Casimir-Polder forces in the presence of the cosmic photon heat bath

We study the effect of a photon background at finite temperature $T$ on the Van der Waals interactions among neutral bodies. It turns out that the long-range Casimir-Polder force is unaffected for distances much less than $T^{-1}$ and strongly enhanced for distances much above $T^{-1}$.Comment: 8 pages, 2 figure

Where is the Information Stored in Black Holes?

It is shown that many modes of the gravitational field exist only inside the horizon of an extreme black hole in string theory. At least in certain cases, the number of such modes is sufficient to account for the Bekenstein-Hawking entropy. These modes are associated with sources which carry Ramond-Ramond charge, and so may be viewed as the strong coupling limit of D-branes. Although these sources naturally live at the singularity, they are well defined and generate modes which extend out to the horizon. This suggests that the information in an extreme black hole is not localized near the singularity or the horizon, but extends between them.Comment: 21 pages, reference corrected and comment adde

Statistical Effects and the Black Hole/D-brane Correspondence

The horizon area and curvature of three-charge BPS black strings are studied in the D-brane ensemble for the stationary black string. The charge distributions along the string are used to translate the classical expressions for the horizon area and curvature of BPS black strings with waves into operators on the D-brane Hilbert space. Despite the fact that any `wavy' black string has smaller horizon area and divergent curvature, the typical values of the horizon area and effects of the horizon curvature in the D-brane ensemble deviate negligibly from those of the original stationary black string in the limit of large integer charges. Whether this holds in general will depend on certain properties of the quantum bound states.Comment: 13 pages, RevTex, small errors corrected, some interpretation changed in light of new result

Relativistic nuclear structure effects in quasielastic neutrino scattering

Charged-current cross sections are calculated for quasielastic neutrino and antineutrino scattering using a relativistic meson-nucleon model. We examine how nuclear-structure effects, such as relativistic random-phase-approximation (RPA) corrections and momentum-dependent nucleon self-energies, influence the extraction of the axial form factor of the nucleon. RPA corrections are important only at low-momentum transfers. In contrast, the momentum dependence of the relativistic self-energies changes appreciably the value of the axial-mass parameter, $M_A$, extracted from dipole fits to the axial form factor. Using Brookhaven's experimental neutrino spectrum we estimate the sensitivity of M$_A$ to various relativistic nuclear-structure effects.Comment: 26 pages, revtex, 6 postscript figures (available upon request

The Vector Analyzing Power in Elastic Electron-Nucleus Scattering

The vector analyzing power A_n is calculated for elastic electron scattering from a variety of spin zero nuclei at energies from 14 MeV to 3 GeV. Time reversal symmetry insures that A_n vanish in first Born approximation. Therefore A_n depends on Coulomb distortions and can be large for scattering from heavy nuclei. The vector analyzing power is a potential source of systematic error for parity violation experiments. We find that A_n=-0.361 ppm for the kinematics of the Parity Radius Experiment (PREX) involving 850 MeV electrons scattering at six degrees from 208Pb. This is comparable to the parity violating asymmetry. However for HAPPEX He involving 3 GeV electrons scattering on 4He we find that A_n is very small.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

Long range forces induced by neutrinos at finite temperature

We revisit and extend previous work on neutrino mediated long range forces in a backround at finite temperature. For Dirac neutrinos, we correct existing results. We also give new results concerning spin-dependent as well as spin-independent long range forces associated to Majorana neutrinos. An interesting outcome of the investigation is that, for both types of neutrinos whether massless or not, the effect of the relic neutrino heat bath is to convert those forces into attractive ones in the supra-millimeter scale while they stay repulsive within the sub-millimeter scale.Comment: 8 pages, Latex, 1 figur

Surface Effects of Flame Spreading over Igniting Composite Solid Propellants Constituents

Flame spreading over surface of igniting composite solid propellant constituent

Relativistic predictions of spin observables for exclusive proton knockout reactions

Within the framework of the relativistic distorted wave impulse approximation (DWIA), we investigate the sensitivity of complete sets of polarization transfer observables for exclusive proton knockout from the 3s$_{1/2}$, 2d$_{3/2}$ and 2d$_{5/2}$ states in $^{208}$Pb, at an incident laboratory kinetic energy of 202 MeV, and for coincident coplanar scattering angles ($28.0^{\circ}$, $-54.6^{\circ}$), to different distorting optical potentials, finite-range (FR) versus zero-range (ZR) approximations to the DWIA, as well as medium-modified meson-nucleon coupling constants and meson masses. Results are also compared to the nonrelativistic DWIA predictions based on the Schr\"{o}dinger equation.Comment: Submitted for publication to Physicical Review C, 23 pages, 7 figure