587 research outputs found
Characteristics of Cosmic Time
The nature of cosmic time is illuminated using Hamilton-Jacobi theory for
general relativity. For problems of interest to cosmology, one may solve for
the phase of the wavefunctional by using a line integral in superspace. Each
contour of integration corresponds to a particular choice of time hypersurface,
and each yields the same answer. In this way, one can construct a covariant
formalism where all time hypersurfaces are treated on an equal footing. Using
the method of characteristics, explicit solutions for an inflationary epoch
with several scalar fields are given. The theoretical predictions of double
inflation are compared with recent galaxy data and large angle microwave
background anisotropies.Comment: 20 pages, RevTex using Latex 2.09, Submitted to Physical Review D Two
figures included in fil
Determination of HQET parameter \lambda_1 from Inclusive Semileptonic B Meson Decay Spectrum
We estimate the heavy quark effective theory parameter \lambda_1 from
inclusive semileptonic B-meson decay spectrum. By using recent CLEO double
lepton tagging data of B -> X e nu, which shows the lepton momentum as low as
0.6 GeV, we extracted \lambda_1 \sim -0.58 GeV^2. We also derived \bar\Lambda
\sim 0.46 GeV and |V_{cb}| = 0.041 \pm 0.002.Comment: 13 pages, 3 figures, LaTeX. Typos are corrected, and added one
commen
Particle dynamics in a class of 2-dimensional gravity theories
We provide a method to determine the motion of a classical massive particle
in a background geometry of 2-dimensional gravity theories, for which the
Birkhoff theorem holds. In particular, we get the particle trajectory in a
continuous class of 2-dimensional dilaton gravity theories that includes the
Callan-Giddings-Harvey-Strominger (CGHS) model, the Jackiw-Teitelboim (JT)
model, and the -dimensional -wave Einstein gravity. The explicit
trajectory expressions for these theories are given along with the discussions
on the results.Comment: 15 pages, LaTeX. The deletion of the repeated portion of the abstract
and the proper line wrapping of the tex file. No other change
Conductivity Due to Classical Phase Fluctuations in a Model For High-T_c Superconductors
We consider the real part of the conductivity, \sigma_1(\omega), arising from
classical phase fluctuations in a model for high-T_c superconductors. We show
that the frequency integral of that conductivity, \int_0^\infty \sigma_1
d\omega, is non-zero below the superconducting transition temperature ,
provided there is some quenched disorder in the system. Furthermore, for a
fixed amount of quenched disorder, this integral at low temperatures is
proportional to the zero-temperature superfluid density, in agreement with
experiment. We calculate \sigma_1(\omega) explicitly for a model of overdamped
phase fluctuations.Comment: 4pages, 2figures, submitted to Phys.Rev.
Inflationary models inducing non-Gaussian metric fluctuations
We construct explicit models of multi-field inflation in which the primordial
metric fluctuations do not necessarily obey Gaussian statistics. These models
are realizations of mechanisms in which non-Gaussianity is first generated by a
light scalar field and then transferred into curvature fluctuations. The
probability distribution functions of the metric perturbation at the end of
inflation are computed. This provides a guideline for designing strategies to
search for non-Gaussian signals in future CMB and large scale structure
surveys.Comment: 4 pages, 7 figure
Linear optical implementation of a single mode quantum filter and generation of multi-photon polarization entangled state
We propose a scheme to implement a single-mode quantum filter, which
selectively eliminates the one-photon state in a quantum state
. The vacuum state and the two photon state are
transmitted without any change. This scheme requires single-photon sources,
linear optical elements and photon detectors. Furthermore we demonstrate, how
this filter can be used to realize a two-qubit projective measurement and to
generate multi-photon polarization entangled states.Comment: revision submitted to PR
Decay Constants and Semileptonic Decays of Heavy Mesons in Relativistic Quark Model
We investigate the and mesons in the relativistic quark model by
applying the variational method with the Gaussian wave function. We calculate
the Fermi momentum parameter , and obtain
GeV, which is almost independent of the input parameters, , ,
and . We then calculate the ratio /, and obtain the
result which is larger, by the factor of about 1.3, than
given by the naive nonrelativistic analogy. This result is in a good agreement
with the recent Lattice calculations. We also calculate the ratio
/. In these calculations the wave function at
origin is essential. We also determine by comparing the
theoretical prediction of the ACCMM model with the lepton energy spectrum of from the recent ARGUS analysis, and find that
GeV, when we use GeV. However, this
experimentally determined value of is strongly dependent on the value
of input parameter .Comment: 15 pages (Latex) (uses epsfig.sty, 1 figure appended as a uuencoded
compressed ps-file
Abelian 2-form gauge theory: superfield formalism
We derive the off-shell nilpotent Becchi-Rouet-Stora-Tyutin (BRST) and
anti-BRST symmetry transformations for {\it all} the fields of a free Abelian
2-form gauge theory by exploiting the geometrical superfield approach to BRST
formalism. The above four (3 + 1)-dimensional (4D) theory is considered on a
(4, 2)-dimensional supermanifold parameterized by the four even spacetime
variables x^\mu (with \mu = 0, 1, 2, 3) and a pair of odd Grassmannian
variables \theta and \bar\theta (with \theta^2 = \bar\theta^2 = 0, \theta
\bar\theta + \bar\theta \theta = 0). One of the salient features of our present
investigation is that the above nilpotent (anti-)BRST symmetry transformations
turn out to be absolutely anticommuting due to the presence of a Curci-Ferrari
(CF) type of restriction. The latter condition emerges due to the application
of our present superfield formalism. The actual CF condition, as is well-known,
is the hallmark of a 4D non-Abelian 1-form gauge theory. We demonstrate that
our present 4D Abelian 2-form gauge theory imbibes some of the key signatures
of the 4D non-Abelian 1-form gauge theory. We briefly comment on the
generalization of our supperfield approach to the case of Abelian 3-form gauge
theory in four (3 + 1)-dimensions of spacetime.Comment: LaTeX file, 23 pages, journal versio
Correlation induced phonon softening in low density coupled bilayer systems
We predict a possible phonon softening instability in strongly correlated
coupled semiconductor bilayer systems. By studying the plasmon-phonon coupling
in coupled bilayer structures, we find that the renormalized acoustic phonon
frequency may be softened at a finite wave vector due to many-body local field
corrections, particularly in low density systems where correlation effects are
strong. We discuss experimental possibilities to search for this predicted
phonon softening phenomenon.Comment: 4 pages with 2 figure
A fitter code for Deep Virtual Compton Scattering and Generalized Parton Distributions
We have developped a fitting code based on the leading-twist handbag Deep
Virtual Compton Scattering (DVCS) amplitude in order to extract the Generalized
Parton Distributions (GPD) information from DVCS observables in the valence
region. In a first stage, with simulations and pseudo-data, we show that the
full GPD information can be recovered from experimental data if enough
observables are measured. If only part of these observables are measured,
valuable information can still be extracted, certain observables being
particularly sensitive to certain GPDs. In a second stage, we make a practical
application of this code to the recent DVCS Jefferson Lab Hall A data from
which we can extract numerical constraints for the two GPD Compton Form
Factors.Comment: 15 pages, 8 figure
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