28526248
New exact solutions for the purely cubic bosonic string field theory.
A procedure is described for obtaining new exact solutions for the purely cubic form of Witten's bosonic string field theory. These solutions do not correspond to conformally invariant $\ensuremath{\sigma}$ models. Some of them have no tachyons in their spectrum of linearized fluctuations (but may have negative-norm states). Others make no reference to a space-time metric.
15074147
Photoemission “experiments” on holographic superconductors
We study the effects of a superconducting condensate on holographic Fermi surfaces. With a suitable coupling between the fermion and the condensate, there are stable quasiparticles with a gap. We find some similarities with the phenomenology of the cuprates: in systems whose normal state is a non-Fermi liquid with no stable quasiparticles, a stable quasiparticle peak appears in the condensed phase.
14670933
Microstates of a neutral black hole in M theory.
We consider vacuum solutions in M theory of the form of a five-dimensional Kaluza-Klein black hole cross T6. In a certain limit, these include the five-dimensional neutral rotating black hole (cross T6). From a type-IIA standpoint, these solutions carry D0 and D6 charges. We show that there is a simple D-brane description which precisely reproduces the Hawking-Bekenstein entropy in the extremal limit, even though supersymmetry is completely broken.
15786164
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.
7270273
Pair creation of extremal black holes and Kaluza-Klein monopoles.
Classical solutions describing charged dilaton black holes accelerating in a background magnetic field have recently been found. They include the Ernst metric of the Einstein-Maxwell theory as a special case. We study the extremal limit of these solutions in detail, both at the classical and quantum levels. It is shown that near the event horizon the extremal solutions reduce precisely to the static extremal black hole solutions. For a particular value of the dilaton coupling, these extremal black holes are five-dimensional Kaluza-Klein monopoles. The Euclidean sections of these solutions can be interpreted as instantons describing the pair creation of extremal black holes and/or Kaluza-Klein monopoles in a magnetic field. The action of these instantons is calculated and found to agree with the Schwinger result in the weak-field limit. For the Euclidean Ernst solution, the action for the extremal solution differs from that of the previously discussed wormhole instanton by the Bekenstein-Hawking entropy. However, in many cases quantum corrections become large in the vicinity of the black hole, and the precise description of the creation process is unknown.
23955919
Origin of gauge invariance in string theory.
We present a first quantization of the space-time embedding X/sup ..mu../ and the world-sheet metric rho of the open bosonic string. The world-sheet metric rho decouples from S-matrix elements in 26 dimensions. This formulation of the theory naturally includes 26-dimensional gauge transformations. The gauge invariance of S-matrix elements is a direct consequence of the decoupling of rho. Second quantization leads to a string field Phichemically bondX/sup ..mu../,rhochemically bond with a gauge-covariant equation of motion.
38611028
Density dependence of nuclear neutrino-pair production.
Nuclear decay via neutrino-pair production is found to have a large density dependence because of intermediate electromagnetic couplings to electrons. These are calculated in a relativistic random phase approximation. The decay rate for vector (Fermi) transitions producing electron type neutrino pairs can be enhanced by 10{sup 5} or more at densities relevant for stellar collapse. Axial-vector (Gamow-Teller) transitions are not enhanced.
15842686
Relativistic and nuclear structure effects in parity-violating quasielastic electron scattering.
The parity-violating longitudinal asymmetry [ital scrA] is calculated for quasielastic electron scattering. We use a varietry of relativistic mean field models for the response of nuclear matter and [sup 12]C at a momentum transfer of [ital q]=550 MeV/[ital c]. Relativistic effects from a reduced nucleon mass, RPA correlations, and vacuum polarization can all change [ital scrA] by a relatively large amount. These large nuclear structure corrections could make it impossible to extract strange quark matrix elements or radiative corrections to weak axial currents.
15357267
Delta excitations in neutrino-nucleus scattering.
We derive the contribution of {Delta}-{ital h} excitations to quasielastic charged-current neutrino-nucleus scattering in the framework of relativistic mean-field theory. We discuss the effect of {Delta} production on the determination of the axial mass {ital M}{sub {ital A}} in neutrino scattering experiments. {copyright} {ital 1996 The American Physical Society.}
31199813
Neutrino-nucleus quasifree neutral current reactions and the nucleon strange quark content.
Differential cross sections for neutrino- (and antineutrino-) induced nucleon knockout are calculated for neutral-current reactions from nuclei. A relativistic Fermi gas model with binding energy corrections is used. We examine the accuracy with which strange quark axial and vector current parameters can be extracted from both existing and (possible) future experiments. Both high (above 1 GeV) and low (near 150 MeV) neutrino energies and the knockout of neutrons and protons are considered.
37677102
Microscopic relativistic description of proton-nucleus scattering.
Microscopic relativistic optical potentials have been calculated for closed shell nuclei at energies near 200 MeV. These calculations go beyond the simple RIA by resolving ambiguities in the relativistic NN amplitudes and including Pauli blocking corrections.