Some Multi-Quark Potentials, Pseudo-Potentials and AdS/QCD

The static three-quark potential and pseudo-potential of a pure SU(3) gauge theory are studied in a five-dimensional framework known as AdS/QCD. The results support the Y-ansatz for the baryonic area law. A comparison with the quark-antiquark calculations shows the universality of the string tension as well as the spatial string tension. We also discuss extensions to SU(N) gauge theories.Comment: 18 pages, 7 figures; v2: a few sentences added and typos correcte

Normal-Superfluid Interface Scattering For Polarized Fermion Gases

We argue that, for the recent experiments with imbalanced fermion gases, a temperature difference may occur between the normal (N) and the gapped superfluid (SF) phase. Using the mean-field formalism, we study particle scattering off the N-SF interface from the deep BCS to the unitary regime. We show that the thermal conductivity across the interface drops exponentially fast with increasing $h/k_B T$, where $h$ is the chemical potential imbalance. This implies a blocking of thermal equilibration between the N and the SF phase. We also provide a possible mechanism for the creation of gap oscillations (FFLO-like states) as seen in recent studies on these systems.Comment: 4 pages, 3 figure

Cold Quark Matter, Quadratic Corrections and Gauge/String Duality

We make an estimate of the quadratic correction in the pressure of cold quark matter using gauge/string duality.Comment: 7 pages; v.2: reference added; v.3: reference and comments added, version to appear in PRD; v4. final version to appear in PRD; v.5: key reference adde

Two-photon correlations as a sign of sharp transition in quark-gluon plasma

The photon production arising due to time variation of the medium has been considered. The Hamilton formalism for photons in time-variable medium (plasma) has been developed with application to inclusive photon production. The results have been used for calculation of the photon production in the course of transition from quark-gluon phase to hadronic phase in relativistic heavy ion collisions. The relative strength of the effect as well as specific two- photon correlations have been evaluated. It has been demonstrated that the opposite side two-photon correlations are indicative of the sharp transition from the quark-gluon phase to hadrons.Comment: 23 pages, 2 figure

Some Thermodynamic Aspects of Pure Glue, Fuzzy Bags and Gauge/String Duality

The thermodynamic properties of a SU(3) gauge theory without quarks are calculated using a string formulation for 1.2T_c < T < 3T_c. The results are in good agreement with the lattice data. We also comment on SU(N) gauge theories.Comment: 10 pages, 5 figure

Scaling Violation and Gauge/String Duality

We explore the possibilities for scaling violation in gauge theories that have string duals. Like in perturbative QCD, short-distance behaviour yields logarithms that violate the scaling.Comment: 11 pages, 4 figures; v3: typos corrected, minor changes, to appear in PR

Andreev spectroscopy of doped HgTe quantum wells

We investigate the Andreev reflection process in high-mobility HgTe/CdTe quantum wells. We find that Andreev conductance probes the dynamics of massive 2+1 Dirac fermions, and that both specular Andreev reflection and retroreflection can be realized even in presence of a large mismatch between the Fermi wavelengths at the two sides of the normal/superconducting junction.Comment: 7 pages, 6 figure

Semiclassical theory in Andreev billiards: beyond the diagonal approximation

Recently semiclassical approximations have been successfully applied to study the effect of a superconducting lead on the density of states and conductance in ballistic billiards. However, the summation over classical trajectories involved in such theories was carried out using the intuitive picture of Andreev reflection rather than the semiclassical reasoning. We propose a method to calculate the semiclassical sums which allows us to go beyond the diagonal approximation in these problems. In particular, we address the question of whether the off-diagonal corrections could explain the gap in the density of states of a chaotic Andreev billiard.Comment: 11 page

Quasi two-dimensional superfluid Fermi gases

We study a quasi two-dimensional superfluid Fermi gas where the confinement in the third direction is due to a strong harmonic trapping. We investigate the behavior of such a system when the chemical potential is varied and find strong modifications of the superfluid properties due to the discrete harmonic oscillator states. We show that such quasi two-dimensional behavior can be created and observed with current experimental capabilities.Comment: In response to referee comments, minor changes from the earlier versio