Linearized analysis of the Dvali–Gabadadze–Porrati brane model
We solve the Einstein equations in the Dvali–Gabadadze–Porrati model with a static, spherically symmetric matter distribution on the physical brane and obtain an exact expression for the gravitational field outside the source to the first order in the gravitational coupling. Although, this expression when confined on the physical brane reproduces the correct 4− D Newtonian potential for distances r s ⪡ r ⪡ λ , where λ is a characteristic length scale of the model, it does not coincide with the standard linearized form of the 4− D Schwarzschild metric. The solution reproduces the 5− D Schwarzschild metric in the linearized approximation for r ⪢ λ .

title: The Subleading Term of the Strong Coupling Expansion of the Heavy-Quark Potential in a N = 4 Super Yang-Mills Vacuum
abstract: Applying the AdS/CFT correspondence, the expansion of the heavy-quark potential of the N = 4 supersymmetric Yang-Mills theory at large Nc is carried out to the sub-leading term in the large ’t Hooft coupling at zero temperature. The strong coupling corresponds to the semiclassical expansion of the string-sigma model, the gravity dual of the Wilson loop operator, with the sub-leading term expressed in terms of functional determinants of fluctuations. The singularities of these determinants are examined and their contributions are evaluated numerically.

title: Bosonization of lattice fermions.
abstract: For any purely fermionic system on a lattice in arbitrary space dimension we prove that there is a different but well-defined system on the same lattice, consisting of both [ital bona] [ital fide] fermions and bosons with an interaction depending on a parameter [lambda], which characterizes a same-site repulsion between particles. The energy spectrum and the scattering matrix of the former are identical to those in the finite energy sector of the latter, in the limit [lambda][r arrow][infinity] (i.e., hard-core repulsion). This general theorem is applied to a resonance-boson model in a lattice fermion system, whose solution may have relevance to high-[ital T][sub [ital c]] superconductivity.

title: Gauge field fluctuations and first-order phase transition in color superconductivity.
abstract: We study the gauge field fluctuations in dense quark matter and determine the temperature of the induced first-order phase transition to the color-superconducting phase in weak coupling. We find that the local approximation of the coupling between the gauge potential and the order parameter, employed in the Ginzburg-Landau theory, has to be modified by restoring the full momentum dependence of the polarization function of gluons in the superconducting phase.

title: Effect of gauge-field fluctuations on the phase transition between normal and color-superconducting quark matter
abstract: Type-I color superconductors display a first-order phase transition due to thermal gauge-field fluctuations. We numerically evaluated the critical temperature of the first-order phase transition and the corresponding discontinuity of the diquark condensate at the critical point.

title: Absence of the London limit for the first-order phase transition to a color superconductor
abstract: We study the effects of gauge-field fluctuations on the free energy density of a homogeneous color superconductor in the color-flavor-locked (CFL) phase. Gluonic fluctuations induce a strong first-order phase transition, in contrast to electronic superconductors where this transition is weakly first order. The critical temperature for this transition is larger than the one corresponding to the diquark pairing instability. The physical reason is that the gluonic Meissner masses suppress long-wavelength fluctuations as compared to the normal conducting phase where gluons are massless, which stabilizes the superconducting phase. In weak coupling, we analytically compute the temperatures associated with the limits of metastability of the normal and superconducting phases, as well as the latent heat associated with the first-order phase transition. We then extrapolate our results to intermediate densities and numerically evaluate the temperature of the fluctuation-induced first-order phase transition, as well as the discontinuity of the diquark condensate at the critical point. We find that the London limit of magnetic interactions is absent in color superconductivity.

title: Fermions in a global monopole background
abstract: We study the scattering of fermions in a “global monopole” background metric. This is the four-dimensional analogue of the scattering on a cone in three dimensions. The scattering amplitude is exactly obtained. We then study massless fermion-dyon systems in such a background metric. The density of the S -wave fermion condensate is found to be given by a constant times the flat space value of Callan and Rubakov.