6,863 research outputs found

### Physical state representations and gauge fixing in string theory

We re-examine physical state representations in the covariant quantization of
bosonic string. We especially consider one parameter family of gauge fixing
conditions for the residual gauge symmetry due to null states (or BRST exact
states), and obtain explicit representations of observable Hilbert space which
include those of the DDF states. This analysis is aimed at giving a necessary
ingredient for the complete gauge fixing procedures of covariant string field
theory such as temporal or light-cone gauge.Comment: 16 page

### Prompt GeV-TeV Emission of Gamma-Ray Bursts Due to High-Energy Protons, Muons and Electron-Positron Pairs

In the framework of the internal shock scenario, we model the broadband
prompt emission of gamma-ray bursts (GRBs) with emphasis on the GeV-TeV bands,
utilizing Monte Carlo simulations that include various processes associated
with electrons and protons accelerated to high energies. While inverse Compton
emission from primary electrons is often dominant, different proton-induced
mechanisms can also give rise to distinct high-energy components, such as
synchrotron emission from protons, muons or secondary electrons/positrons
injected via photomeson interactions. In some cases, they give rise to double
spectral breaks that can serve as unique signatures of ultra-high-energy
protons. We discuss the conditions favorable for such emission, and how they
are related to the production of ultra-high-energy cosmic rays and neutrinos in
internal shocks. Ongoing and upcoming observations by {\it GLAST}, atmospheric
Cerenkov telescopes and other facilities will test these expectations and
provide important information on the physical conditions in GRB outflows.Comment: 11 pages, 8 figures and 14 appendix figures, accepted for publication
in ApJ vol. 671 with minor revision

### Observability of surface Andreev bound states in a topological insulator in proximity to an s-wave superconductor

To guide experimental work on the search for Majorana zero-energy modes, we
calculate the superconducting pairing symmetry of a three-dimensional
topological insulator in combination with an s-wave superconductor. In analogy
to the case of nanowires with strong spin-orbit coupling we show how the
pairing symmetry changes across different topological regimes. We demonstrate
that a dominant p-wave pairing relation is not sufficient to realize a Majorana
zero-energy mode useful for quantum computation. Our main result of this paper
is the relation between odd-frequency pairing and Majorana zero energy modes by
using Green functions techniques in three-dimensional topological insulators in
the so-called Majorana regime. We discuss thereafter how the pairing relations
in the different regimes can be observed in the shape of the tunneling
conductance of an s-wave proximized three-dimensional topological insulator. We
will discuss the necessity to incorporate a ferromagnetic insulator to localize
the zero-energy bound state to the interface as a Majorana mode.Comment: Accepted for publication in Journal of Physics: Condensed Matte

### Level Truncated Tachyon Potential in Various Gauges

New gauge fixing condition with single gauge parameter proposed by the
authors is applied to the level truncated analysis of tachyon condensation in
cubic open string field theory. It is found that the only one real non-trivial
extremum persists to appear in the well-defined region of the gauge parameter,
while the other solutions are turned out to be gauge-artifacts. Contrary to the
previously known pathology in the Feynman-Siegel gauge, tachyon potential is
remarkably smooth enough around Landau-type gauge.Comment: 13 pages, 5 figures. For associated movie files, see
http://hep1.c.u-tokyo.ac.jp/~kato/sft

### Scattering by randomly oriented ellipsoids: Application to aerosol and cloud problems

A program was developed for computing the scattering and absorption by arbitrarily oriented and randomly oriented prolate and oblate spheroids. This permits examination of the effect of particle shape for cases ranging from needles through spheres to platelets. Applications of this capability to aerosol and cloud problems are discussed. Initial results suggest that the effect of nonspherical particle shape on transfer of radiation through aerosol layers and cirrus clouds, as required for many climate studies, can be readily accounted for by defining an appropriate effective spherical particle radius

### Tenth-order lepton g-2: Contribution from diagrams containing a sixth-order light-by-light-scattering subdiagram internally

This paper reports the result of our evaluation of the tenth-order QED
correction to the lepton g-2 from Feynman diagrams which have sixth-order
light-by-light-scattering subdiagrams, none of whose vertices couple to the
external magnetic field. The gauge-invariant set of these diagrams, called Set
II(e), consists of 180 vertex diagrams. In the case of the electron g-2 (a_e),
where the light-by-light subdiagram consists of the electron loop, the
contribution to a_e is found to be - 1.344 9 (10) (\alpha /\pi)^5. The
contribution of the muon loop to a_e is - 0.000 465 (4) (\alpha /\pi)^5. The
contribution of the tau-lepton loop is about two orders of magnitudes smaller
than that of the muon loop and hence negligible. The sum of all of these
contributions to a_e is - 1.345 (1) (\alpha /\pi)^5. We have also evaluated the
contribution of Set II(e) to the muon g-2 (a_\mu). The contribution to a_\mu
from the electron loop is 3.265 (12) (\alpha /\pi)^5, while the contribution of
the tau-lepton loop is -0.038 06 (13) (\alpha /\pi)^5. The total contribution
to a_\mu, which is the sum of these two contributions and the mass-independent
part of a_e, is 1.882 (13) (\alpha /\pi)^5.Comment: 18 pages, 3 figures, REVTeX4, axodraw.sty used, changed title,
corrected uncertainty of a_mu, added a referenc

### Quantum theory as a relevant framework for the statement of probabilistic and many-valued logic

Based on ideas of quantum theory of open systems we propose the consistent
approach to the formulation of logic of plausible propositions. To this end we
associate with every plausible proposition diagonal matrix of its likelihood
and examine it as density matrix of relevant quantum system. We are showing
that all logical connectives between plausible propositions can be represented
as special positive valued transformations of these matrices. We demonstrate
also the above transformations can be realized in relevant composite quantum
systems by quantum engineering methods. The approach proposed allows one not
only to reproduce and generalize results of well-known logical systems
(Boolean, Lukasiewicz and so on) but also to classify and analyze from unified
point of view various actual problems in psychophysics and social sciences.Comment: 7 page

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