18695813
Rotating dilaton black holes.
It is shown that an arbitrarily small amount of angular momentum can qualitatively change the properties of extremal charged black holes coupled to a dilaton. In addition, the gyromagnetic ratio of these black holes is computed and an exact rotating black string solution is presented.
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.
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.
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.
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.
21320167
Relativistic Love-Franey model: Covariant representation of the NN interaction for N-nucleus scattering.
A Lorentz invariant form of the NN amplitude is fit with a simple model which includes direct and exchange first Born terms from a number of ''mesons.'' The (complex) couplings and nucleon-meson form factors are adjusted to fit the NN amplitudes directly without iteration. The resulting parameters agree well with one-boson-exchange potentials and have a systematic and small energy dependence. Detailed analytic representations of the relativistic NN amplitudes are provided at lab energies of 135, 200, and 400 MeV. The model separation of the NN amplitudes into direct and exchange contributions does not involve sensitive cancellations and is contrasted with the very different nonrelativistic results. The model amplitudes are used to construct optical potentials in a relativistic impulse approximation using both pseudovector and pseudoscalar ..pi..-N coupling. The pseudoscalar result reproduces earlier relativistic impulse approximation calculations which diverge at low energies, while the pseudovector results are nearly constant with energy and in good agreement with phenomenological potentials.
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.
1357666
Hadron structure in a simple model of quark/nuclear matter.
We study a simple model for one-dimensional hadron matter with many of the essential features needed for examining the transition from nuclear to quark matter and the limitations of models based upon hadron rather than quark degrees of freedom. The dynamics are generated entirely by the quark confining force and exchange symmetry. Using Monte Carlo techniques, the ground-state energy, single-quark momentum distribution, and quark correlation function are calculated for uniform matter as a function of density. The quark confinement scale in the medium increases substantially with increasing density. This change is evident in the correlation function and momentum distribution, in qualitative agreement with the changes observed in deep-inelastic lepton scattering. Nevertheless, the ground-state energy is smooth throughout the transition to quark matter and is described remarkably well by an effective hadron theory based on a phenomenological hadron-hadron potential.
23575302
Relativistic effects on spin observables in quasielastic proton scattering.
The spin observables in quasielastic proton scattering are calculated in a simple relativistic model where the NN interaction is assumed to depend on the enhancement of the lower components of nucleon wave functions (because of strong nuclear potentials). This enhancement is characterized by an average effective mass M( of (0.8--0.9)M which is calculated in an eikonal model. The M( dependence of the NN interaction is taken from relativistic impulse approximation calculations. The polarization is found to decrease by 40 percent compared to the free NN value at 500 MeV. Next, simple formulas are provided to estimate the effects of spin-orbit potential distortions on spin observables. At 500 MeV and 18.5/sup 0/ in /sup 208/Pb, the polarization is decreased by 5 percent while D/sub l/'l and D/sub s/'s are decreased by 15 percent and D/sub n/n is almost unchanged.
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.