Charged black holes in string theory.
A family of solutions to low-energy string theory representing static, spherically symmetric charged black holes is described. They are labeled by their mass, charge, and asymptotic value of the scalar dilaton. The presence of the dilaton is found to have important consequences. In particular, the extremal charged black holes'' are found to be geodesically complete spacetimes with no event horizons and no singularities. Implications of these new solutions for black-hole thermodynamics and open questions in general relativity are also discussed.

title: Photoemission “experiments” on holographic superconductors
abstract: 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.

title: Pair creation of extremal black holes and Kaluza-Klein monopoles.
abstract: 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.

title: Origin of gauge invariance in string theory.
abstract: 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.

title: Where is the information stored in black holes
abstract: 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.

title: Microstates of a neutral black hole in M theory.
abstract: 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.

title: Relativistic nuclear structure effects in quasielastic neutrino scattering.
abstract: 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 {ital M}{sub {ital A}} extracted from dipole fits to the axial form factor. Using Brookhaven`s experimental neutrino spectrum we estimate the sensitivity of {ital M}{sub {ital A}} to various relativistic nuclear-structure effects.

title: Cold nuclear fusion in metallic hydrogen and normal metals.
abstract: The rate of nuclear fusion from tunneling in very dense metallic hydrogen in the core of Jupiter is calculated to be 10{sup {minus}50} per hydrogen-deuterium pair per second. It is estimated that the width of the fusion barrier for deuterium in palladium or a similar metal must be reduced to, of order, 0.1 A for the fusion rate to be 10{sup {minus}25} per deuterium per second. If this scale is achieved, the ratios of various nuclear reaction rates will be very different for cold versus thermonuclear fusion.

title: Density dependence of nuclear neutrino-pair production.
abstract: 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.

title: Resolution of the magnetic moment problem in relativistic theories.
abstract: A Landau-Migdal approach to relativistic mean field theory of nuclear matter is used to define the single particle isoscalar current. By virtue of the near cancellation of scalar and vector potentials, this current is very close to the standard nonrelativistic isoscalar current; and hence the single particle isoscalar magnetic moment operator gives results in agreement with the nonrelativistic shell model. Calculations of magnetic moments for closed shell plus (or minus) one nucleon using this effective current operator recover the Schmidt values, thus resolving a longstanding problem with relativistic models of nuclear structure.

title: Meson exchange effects in parity violating electron-deuteron scattering.
abstract: We discuss heavy-meson exchange corrections in the context of parity violating quasielastic electron-deuteron scattering. We compute the meson exchange contributions to the isoscalar vector response function of the deuteron. In contrast to the case of heavy targets the corrections are found to be small.