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The formulation of quasilocal conformal Killing horizons (CKH) is extended to include rotation. This necessitates that the horizon be foliated by 2-spheres which may be distorted. Matter degrees of freedom which fall through the horizon are represented by a real scalar field. We show that these rotating CKHs also admit a first law in differential form. [ABSTRACT FROM AUTHOR]

We examine quintessence models for dark energy in which the scalar field ɸ evolves near the vicinity of a local maximum or minimum in the potential V(ɸ), so that V(ɸ) can be approximated by a quadratic function of ɸ with no linear term. We generalize previous studies of this type by allowing the initial value of dɸ/dt to be nonzero. We derive an analytic approximation for w(a) and show that it is in excellent agreement with numerical simulations for a variety of scalar field potentials having local minima or maxima. We derive an upper bound on the present-day value of w as a function of the other model parameters and present representative limits on these models from observational data. This work represents a final generalization of previous studies using linear or quadratic approximations for V(ɸ). [ABSTRACT FROM AUTHOR]

If vector type perturbations are present in the primordial plasma before recombination, the generation of magnetic fields is known to be inevitable through the Harrison mechanism. In the context of the standard cosmological perturbation theory, nonlinear couplings of first-order scalar perturbations create second-order vector perturbations, which generate magnetic fields. Here we reinvestigate the generation of magnetic fields at second-order in cosmological perturbations on the basis of our previous study, and extend it by newly taking into account the time evolution of purely second-order vector perturbations with a newly developed second-order Boltzmann code. We confirm that the amplitude of magnetic fields from the product-terms of the first-order scalar modes is consistent with the result in our previous study. However, we find, both numerically and analytically, that the magnetic fields from the purely second-order vector perturbations partially cancel out the magnetic fields from one of the product-terms of the first-order scalar modes, in the tight coupling regime in the radiation dominated era. Therefore, the amplitude of the magnetic fields on small scales, k≳10 hMpc-1, is smaller than the previous estimates. The amplitude of the generated magnetic fields at cosmological recombination is about Brec = 5.0×10-24 Gauss on k = 5.0×10-1 hMpc-1. Finally, we discuss the reason for the discrepancies that exist in estimates of the amplitude of magnetic fields among other authors. [ABSTRACT FROM AUTHOR]

We consider a model of the early Universe which consists of two scalar fields: the inflaton and a second field which drives the stabilization of the Planck mass (or gravitational constant). We show that the nonminimal coupling of this second field to the Ricci scalar sources a nonadiabatic pressure perturbation. By performing a fully numerical calculation, we find, in turn, that this boosts the amplitude of the primordial power spectrum after inflation. [ABSTRACT FROM AUTHOR]

The Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach for the investigation of semihard processes is plagued by large next-to-leading corrections, both in the kernel of the universal BFKL Green's function and in the process-dependent impact factors, as well as by large uncertainties in the renormalization scale setting. All that calls for an optimization procedure of the perturbative series. In this respect, one of the most common methods is the Brodsky-Lepage-Mackenzie (BLM) one, which eliminates the renormalization scale ambiguity by absorbing the nonconformal β0 terms into the running coupling. In this paper, we apply the BLM scale setting procedure directly to the amplitudes (cross sections) of several semihard processes. We show that, due to the presence of β0 terms in the next-to-leading expressions for the impact factors, the optimal renormalization scale is not universal but depends both on the energy and on the type of process in question. [ABSTRACT FROM AUTHOR]

It is shown that the causal structure associated to string like solutions of the Faddeev-Niemi model is described by an effective metric. Remarkably, the surfaces characterizing the causal replacement depend on the energy momentum tensor of the background soliton and carry implicitly a topological invariant π3(S2). As a consequence, it follows that the preimage curves in R3 nontrivially define directions where the cones remain unchanged. We expect that these early results may be of importance in understanding time dependent solutions (collisions/scatterings) numerically or analytically. [ABSTRACT FROM AUTHOR]

We present rotating wormhole solutions in general relativity, which are supported by a phantom scalar field. These solutions evolve from the static Ellis wormhole, when the throat is set into rotation. As the rotational velocity increases, the throat deforms until, at a maximal value of the rotational velocity, an extremal Kerr solution is encountered. The rotating wormholes attain a finite mass and quadrupole moment. They exhibit ergospheres and possess bound orbits. [ABSTRACT FROM AUTHOR]

The computational technique of N-fold Mellin-Barnes (MB) integrals, presented in a companion paper by the same authors, is used to derive sets of series representations of the massive one-loop conformal three-point Feynman integral in various configurations. This shows the great simplicity and efficiency of the method in nonresonant cases (generic propagator powers) as well as some of its subtleties in the resonant ones (for unit propagator powers). We confirm certain results in the physics and mathematics literature and provide many new results, some of them dealing with the more general massive one-loop conformal n-point case. In particular, we prove two recent conjectures that give the massive one-loop conformal n-point integral (for generic propagator powers) in terms of multiple hypergeometric series. We show how these conjectures, that were deduced from a Yangian bootstrap analysis, are related by a tower of new quadratic transformations in hypergeometric functions theory. Finally, we also use our MB method to identify spurious contributions that can arise in the Yangian approach. [ABSTRACT FROM AUTHOR]