7,643 research outputs found
Electromagnetic and thermal responses in topological matter: topological terms, quantum anomalies and D-branes
We discuss the thermal (or gravitational) responses in topological
superconductors and in topological phases in general. Such thermal responses
(as well as electromagnetic responses for conserved charge) provide a
definition of topological insulators and superconductors beyond the
single-particle picture. In two-dimensional topological phases, the Str\v{e}da
formula for the electric Hall conductivity is generalized to the thermal Hall
conductivity. Applying this formula to the Majorana surface states of
three-dimensional topological superconductors predicts cross-correlated
responses between the angular momentum and thermal polarization (entropy
polarization). We also discuss a use of D-branes in string theory as a
systematic tool to derive all such topological terms and topological responses.
In particular, we relate the index of topological insulators
introduced by Kane and Mele (and its generalization to other symmetry classes
and to arbitrary dimensions) to the K-theory charge of non-BPS D-branes, and
vice versa. We thus establish a link between the stability of non-BPS D-branes
and the topological stability of topological insulators.Comment: 16 pages, 2 figures; Submitted to a topical issue of the Comptes
Rendus de l Academie des Sciences (CRAS
Nonlocality, No-Signalling and Bell's Theorem investigated by Weyl's Conformal Differential Geometry
The principles and methods of the Conformal Quantum Geometrodynamics (CQG)
based on the Weyl's differential geometry are presented. The theory applied to
the case of the relativistic single quantum spin 1/2 leads a novel and
unconventional derivation of Dirac's equation. The further extension of the
theory to the case of two spins 1/2 in EPR entangled state and to the related
violation of Bell's inequalities leads, by an exact albeit non relativistic
analysis, to an insightful resolution of all paradoxes implied by quantum
nonlocality.Comment: arXiv admin note: text overlap with arXiv:1203.003
Elements of F-ast Proton Decay
Gauge coupling unification in the Minimal Supersymmetric Standard Model
(MSSM) strongly suggests the existence of a Grand Unified Theory (GUT), which
could be probed by the observation of proton decay. Proton lifetime in the p
\to (e+|mu+) pi0 dimension six mode is proportional in the fourth power to the
GUT mass scale, and inversely proportional in the fourth power to the GUT
coupling. We provide an updated dictionary of solutions for the relevant
unification parameters with generic beta-function coefficients, significantly
upgrading the level of detail with which second order effects are treated, and
correcting subtle published errors. F-lipped SU(5) with strict MSSM field
content is known to survive existing null detection limits for proton decay
approaching 10^34 years, and indeed, the lifetime predicted by prior studies
can be so long that successful detection is not currently plausible. Recently
studied classes of F-theory derived GUT models postulate additional vector-like
multiplets at the TeV scale which modify the renormalization group to yield a
substantial increase in the SU(3)_C X SU(2)_L unified coupling. We find the
conjunction of these models with the F-resh analysis employed to be
comparatively F-ast proton decay, only narrowly evading existing detection
limits, and likely falling within the observable range of proposed next
generation detectors such as DUSEL and Hyper-Kamiokande. The TeV-scale vector
multiplets are themselves suitable for cross correlation by the Large Hadron
Collider. Their presence moreover magnifies the gap between the dual mass
scales of Flipped SU(5), allowing for an elongated second stage
renormalization, pushing grand unification to the doorstep of the reduced
Planck mass.Comment: V2, As published in Nuclear Physics B; 57 pages, 7 figures, 12 table
Ultra-high energy cosmic ray investigations by means of EAS muon density measurements
A new approach to investigations of ultra-high energy cosmic rays based on
the ground-level measurements of the spectra of local density of EAS muons at
various zenith angles is considered. Basic features of the local muon density
phenomenology are illustrated using a simple semi-analytical model. It is shown
that muon density spectra are sensitive to the spectrum slope, primary
composition, and to the features of hadronic interaction. New experimental data
on muon bundles at zenith angles from 30 degrees to horizon obtained with the
coordinate detector DECOR are compared with CORSIKA-based simulations. It is
found that measurements of muon density spectra in inclined EAS give
possibility to study characteristics of primary cosmic ray flux in a very wide
energy range from 10^15 to 10^19 eV.Comment: 7 pages, 7 figures. Presented at CRIS-2006, Catania, Italy, May 29 -
June 2, 2006. Accepted for publication in Nucl. Phys. B (Proc. Suppl.
Discontinuities in the Electromagnetic Fields of Vortex Beams in the Complex Source/Sink Model
An analytical discontinuity is reported in what was thought to be the
discontinuity-free exact nonparaxial vortex beam phasor obtained within the
complex source/sink model. This discontinuity appears for all odd values of the
orbital angular momentum mode. Such discontinuities in the phasor lead to
nonphysical discontinuities in the real electromagnetic field components. We
identify the source of the discontinuities, and provide graphical evidence of
the discontinuous real electric fields for the first and third orbital angular
momentum modes. A simple means of avoiding these discontinuities is presented.Comment: 10 pages, 4 figure
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