducting quasiparticle gap in the TS state. We conclude that the
effects of disorder can be minimized by increasing the ratio of the spin-orbit
energy with the Zeeman splitting. By giving explicit numbers we show that a
stable TS state is possible in both electron- and hole-doped semiconductors for
experimentally realistic values of parameters. We discuss possible suitable
semiconductor materials which should be the leading candidates for the Majorana
search in solid state systems.Comment: 11 pages, 2 figures: v3 published versio
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