The color-electric flux tube of Abelian-projected (AP) SU(2) lattice gauge theory in the maximally Abelian gauge (MAG) is examined. It is shown that the lattice Gribov copy effect in the MAG is crucial for the monopole-related parts of the flux-tube profiles. Taking into account both the gauge fixing procedure and the effect of finite quark-antiquark distance properly, the scaling property of the flux-tube profile is confirmed. The quantitative relation between the measured AP flux tube and the flux-tube solution of the U(1) dual Abelian Higgs (DAH) model is also discussed. The fitting of the AP flux tube in terms of the DAH flux tube indicates that the vacuum can be classified as a weakly type-I dual superconductor.

We calculate the electromagnetic properties of the decuplet baryons in quenched and partially quenched chiral perturbation theory. We work at next-to-leading order in the chiral expansion, leading order in the heavy baryon expansion, and obtain expressions for the magnetic moments, charge radii, and electric quadrupole moments. The quenched calculation is shown to be pathological since only quenched chiral singularities are present at this order. We present the partially quenched results for both the $\mathrm{SU}\left(2\right)\mathrm{}$ and $\mathrm{SU}\left(3\right)\mathrm{}$ flavor groups and use the isospin limit in the latter. These results are necessary for proper extrapolation of lattice calculations of decuplet electromagnetic properties.

We investigate the production of the novel P-wave mesons $D_0^{*}$ and $D_1^{\prime }{(D}_1),$ identified as $J^P{=0\mathrm{}}^{+}$ and $1^{+},$ in heavy B meson decays, respectively. With the heavy quark limit, we give our modeling wave functions for the scalar meson $D_0^{*}.$ Based on the assumptions of color transparency and the factorization theorem, we estimate the branching ratios of $\overrightarrow{B}{D}_0^{*}\pi$ decays in terms of the obtained wave functions. Some remarks on $D_1^{(\prime )}$ production are also presented.

We consider the out-of-equilibrium evolution of a classical condensate field $\phi =〈\Phi 〉$ and its quantum fluctuations for a ${\Phi }^4$ model in $1+1$ dimensions with a double well potential. We use the two-particle point-irreducible (2PPI) formalism in the two-loop approximation. We compare our results to those obtained in the Hartree approximation, in the bare vertex approximation, and in the two-particle irreducible next-to-leading order large-$N$ approach, with thermal initial conditions. In the 2PPI scheme, we find that the system tends to the symmetric configuration at late times, as expected in the absence of spontaneous symmetry breaking.

We show that inflation can occur in the core of a Q ball.

We study “fuzzy funnel” solutions to the non-Abelian equations of motion of the D string. Our funnel describes $n^6/360\mathrm{}$ coincident D-strings ending on $n^3/6\mathrm{}$ D7-branes, in terms of a fuzzy six-sphere which expands along the string. We also provide a dual description of this configuration in terms of the world volume theory of the D7-branes. Our work makes use of an interesting nonlinear higher dimensional generalization of the instanton equations.

Motivated by recent suggestions that highly damped black hole quasinormal modes (QNM’s) may provide a link between classical general relativity and quantum gravity, we present an extensive computation of highly damped QNM’s of Kerr black holes. We perform the computation using two independent numerical codes based on Leaver’s continued fraction method. We do not limit our attention to gravitational modes, thus filling some gaps in the existing literature. As already observed by Berti and Kokkotas, the frequency of gravitational modes with $l=m=2\mathrm{}$ tends to ${\omega }_R=2\mathrm{}\Omega ,$ $\Omega$ being the angular velocity of the black hole horizon. We show that, if Hod’s conjecture is valid, this asymptotic behavior is related to reversible black hole transformations. Other highly damped modes with $m>\mathrm{}0\mathrm{}$ that we computed do not show a similar behavior. The real part of modes with $l=2\mathrm{}$ and $m<\mathrm{}0\mathrm{}$ seems to asymptotically approach a constant value ${\omega }_R\simeq -m\varpi ,$ $\varpi \simeq 0.12$ being (almost) independent of a. For any perturbing field, trajectories in the complex plane of QNM’s with $m=0\mathrm{}$ show a spiraling behavior, similar to the one observed for Reissner-Nordström black holes. Finally, for any perturbing field, the asymptotic separation in the imaginary part of consecutive modes with $m>\mathrm{}0\mathrm{}$ is given by $2\pi T_H$ ${(T}_H$ being the black hole temperature). We conjecture that for all values of l and $m>\mathrm{}0\mathrm{}$ there is an infinity of modes tending to the critical frequency for superradiance $({\omega }_R=m)$ in the extremal limit. Finally, we study in some detail modes branching off the so-called “algebraically special frequency” of Schwarzschild black holes. For the first time we find numerically that QNM multiplets emerge from the algebraically special Schwarzschild modes, confirming a recent speculation.

We find the gravitational resonance [quasinormal (QN)] modes of the higher-dimensional Schwarzschild and Reissner-Nordström black holes. The effect on the quasinormal behavior due to the presence of the $\lambda$ term is investigated. The QN spectrum is totally different for different signs of $\lambda .$ In more than four dimensions three types of gravitational modes were excited: scalar, vector, and tensor. They produce three different quasinormal spectra; thus, the isospectrality between scalar and vector perturbations, which takes place for $D=4\mathrm{}$ Schwarzschild and Schwarzschild–de Sitter black holes, is broken in higher dimensions, that is, the scalar-type gravitational perturbations, connected with fluctuations of the black hole horizon, which damp most slowly and therefore dominate during late time of the black hole ringing.

We construct a supergravity solution describing a charged rotating black ring with an $S^2\times S^1$ horizon in a five-dimensional asymptotically flat spacetime. In the neutral limit the solution is the rotating black ring recently found by Emparan and Reall. We determine the exact value of the lower bound on $J^2{/M}^3,$ where J is the angular momentum and M the mass; the black ring saturating this bound has a maximum entropy for the given mass. The charged black ring is characterized by a mass M, angular momentum J, and electric charge Q, and it also carries local fundamental string charge. The electric charge distributed uniformly along the ring helps support the ring against its gravitational self-attraction, so that $J^2{/M}^3$ can be made arbitrarily small while $Q/M$ remains finite. The charged black ring has an extremal limit in which the horizon coincides with the singularity.

We show that deviations of the quantum state of the inflaton from the thermal vacuum of inflation may leave an imprint in the CMB anisotropies. The quantum dynamics of the inflaton in such a state produces corrections to the inflationary fluctuations, which may be observable. Because these effects originate from IR physics below the Planck scale, they will dominate over any trans-Planckian imprints in any theory which obeys decoupling. Inflation sweeps away these initial deviations and forces its quantum state closer to the thermal vacuum. We view this as the quantum version of the cosmic no-hair theorem. Such imprints in the CMB may be a useful, independent test of the duration of inflation or of significant features in the inflaton potential about 60 e-folds before inflation ended, instead of an unlikely discovery of the signatures of quantum gravity. The absence of any such substructure would suggest that inflation lasted uninterrupted much longer than $O\left(100\right)\mathrm{}$ e-folds.

We derive the constraints set by several experiments on the quartessence Chaplygin model (QCM). In this scenario, a single fluid component drives the Universe from a nonrelativistic matter-dominated phase to an accelerated expansion phase behaving, first, like dark matter and in a more recent epoch like dark energy. We consider current data from SNIa experiments, statistics of gravitational lensing, FR IIb radio galaxies, and x-ray gas mass fraction in galaxy clusters. We investigate the constraints from this data set on flat Chaplygin quartessence cosmologies. The observables considered here are dependent essentially on the background geometry, and not on the specific form of the QCM fluctuations. We obtain the confidence region on the two parameters of the model from a combined analysis of all the above tests. We find that the best fit occurs close to the $\Lambda \mathrm{CDM}$ limit $(\alpha =0).\mathrm{}$ The standard Chaplygin quartessence $(\alpha =1)$ is also allowed by the data, but only at the $\sim 2\sigma$ level.

We propose an inflation model in supergravity, in which chaotic and hybrid inflation occurs successively, followed by new inflation. During hybrid inflation, adiabatic fluctuations with a running spectral index with $n_s>1\mathrm{}$ on a large scale and $n_s<1\mathrm{}$ on a smaller scale are generated, as favored by recent results of the first year Wilkinson Microwave Anisotropy Probe. The initial condition of new inflation is also set dynamically during hybrid inflation, and its duration and the amplitude of density fluctuations take appropriate values to help early star formation to realize early reionization.

We consider theories in which the standard model gauge fields propagate in extra dimensions whose size is around the electroweak scale. The standard model quarks and leptons may either be localized to a brane or propagate in the bulk. This class of theories includes models of Scherk-Schwarz supersymmetry breaking and universal extra dimensions. We consider the problem of stabilizing the volume of the extra dimensions. We find that for a large class of stabilization mechanisms the field which corresponds to fluctuations of the volume remains light even after stabilization, and has a mass in the ${10}^{-3}\mathrm{eV}$ range. In particular this is the case if stabilization does not involve dynamics at scales larger than the cutoff of the higher dimensional standard model, and if the effective theory below the compactification scale is four dimensional. The mass of this field is protected against large radiative corrections by the general covariance of the higher dimensional theory and by the weakness of its couplings, which are Planck suppressed. Its couplings to matter mediate forces whose strength is comparable to that of gravity and which can give rise to potentially observable deviations from Newton’s law at submillimeter distances. Current experiments investigating short distance gravity can probe extra dimensions too small to be accessible to current collider experiments. In particular for a single extra dimension stabilized by the Casimir energy of the standard model fields compactification radii as small as 5 inverse TeV are accessible to current submillimeter gravity experiments.

We consider a possible (parity conserving) interaction between the electromagnetic field F and a torsion field $T^{\alpha }$ of spacetime. For generic elementary torsion, gauge invariant coupling terms of lowest order fall into two classes that are both nonminimal and quadratic in torsion and respect Maxwell’s equations. The first class $\sim {\mathrm{FT}}^2$ admits $F$’s without the presence of charges and is excluded. The second class $\sim F^2{T}^2$ modifies the constitutive tensor of spacetime and can also be completely described in the framework of metricfree electrodynamics. We recognize three physical effects of the torsion: (i) An axion field that induces an optical activity into spacetime, (ii) a modification of the light cone structure that yields birefringence, and (iii) a torsion dependence of the velocity of light. We study these effects in the background of a Friedmann universe with torsion.

We propose an alternative for the Clebsch decomposition of currents in fluid mechanics, in terms of complex potentials taking values in a Kähler manifold. We reformulate classical relativistic fluid mechanics in terms of these complex potentials and rederive the existence of an infinite set of conserved currents. We perform a canonical analysis to find the explicit form of the algebra of conserved charges. The Kähler-space formulation of the theory has a natural supersymmetric extension in 4D space-time. It contains a conserved current, but also a number of additional fields complicating the interpretation. Nevertheless, we show that an infinite set of conserved currents emerges in the vacuum sector of the additional fields. This sector can therefore be identified with a regime of supersymmetric fluid mechanics. Explicit expressions for the current and the density are obtained.

We study gravitational theory in $1+2$ spacetime dimensions which is determined by the Lagrangian constructed as a sum of the Einstein-Hilbert term plus the two (translational and rotational) gravitational Chern-Simons terms. When the corresponding coupling constants vanish, we are left with purely Einstein theory of gravity. We obtain new exact solutions for the gravitational field equations with nontrivial material sources. Special attention is paid to plane-fronted gravitational waves (in case of the Maxwell field source) and to the circularly symmetric as well as the anisotropic cosmological solutions which arise for the ideal fluid matter source.

We present an action principle formulation for the study of the motion of an extended body in general relativity in the limit of a weak gravitational field. This gives the classical equations of motion for multipole moments of arbitrary order coupling to the gravitational field. In particular, a new force due to the octupole moment is obtained. The action also yields the gravitationally induced phase shifts in quantum interference experiments due to the coupling of all multipole moments.

We write the equation of geodesic deviations in the spacetime of pp waves in terms of the Newman-Penrose scalars and apply it to study gravitational waves in quadratic curvature gravity. We show that quadratic curvature gravity pp waves can have a transverse helicity-0 polarization mode and two transverse helicity-2 general-relativity-like wave polarizations. A concrete example is given in which we analyze the wave polarizations of an exact impulsive gravitational wave solution to quadratic curvature gravity.

de Sitter space-time has a one complex parameter family of invariant vacua for the theory of a free, massive scalar field. For most of these vacua, in an interacting scalar theory the one loop corrections diverge linearly for large values of the loop momentum. These divergences are not of a form that can be removed by a de Sitter invariant counterterm, except in the case of the Euclidean, or Bunch-Davies, vacuum.

We show that the boundary states are idempotent $B*B=B$ with respect to the star product of Hata-Itoh-Kugo-Kunitomo-Ogawa-type closed string field theory. Variations around the boundary state correctly reproduce the open string spectrum with the gauge symmetry. We explicitly demonstrate it for the tachyonic and massless vector modes. The idempotency relation may be regarded as the equation of motion of closed string field theory at a possible vacuum.