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We calculate the gravitational radiation background generated from boson star binaries formed in locally dense clusters with formation rate tracked by the regular star formation rate. We compute how the the frequency window in gravitational waves is affected by the boson field mass and repulsive self-coupling, anticipating constraints from EPTA and LISA. We also comment on the possible detectability of these binaries., 11 pages, 3 figures

We compute the configurational complexity (CC) for discrete soliton and rogue waves traveling along an Ablowitz-Ladik-Hirota (ALH) waveguide and modeled by a discrete nonlinear Schrodinger equation. We show that for a specific range of the soliton transverse direction κ propagating along the parametric time ζ ( t ) , CC reaches an evolving series of global minima. These minima represent maximum compressibility of information in the momentum modes along the Ablowitz-Ladik-Hirota waveguide. Computing the CC for rogue waves as a function of background amplitude modulation μ, we show that it displays two essential features: a maximum representing the optimal value for the rogue wave inception (the “gradient catastrophe”) and saturation representing the rogue wave dispersion into constituent wave modes. We show that saturation is achieved earlier for higher values of modulation amplitude as the discrete rogue wave evolves along time ζ ( t ) .

Spatially-bound objects across diverse length and energy scales are characterized by a binding energy. We propose that their spatial structure is mathematically encoded as information in their momentum modes and described by a measure known as configurational entropy (CE). Investigating solitonic Q-balls and stars with a polytropic equation of state $P = K{\rho}^{\gamma}$, we show that objects with large binding energy have low CE, whereas those at the brink of instability (zero binding energy) have near maximal CE. In particular, we use the CE to find the critical charge allowing for classically stable Q-balls and the Chandrasekhar limit for white dwarfs $({\gamma} = 4/3)$ with an accuracy of a few percent., Comment: 4 figures

Extremely long-lived, time-dependent, spatially-bound scalar field configurations are shown to exist in $d$ spatial dimensions for a wide class of polynomial interactions parameterized as $V(\phi) = \sum_{n=1}^h\frac{g_n}{n!}\phi^n$. Assuming spherical symmetry and if $V'', Comment: In press, Physics Letters B. 6 pages, 2 Postscript figures, uses revtex4.sty

We study weakly first order cosmological phase transitions in finite temperature field theories. Focusing on the standard electroweak theory and its minimal supersymmetric extension, we identify the regimes of Higgs masses for which the phase transition in these models proceeds by significant phase mixing and the coarsening of the subsequent domain network. This dynamics is distinct from that for strongly first order transitions, which proceed by the nucleation and propagation of critical bubbles. We describe how electroweak baryogenesis might take place in these models, explaining how our new picture can relax the sphaleron washout bound of traditional scenarios., 5 pages, 4 figures, RevTeX. Some extra clarifying discussion added. To appear in Phys. Lett. B

The study of nonlinear phenomena in systems with many degrees of freedom often relies on complex numerical simulations. In trying to model realistic situations, these systems may be coupled to an external environment which drives their dynamics. For nonlinear field theories coupled to thermal (or quantum) baths, discrete lattice formulations must be dealt with extreme care if the results of the simulations are to be interpreted in the continuum limit. Using techniques from renormalization theory, a self-consistent method is presented to match lattice results to continuum models. As an application, symmetry restoration in $\phi^4$ models is investigated., Comment: 15 pages RevTex, 12 postscript figures

The dynamics of first-order cosmological phase transitions is critically examined. In particular, criteria to estimate the strength of the transition are introduced. It is shown that for sufficiently weak transitions, thermal fluctuations away from the symmetric phase can efficiently populate the asymmetric phase at the critical temperature, leading to a mixing of the phases and to a different mechanism for the completion of the transition. These criteria are applied to the standard model electroweak phase transition.

We study the dynamics of cosmological phase transitions initiated from a state of thermal equilibrium. If the effective potential satisfies certain general conditions, a homogeneous phase of false vacuum will form as the Universe expands, and the transition will proceed by well-known bubble nucleation processes. If such conditions do not hold, the Universe may instead be filled with a two-phase emulsion. The evolution of the transition will be determined by the free energy difference between the two phases and by the expansion rate of the Universe. Thermal fluctuations between the phases will determine the final distribution of regions of the Universe in each phase as they freeze out. We develop a method to study the dynamics of such fluctuations, which we call sub-critical bubbles, and apply it to several situations of interest, including the symmetric and asymmetric double-well, and the Coleman-Weinberg scalar potentials. We show that in certain cases it is possible to avoid supercooling, with the transition being completed by sub-critical fluctuations. Possible applications to the electroweak phase transition are briefly discussed.

Urges to unite the laws of nature into an elegant whole are driven by unconscious impulses, obscuring the messy, life-giving reality of an imperfect universe

Einstein equations are derived for D-dimensional space-time that spontaneously compactify to the product M4 × Πi = 1αMdi in which the metric is taken to be of the generalized Robertson-Walker form. Cosmological solutions for these equations are studied with power law, oscillatory and exponential behaviour for the D-dimensional Einstein-Maxwell, N = 2, D = 10 and N = 1, D = 11 supergravity models. In the Einstein-Maxwell case the presence of a cosmological constant forces the extra dimensions to be static. Nevertheless, it is possible to find solutions with vanishing effective 4 dimensional cosmological constant with an expanding 4-dimensional space-time. In the supergravity models the requirement of having compact extra dimensions restricts the solutions to have expansion only in the 4-dimensional space-time. Matter contribution is added to the energy-momentum tensor in an attempt to find new solutions.

We discuss the thermodynamics of higher dimensional black holes with particular emphasis on a new class of spinning black holes which, due to the increased number of Casimir invariants, have additional spin degrees of freedom. In suitable limits, analytic solutions in arbitrary dimensions are presented for their temperature, entropy, and specific heat. In 5 + 1 and 9 + 1 dimensions, more general forms for these quantities are given. It is shown that the specific heat for a higher dimensional black hole is negative definite if it has only one non-zero spin parameter, regardless of the value of this parameter. We also consider equilibrium configurations with both massless particles and massive string modes.

We develop a first order formalism for the quantization of gravity. We take as canonical variables both the induced metric and the extrinsic curvature of the ( d − 1)-dimensional hyper- surfaces obtained by the foliation of the d -dimensional spacetime. After solving the constraint algebra we use the Dirac formalism to quantize the theory and obtain a new representation for the Wheeler-DeWitt equation, defined in the functional space of the extrinsic curvature. We also show how to obtain several different representations of the Wheeler-DeWitt equation by considering actions differing by a total divergence. In particular, the intrinsic and extrinsic time approaches appear in a natural way, as do equivalent representations obtained by functional Fourier transforms of appropriate variables. We conclude with some remarks about the construction of the Hilbert space within the first order formalism.

We obtain spherically symmetric solutions for scalar fields with a non-minimal coupling ξ|o|2R to gravity. We find, for zero-node fields of mass m, maximum masses and number of particles of order M max ∼0.73ξ 1 2 M 2 Planck /m , and N max ∼0.88 ξ 1 2 × M 2 Planck /m 2 respectively, for large positive ξ. For large negative ξ we find M max ∼0.66|ξ| 1 2 M 2 Planck /m , and N max ∼0.72|ξ| 1 2 × M 2 /m 2 Planck . We also calculate the critical mass and particle number for higher radial nodes of the scalar field and find that both quantities grow approximately linearly for large node number n.

The question of the stability of matter against gravitational collapse is of general interest to astrophysics. In this work we investigate the stability against small radial oscillations of equilibrium configurations of cold, gravitationally bound states of complex scalar fields, known as boson stars. These equilibrium configurations exhibit a mass profile against central density which is very similar to that of ordinary neutron stars, with a pronounced maximum mass at Mc = 0.633MPl2/m, where MPl is the Planck mass, for a certain value of the central density σc(0). We give analytical and numerical proof that configurations with central densities greater than σc(0) are unstable against radial perturbations by studying the behavior of the eigenfrequencies of the perturbations for different values of σ(0).

We show that compactifications of theories with extra dimensions are unstable if due to monopole configurations of an antisymmetric tensor field balanced against one-loop Casimir corrections. In the case of ten-dimensional supergravity it is possible, at least for a portion of the phase space, to achieve a stable compactification without fine-tuning by including the contribution of fermionic condensates to the monopole configurations.

We analyse d = 10, N = 2 supergravity and d = 10 Maxwell-Einstein theory with a cosmological constant for possible cosmologies. In the former case we find either an oscillating (3+1)-dimensional anti-de Sitter universe with a constant value for all fields on the remaining (internal) dimensions, which are CP 2 × S 2 , or all internal-dimension fields are changing in time. In the latter case a variety of solutions are possible of a power-law form, as well as the previous oscillating case. In the oscillating cases the induced cosmological constant is less than 10 −120 M p1 4 .

We propose a model for a gas of superstrings at high temperature, in which only string modes with lifetime long enough to be in equilibrium contribute to the bulk properties (so avoiding the limiting temperature typical of string models). The equation of state is calculated and the resulting cosmology shown to have a behaviour slightly different from a Friedmann soluiton. If only modes close to the leading Regge trajectory are considered a short lived inflationary cosmology is obtained.