4,721 research outputs found
Surface Effects of Flame Spreading over Igniting Composite Solid Propellants Constituents
Flame spreading over surface of igniting composite solid propellant constituent
Regularization of identity based solution in string field theory
We demonstrate that an Erler-Schnabl type solution in cubic string field
theory can be naturally interpreted as a gauge invariant regularization of an
identity based solution. We consider a solution which interpolates between an
identity based solution and ordinary Erler-Schnabl one. Two gauge invariant
quantities, the classical action and the closed string tadpole, are evaluated
for finite value of the gauge parameter. It is explicitly checked that both of
them are independent of the gauge parameter.Comment: 9 pages, minor typos corrected and references adde
Realistic Neutrino Opacities for Supernova Simulations With Correlations and Weak Magnetism
Advances in neutrino transport allow realistic neutrino interactions to be
incorporated into supernova simulations. We add tensor couplings to
relativistic RPA calculations of neutrino opacities. Our results reproduce
free-space neutrino-nucleon cross sections at low density, including weak
magnetism and recoil corrections. In addition, our opacities are
thermodynamically consistent with relativistic mean field equations of state.
We find antineutrino mean free paths that are considerably larger then those
for neutrinos. This difference depends little on density. In a supernova, this
difference could lead to an average energy of that is larger than
that for by an amount that is comparable to the energy difference
between and Comment: 15 pages, 10 figures, submitted to PRC, minor changes to figs. (9,10
Quenching and Tomography from RHIC to LHC
We compare fully perturbative and fully nonperturbative pictures of high-pT
energy loss calculations to the first results from LHC. While over-suppressed
compared to published ALICE data, parameter-free pQCD predictions based on the
WHDG energy loss model constrained to RHIC data simultaneously describe well
the preliminary CMS hadron suppression, ATLAS charged hadron v2, and ALICE D
meson suppression; we also provide for future reference WHDG predictions for B
meson RAA. However, energy loss calculations based on AdS/CFT also
qualitatively describe well the RHIC pion and non-photonic electron suppression
and LHC charged hadron suppression. We propose the double ratio of charm to
bottom quark RAA will qualitatively distinguish between these two energy loss
pictures.Comment: 4 pages, 3 figures. Proceedings for Quark Matter 201
Greybody factor for the BTZ black hole and a 5D black hole
We study the 5D black holes in the type IIB superstring theory compactified
on . Far from horizon, we have flat space-time. Near horizon,
we have . We calculate the
greybody factor of a minimally coupled scalar by replacing the original
geometry() by . In the
low-energy scattering, it turns out that the result agrees with the greybody
factor of the 5D black hole (or D1 + D5 branes)in the dilute gas approximation.
This confirms that the -theory() contains the
essential information about the bulk 5D black holes.Comment: some discussions are added, 15 Pages, No figure, RevTe
Relativistic analysis of the 208Pb(e,e'p)207Tl reaction at high momentum
The recent 208Pb(e,e'p)207Tl data from NIKHEF-K at high missing momentum
(p_m>300 MeV/c) are compared to theoretical results obtained with a fully
relativistic formalism previously applied to analyze data on the low missing
momentum (p_m < 300 MeV/c) region. The same relativistic optical potential and
mean field wave functions are used in the two p_m-regions. The spectroscopic
factors of the various shells are extracted from the analysis of the low-p_m
data and then used in the high-p_m region. In contrast to previous analyses
using a nonrelativistic mean field formalism, we do not find a substantial
deviation from the mean field predictions other than that of the spectroscopic
factors, which appear to be consistent with both low- and high-p_m data. We
find that the difference between results of relativistic and nonrelativistic
formalisms is enhanced in the p_m<0 region that will be interesting to explore
experimentally.Comment: 12 pages, LaTeX+Revtex, included 3 postscript figures. To appear in
the Physical Review C (Rapid Communications
Hamiltonian Derivations of the Generalized Jarzynski Equalities under Feedback Control
In the presence of feedback control by "Maxwell's demon," the second law of
thermodynamics and the nonequilibrium equalities such as the Jarzynski equality
need to be generalized. In this paper, we derive the generalized Jarzynski
equalities for classical Hamiltonian dynamics based on the Liouville's theorem,
which is the same approach as the original proof of the Jarzynski equality
[Phys. Rev. Lett. 78, 2690 (1997)]. The obtained equalities lead to the
generalizations of the second law of thermodynamics for the Hamiltonian systems
in the presence of feedback control.Comment: Proceedings of "STATPHYS - Kolkata VII", November 26-30, 2010,
Kolkata, Indi
Nuclear medium modifications of the NN interaction via quasielastic () and () scattering
Within the relativistic PWIA, spin observables have been recalculated for
quasielastic () and () reactions on a Ca
target. The incident proton energy ranges from 135 to 300 MeV while the
transferred momentum is kept fixed at 1.97 fm^{-1}. In the present
calculations, new Horowitz-Love--Franey relativistic NN amplitudes have been
generated in order to yield improved and more quantitative spin observable
values than before. The sensitivities of the various spin observables to the NN
interaction parameters, such as (1) the presence of the surrounding nuclear
medium, (2) a pseudoscalar versus a pseudovector interaction term, and (3)
exchange effects, point to spin observables which should preferably be measured
at certain laboratory proton energies, in order to test current nuclear models.
This study also shows that nuclear medium effects become more important at
lower proton energies ( 200 MeV). A comparison to the limited available
data indicates that the relativistic parametrization of the NN scattering
amplitudes in terms of only the five Fermi invariants (the SVPAT form) is
questionable.Comment: 10 pages, 6 Postscript figures, uses psfig.sty and article.sty,
submitted to Phys. Rev.
Fate of the Black String Instability
Gregory and Laflamme showed that certain nonextremal black strings (and
p-branes) are unstable to linearized perturbations. It is widely believed that
this instability will cause the black string horizon to classically pinch off
and then quantum mechanically separate, resulting in higher dimensional black
holes. We argue that this cannot happen. Under very mild assumptions, classical
event horizons cannot pinch off. Instead, they settle down to new static black
string solutions which are not translationally invariant along the string.Comment: 11 pages, v2: few clarifications and references adde
Comment on Counting Black Hole Microstates Using String Dualities
We discuss a previous attempt at a microscopic counting of the entropy of
asymptotically flat non-extremal black-holes. This method used string dualities
to relate 4 and 5 dimensional black holes to the BTZ black hole. We show how
the dualities can be justified in a certain limit, equivalent to a near horizon
limit, but the resulting spacetime is no longer asymptotically flat.Comment: 10 pages, harvmac. v(2) typo correcte
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