We show that the pseudogap of the quark density of states is formed in hot quark matter as a precursory phenomenon of the color superconductivity on the basis of a low-energy effective theory. We clarify that the decaying process of quarks near Fermi surface to a hole and the diquark soft mode $(\mathrm{q}\mathrm{q}{)}_{\mathrm{s}\mathrm{o}\mathrm{f}\mathrm{t}}$ is responsible for the formation of the pseudogap. Our result suggests that the pseudogap is a universal phenomenon in strong coupling superconductors.

The one-loop corrections to the lattice supersymmetric Ward-Takahashi identity (WTi) are investigated in the off-shell regime. In the Wilson formulation of the $N=1$ supersymmetric Yang-Mills theory, supersymmetry is broken by the lattice, by the Wilson term, and is softly broken by the presence of the gluino mass. However, the renormalization of the supercurrent can be realized in a scheme that restores the continuum supersymmetric WTi (once the on-shell condition is imposed). The general procedure used to calculate the renormalization constants and mixing coefficients for the local supercurrent is presented. The supercurrent not only mixes with the gauge invariant operator $T_{\mu }$. An extra mixing with other operators coming from the WTi appears. This extra mixing survives in the continuum limit in the off-shell regime and cancels out when the on-shell condition is imposed and the renormalized gluino mass is set to zero. Comparison with numerical results is also presented.

We study the free energy of a static quark-antiquark ($Q\overline{Q}$) pair at finite temperature in three flavor QCD with degenerate quark masses using $N_{\tau }=4$ and $6$ lattices with Asqtad staggered fermion action. The static free energy was calculated for different values of the quark mass and the entropy contribution at large distances has been extracted. We also calculate the renormalized Polyakov loop following the approach by Kaczmarek et al.

We study the rare top decays $t\to c{l}_i{l}_j$ ($l=\tau$ , $\mu$, or $e$) in the framework of topcolor-assisted technicolor (TC2) models. We find that the neutral top pion ${\pi }_t^0$ can produce significant contributions to these processes via the flavor changing couplings ${\pi }_t^0\overline{t}c$ and ${\pi }_t^0{l}_i{l}_j$. For the ${\pi }_t^0$ mass $m_{{\pi }_t}=150\mathrm{G}\mathrm{e}\mathrm{V}$ and the parameter $\epsilon =0.08$, the branching ratio $\mathrm{B}\mathrm{r}(t\to c\tau \tau )$ can reach $7.1\times {10}^{-7}$. Taking into account the constraints of the present experimental limit of the process $\mu \to e\gamma$ on the free parameters of TC2 models, we find that the value of $\mathrm{B}\mathrm{r}(t\to c\tau \mu )\approx \mathrm{B}\mathrm{r}(t\to c\tau e)$ is in the range of $1.8\times {10}^{-10}–1.7\times {10}^{-8}$.

We study supergravity duals of strongly coupled four-dimensional gauge theories formulated on compact quotients of hyperbolic spaces. The resulting background geometries are represented by Euclidean wormholes, which complicate establishing the precise gauge theory/string theory correspondence dictionary. These backgrounds suffer from the nonperturbative instabilities arising from the $D3\overline{D3}$ pair-production in the background four-form potential. We discuss conditions for suppressing this Schwingerlike instability. We find that Euclidean wormholes arising in this construction develop a naked singularity before they can be stabilized.

We investigate quantum corrections to the effective action of the universal hypermultiplet in the language of projective superspace. We rederive the recently found one-loop correction to the universal hypermultiplet moduli space geometry. The deformed metric is described as a superspace action in terms of a single function, homogeneous of first degree. Our framework leads us to a natural proposal for the nonperturbative moduli space metric induced by five-brane instantons.

In this paper, we study the question of quantization of quantum field theories in a general light-front frame. We quantize scalar and fermion as well as gauge field theories in a systematic manner carrying out the Hamiltonian analysis carefully. The decomposition of the fields into positive and negative frequency terms needs to be done carefully after which we show that the (anti) commutation relations for the quantum operators become frame independent. The frame dependence is completely contained in the functions multiplying these operators in the field decomposition. We derive the propagators from the vacuum expectation values of the time ordered products of the fields.

Recently, static and spherically symmetric configurations of globally regular self-gravitating scalar solitons were found. These configurations are unstable with respect to radial-linear perturbations. In this paper we study the dynamical evolution of such configurations and show that, depending on the sign of the initial perturbation, the solitons either collapse to a Schwarzschild black hole or else “explode” into an outward moving domain wall.

We investigate the relaxation and decay of a particle during inflation by implementing the dynamical renormalization group. This investigation allows us to give a meaningful definition for the decay rate in an expanding universe. As a prelude to a more general scenario, the method is applied here to study the decay of a particle in de Sitter inflation via a trilinear coupling to massless conformally coupled particles, both for wavelengths much larger and much smaller than the Hubble radius. For superhorizon modes we find that the decay is of the form ${\eta }^{{\Gamma }_1}$ with $\eta$ being conformal time and we give an explicit expression for ${\Gamma }_1$ to leading order in the coupling which has a noteworthy interpretation in terms of the Hawking temperature of de Sitter space-time. We show that if the mass $M$ of the decaying field is $\ll H$ then the decay rate during inflation is enhanced over the Minkowski space-time result by a factor $2H/\pi M$. For wavelengths much smaller than the Hubble radius we find that the decay law is $e$ with $C(\eta )$ the scale factor and $\alpha$ determined by the strength of the trilinear coupling. In all cases we find a substantial enhancement in the decay law as compared to Minkowski space-time. These results suggest potential implications for the spectrum of scalar density fluctuations as well as non-Gaussianities.

The intent of this paper is to point out that the accretion of a ghost condensate by black holes could be extremely efficient. We analyze steady-state spherically symmetric flows of the ghost fluid in the gravitational field of a Schwarzschild black hole and calculate the accretion rate. Unlike minimally coupled scalar field or quintessence, the accretion rate is set not by the cosmological energy density of the field, but by the energy scale of the ghost condensate theory. If hydrodynamical flow is established, it could be as high as a tenth of a solar mass per second for 10 MeV scale ghost condensate accreting onto a stellar-sized black hole, which puts serious constraints on the parameters of the ghost condensate model.

We consider very constrained versions of the minimal supersymmetric extension of the standard model (VCMSSMs) which, in addition to constraining the scalar masses $m_0$ and gaugino masses $m_{1/2}$ to be universal at some input scale, impose relations between the trilinear and bilinear soft supersymmetry-breaking parameters $A_0$ and $B_0$. These relations may be linear, as in simple minimal supergravity models, or nonlinear, as in the Giudice-Masiero mechanism for generating the Higgs-mixing $\mu$ term. We discuss the application of the electroweak vacuum conditions in VCMSSMs, which may be used to make a prediction for $\tan \beta$ as a function of $m_0$ and $m_{1/2}$ that is usually unique. We baseline the discussion of the parameter spaces allowed in VCMSSMs by updating the parameter space allowed in the CMSSM for fixed values of $\tan \beta$ with no relation between $A_0$ and $B_0$ assumed a priori, displaying contours of $B_0$ for a fixed input value of $A_0$, incorporating the latest CDF/D0 measurement of $m_t$ and the latest BNL measurement of $g_{\mu }-2$. We emphasize that phenomenological studies of the CMSSM are frequently not applicable to specific VCMSSMs, notably those based on minimal supergravity, which require $m_0=m_{3/2}$ as well as $A_0=B_0+m_0$. We then display $(m_{1/2},m_0)$ planes for selected VCMSSMs, treating in a unified way the parameter regions where either a neutralino or the gravitino is the lightest supersymmetric particle. In particular, we examine in detail the allowed parameter space for the Giudice-Masiero model.

In $d=3$ $\mathrm{S}\mathrm{U}(N)$ gauge theory, we study a scalar-field theory model of center vortices, and their monopolelike companions called nexuses, that furnishes an approach to the determination of so-called $k$-string tensions. This model is constructed from stringlike quantum solitons introduced previously, and exploits the well-known relation between string partition functions and scalar-field theories in $d=3$. A basic feature of the model is that center vortices corresponding to magnetic flux $J$ (in units of $2\pi /N$) are composites of $J$ elementary $J=1$ constituent vortices that come in $N-1$ types, with repulsion between like constituents and attraction between unlike constituents. The scalar-field theory is of a somewhat unusual type, involving $N$ scalar fields ${\varphi }_i$ (one of which is eliminated) that can merge, dissociate, and recombine while conserving flux $\mathrm{m}\mathrm{o}\mathrm{d}N$. The properties of these fields are deduced directly from the corresponding gauge-theory quantum solitons. Every vacuum Feynman graph of the theory corresponds to a real-space configuration of center vortices. We use qualitative features of this theory based on the vortex action to study the problem of $k$-string tensions (explicitly at large $N$, although large $N$ is in no way a restriction on the model in general), whose solution is far from obvious in center-vortex language. We construct a simplified dynamical picture of constituent-vortex merging, dissociation, and recombination, which allows in principle for the determination of vortex areal densities and $k$-string tensions. This picture involves pointlike molecules made of constituent atoms in $d=2$ which combine and disassociate dynamically. These molecules and atoms are cross sections of vortices piercing a test plane; the vortices evolve in a Euclidean “time” which is the location of the test plane along an axis perpendicular to the plane. A simple approximation to the molecular dynamics is compatible with $k$-string tensions that are linear in $k$ for $k\ll N$, as naively expected.

In AdS space the black hole horizon can be a hypersurface with a positive, zero, or negative constant curvature, resulting in different horizon topology. Thermodynamics and stability of black holes in AdS spaces are quite different for different horizon curvatures. In this paper we study thermodynamics and stability of hyperbolic charged black holes with negative constant curvature horizon in the grand canonical ensemble and canonical ensemble, respectively. They include hyperbolic Reissner-Nordström black holes in arbitrary dimensions and hyperbolic black holes in the $D=5,4,7$ gauged supergravities. It is found that associated Gibbs free energies are always negative, which implies that these black hole solutions are globally stable and the black hole phase is dominant in the grand canonical ensemble, but there is a region in the phase space where the black hole is not locally thermodynamically stable with a negative heat capacity for a given gauge potential. In the canonical ensemble, the Helmholtz free energies are not always negative and heat capacities with fixed electric charge are not always positive, which indicates that the Hawking-Page phase transition may happen and black holes are not always locally thermodynamically stable.

We study the impact of light gauge bosons on neutrino physics. We show that they can explain the NuTeV anomaly and also escape the constraints from neutrino experiments if they are very weakly coupled and have a mass of a few GeV. Lighter gauge bosons with stronger couplings could explain both the NuTeV anomaly and the positive anomalous magnetic moment of the muon. However, in the simple model we consider in this paper (say a purely vectorial extra U(1) current), they appear to be in conflict with the precise measurements of ${\nu }_{\mu }-e$, ${\nu }_e-e$ elastic scattering cross sections. The surprising agreement that we obtain between our naive model and the NuTeV anomaly for $m_{Z^{\prime }}\sim \mathrm{G}\mathrm{e}\mathrm{V}$ may be a coincidence. However, we think it is interesting enough to deserve attention and perhaps a more careful analysis, especially since a new light gauge boson is a very important ingredient for the Light Dark Matter scenario.

We investigate effects of discontinuous $K^{-}$-meson condensation on the phase transition from nuclear matter to color-flavor-locked quark matter. Two specific scenarios (one is a first-order transition via mixing of opposite-charged phases, whereas the other is a coexisting phase of the nuclear matter with $K^{-}$-meson condensation and the color-flavor-locked matter) are examined. It is found that the presence of electrically neutral color-flavor-locked matter is preceded by the coexisting phase in the sense of the hadron-quark continuity, once $K^{-}$-meson condensation occurs in a neutron star environment.

The region of small transverse momentum in $q\overline{q}$- and $gg$-initiated processes must be studied in the framework of resummation to account for the large, logarithmically enhanced contributions to physical observables. In this paper, we will calculate the fixed order next-to-leading order perturbative total and differential cross sections for both a Standard Model scalar Higgs boson and the Minimal Supersymmetric Standard Model's pseudoscalar Higgs boson in the Heavy Quark Effective Theory where the mass of the top quark is taken to be infinite. Resummation coefficients $B_g^{(2)},C_{gg}^{(2)}$ for the total cross-section resummation for the pseudoscalar case are given, as well as ${\overline{C}}_{gg}^{(1)}$ for the differential cross section.

We address the fine-tuning problem of dark energy cosmologies which arises when the dark energy density needs to initially lie in a narrow range in order for its present value to be consistent with observations. As recently noticed, this problem becomes particularly severe in canonical quintessence scenarios, when trying to reproduce the behavior of a cosmological constant, i.e., when the dark energy equation of state $w_Q$ approaches $-1$: these models may be reconciled with a large basin of attraction only by requiring a rapid evolution of $w_Q$ at low redshifts, which is in conflict with the most recent estimates from type Ia Supernovae discovered by Hubble space telescope. Next, we focus on scalar-tensor theories of gravity, discussing the implications of a coupling between the quintessence scalar field and the Ricci scalar (“extended quintessence”). We show that, even if the equation of state today is very close to $-1$, by virtue of the scalar-tensor coupling the quintessence trajectories still possess the attractive feature which allows to reach the present level of cosmic acceleration starting by a set of initial conditions which covers tens of orders of magnitude; this effect, entirely of gravitational origin, represents a new important consequence of the possible coupling between dark energy and gravity. We illustrate this effect in typical extended quintessence scenarios.

Quark pair annihilation into gluons is suppressed at large momenta due to the asymptotic freedom. As a consequence, mass eigenvalues of heavy states should be almost diagonal with respect to up and down quark masses, thereby breaking isospin. We suggest the particle observed by the SELEX Collaboration, $D_{sJ}(2632)$, to be to a good extent a $[cd][\overline{d}\overline{s}]$ state, which would explain why its $D^0{K}^{+}$ mode is anomalously suppressed with respect to $D_s^{+}\eta$. Predictions for the rates of the yet unobserved modes $D_s^{+}{\pi }^0$ and $D^{+}{K}^0$ are given.

We examine the radiative $\omega \to {\pi }^0\eta \gamma$ and $\rho \to {\pi }^0\eta \gamma$ decays in a phenomenological framework. We consider the vector meson dominance mechanism, chiral loops, intermediate $a_0$-meson and $\rho -\omega$ mixing. We find the values of the decay width coming from the different amplitudes and compare the results with other studies. We observe that the $a_0$-meson intermediate state is very important in the case of the $\rho \to {\pi }^0\eta \gamma$ decay and small in the other case for which vector meson dominance contribution is dominant.

We calculate puncture initial data corresponding to both single and binary black hole solutions of the constraint equations by means of a pseudospectral method applied in a single spatial domain. Introducing appropriate coordinates, these methods exhibit rapid convergence of the conformal factor and lead to highly accurate solutions. As an application we investigate small mass ratios of binary black holes and compare these with the corresponding test mass limit that we obtain through a semianalytical limiting procedure. In particular, we compare the binding energy of puncture data in this limit with that of a test particle in the Schwarzschild spacetime and find that it deviates by $50\%$ from the Schwarzschild result at the innermost stable circular orbit of Schwarzschild, if the ADM mass at each puncture is used to define the local black hole masses.