1,054 research outputs found
Absolutely anticommuting (anti-)BRST symmetry transformations for topologically massive Abelian gauge theory
We demonstrate the existence of the nilpotent and absolutely anticommuting
Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations for the
four (3 + 1)-dimensional (4D) topologically massive Abelian U(1) gauge theory
that is described by the coupled Lagrangian densities (which incorporate the
celebrated (B \wedge F) term). The absolute anticommutativity of the (anti-)
BRST symmetry transformations is ensured by the existence of a Curci-Ferrari
type restriction that emerges from the superfield formalism as well as from the
equations of motion that are derived from the above coupled Lagrangian
densities. We show the invariance of the action from the point of view of the
symmetry considerations as well as superfield formulation. We discuss,
furthermore, the topological term within the framework of superfield formalism
and provide the geometrical meaning of its invariance under the (anti-) BRST
symmetry transformations.Comment: LaTeX file, 22 pages, journal versio
Universal light quark mass dependence and heavy-light meson spectroscopy
Clean predictions are presented for all the spin-averaged heavy-light meson
spectroscopies. A new symmetry is identified wherein the energy eigenstates
have a universal dependence on both the light and heavy quark masses. This
universality is used in an efficient analysis of these mesons within the QCD
string/flux tube picture. Unique predictions for all the D, D_s, B, and B_s
type mesons in terms of just four measured quantities.Comment: REVTeX4, 6 pages, 9 eps figure
One Loop Vaccum Polarization in a Locally de Sitter Background
We compute the one loop vacuum polarization from massless, minimally coupled
scalar QED in a locally de Sitter background. Gauge invariance is maintained
through the use of dimensional regularization, whereas conformal invariance is
explicitly broken by the scalar kinetic term as well as through the conformal
anomaly. A fully renormalized result is obtained. The one loop corrections to
the linearized, effective field equations do not vanish when evaluated
on-shell. In fact the on-shell one loop correction depends quadratically on the
inflationary scale factor, similar to a photon mass. The contribution from the
conformal anomaly is insignificant by comparison.Comment: 31 pages, LaTeX 2 epsilon, 4 figure
Dimensionally Regulated Graviton 1-Point Function in de Sitter
We use dimensional regularization to compute the 1PI 1-point function of
quantum gravity at one loop order in a locally de Sitter background. As with
other computations, the result is a finite constant at this order. It
corresponds to a small positive renormalization of the cosmological constant.Comment: 25 pages, LaTeX 2epsilon, uses Axodraw for one figure, revised to add
some reference
Steam Generator Group Project. Task 6. Channel head decontamination
The Steam Generator Group Project utilizes a retired-from-service pressurized-water-reactor steam generator as a test bed and source of specimens for research. An important preparatory step to primary side research activities was reduction of the radiation field in the steam generator channel head. This task report describes the channel head decontamination activities. Though not a programmatic research objective it was judged beneficial to explore the use of dilute reagent chemical decontamination techniques. These techniques presented potential for reduced personnel exposure and reduced secondary radwaste generation, over currently used abrasive blasting techniques. Two techniques with extensive laboratory research and vendors prepared to offer commercial application were tested, one on either side of the channel head. As indicated in the report, both techniques accomplished similar decontamination objectives. Neither technique damaged the generator channel head or tubing materials, as applied. This report provides details of the decontamination operations. Application system and operating conditions are described
Looking back at superfluid helium
A few years after the discovery of Bose Einstein condensation in several
gases, it is interesting to look back at some properties of superfluid helium.
After a short historical review, I comment shortly on boiling and evaporation,
then on the role of rotons and vortices in the existence of a critical velocity
in superfluid helium. I finally discuss the existence of a condensate in a
liquid with strong interactions, and the pressure variation of its superfluid
transition temperature.Comment: Conference "Bose Einstein Condensation", Institut henri Poincare,
Paris, 29 march 200
BRST analysis of topologically massive gauge theory: novel observations
A dynamical non-Abelian 2-form gauge theory (with B \wedge F term) is endowed
with the "scalar" and "vector" gauge symmetry transformations. In our present
endeavor, we exploit the latter gauge symmetry transformations and perform the
Becchi-Rouet-Stora-Tyutin (BRST) analysis of the four (3 + 1)-dimensional (4D)
topologically massive non-Abelian 2-form gauge theory. We demonstrate the
existence of some novel features that have, hitherto, not been observed in the
context of BRST approach to 4D (non-)Abelian 1-form as well as Abelian 2-form
and 3-form gauge theories. We comment on the differences between the novel
features that emerge in the BRST analysis of the "scalar" and "vector" gauge
symmetries of the theory.Comment: LaTeX file, 14 pages, an appendix added, references expanded, version
to appear in EPJ
Vibrational properties of amorphous silicon from tight-binding O(N) calculation
We present an O(N) algorithm to study the vibrational properties of amorphous
silicon within the framework of tight-binding approach. The dynamical matrix
elements have been evaluated numerically in the harmonic approximation
exploiting the short-range nature of the density matrix to calculate the
vibrational density of states which is then compared with the same obtained
from a standard O() algorithm. For the purpose of illustration, an
1000-atom model is studied to calculate the localization properties of the
vibrational eigenstates using the participation numbers calculation.Comment: 5 pages including 5 ps figures; added a figure and a few references;
accepted in Phys. Rev.
Volume element structure and roton-maxon-phonon excitations in superfluid helium beyond the Gross-Pitaevskii approximation
We propose a theory which deals with the structure and interactions of volume
elements in liquid helium II. The approach consists of two nested models linked
via parametric space. The short-wavelength part describes the interior
structure of the fluid element using a non-perturbative approach based on the
logarithmic wave equation; it suggests the Gaussian-like behaviour of the
element's interior density and interparticle interaction potential. The
long-wavelength part is the quantum many-body theory of such elements which
deals with their dynamics and interactions. Our approach leads to a unified
description of the phonon, maxon and roton excitations, and has noteworthy
agreement with experiment: with one essential parameter to fit we reproduce at
high accuracy not only the roton minimum but also the neighboring local maximum
as well as the sound velocity and structure factor.Comment: 9 pages, 6 figure
Reversed anisotropies and thermal contraction of FCC (110) surfaces
The observed anisotropies of surface vibrations for unreconstructed FCC metal
(110) surfaces are often reversed from the "common sense" expectation. The
source of these reversals is investigated by performing ab initio density
functional theory calculations to obtain the surface force constant tensors for
Ag(110), Cu(110) and Al(110). The most striking result is a large enhancement
in the coupling between the first and third layers of the relaxed surface,
which strongly reduces the amplitude of out-of-plane vibrations of atoms in the
first layer. This also provides a simple explanation for the thermal
contraction of interlayer distances. Both the anisotropies and the thermal
contraction arise primarily as a result of the bond topology, with all three
(110) surfaces showing similar behavior.Comment: 13 pages, in revtex format, plus 1 postscript figur
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