The gyraton model describes a gravitational field of an object moving with the velocity of light which has finite energy and spin distributed during some finite time interval $L$. A gyraton may be considered as a classical toy model for a quantum wave packet of high-energy particles with spin. In this paper we study a head-on collision of two gyratons and black hole formation in this process. The goal of this study is to understand the role of the gravitational spin-spin interaction in the process of mini-black-hole formation in particle collisions. To simplify the problem, we consider several gyraton models with special profiles of the energy and spin density distribution. For these models we study the apparent horizon (AH) formation on the future edge of a spacetime region before interaction. We demonstrate that the AH forms only if the energy duration and the spin are smaller than some critical values, while the length of the spin distribution should be at least of the order of the system gravitational radius. We also study gravitational spin-spin interaction in the head-on collision of two gyratons under the assumption that the values of gyraton spins are small. We demonstrate that the metric in the interaction region for such gyratons depends on the relative helicities of incoming gyratons, and the collision of gyratons with oppositely directed spins allows the AH formation in a larger parameter region than in the collision of the gyratons with the same direction of spins. Some applications of the obtained results to the mini-black-hole production at the Large Hadron Collider in TeV gravity scenarios are briefly discussed.

Quantum fields near black hole horizons can be described in terms of an infinite set of $d=2$ conformal fields. In this paper, by investigating transformation properties of general higher-spin currents under a conformal transformation, we reproduce the thermal distribution of Hawking radiation in both cases of bosons and fermions. As a by-product, we obtain a generalization of the Schwarzian derivative for higher-spin currents.

We consider the question of properly defining energy and momenta for nonasymptotic Minkowskian spaces in general relativity. Only spaces of this type, whose energy, linear 3-momentum, and intrinsic angular momentum vanish, would be candidates for creatable universes, that is, for universes which could have arisen from a vacuum quantum fluctuation. Given a universe, we completely characterize the family of coordinate systems for which one could sensibly say that this universe is a creatable universe.

Precise measurements of the anisotropies in the cosmic microwave background enable us to do an accurate study on the form of the primordial power spectrum for a given set of cosmological parameters. In a previous paper [A. Shafieloo and T. Souradeep, Phys. Rev. D 70, 043523 (2004).], we implemented an improved (error sensitive) Richardson-Lucy deconvolution algorithm on the measured angular power spectrum from the first year of WMAP data to determine the primordial power spectrum assuming a concordance cosmological model. This recovered spectrum has a likelihood far better than a scale invariant, or, “best fit” scale free spectra ($\Delta \ln \mathcal{L}\approx 25$ with respect to the Harrison-Zeldovich spectrum, and, $\Delta \ln \mathcal{L}\approx 11$ with respect to the power law spectrum with $n_s=0.95$). In this paper we use the discrete wavelet transform (DWT) to decompose the local features of the recovered spectrum individually to study their effect and significance on the recovered angular power spectrum and hence the likelihood. We show that besides the infrared cutoff at the horizon scale, the associated features of the primordial power spectrum around the horizon have a significant effect on improving the likelihood. The strong features are localized at the horizon scale.

If annihilating MeV-scale dark matter particles are responsible for the observed 511 keV emission from the Galactic bulge, then new light gauge bosons which mediate the dark matter annihilations may have other observable consequences. In particular, if such a gauge boson exists and has even very small couplings to standard model neutrinos, cosmic neutrinos with $\sim \mathrm{TeV}$ energies will scatter with the cosmic neutrino background through resonant exchange, resulting in a distinctive spectral absorption line in the high-energy neutrino spectrum. Such a feature could potentially be detected by future high-energy neutrino telescopes.

The $O(\mathrm{MeV})$ spin-1 $U$ boson has been proposed to mediate the interaction among electron-positron and $O(\mathrm{MeV})$ dark matter, in order to account for the 511 keV $\gamma$-ray observation by SPI/INTEGRAL. In this paper the observability of such a kind of $U$ boson at BESIII is investigated through the processes $e^{+}{e}^{-}\to U\gamma$ and $e^{+}{e}^{-}\to J/\Psi \to e^{+}{e}^{-}U$. We find that BESIII and high luminosity B factories have a comparable capacity to detect such a $U$ boson. If the $U$ boson decays mainly into dark matter, i.e. invisibly, BESIII can measure the coupling between the $U$ boson and an electron-positron pair $g_{eR}$ (see text) down to $O({10}^{-5})$, and cover large parameter space which can account for 511 keV $\gamma$-ray observation. On the other hand, provided that $U$ decays mainly into the electron-positron, BESIII can detect $g_{eR}$ down to $O({10}^{-3})$, and it is hard to explore the 511 keV $\gamma$-ray measurement allowed parameter space due to the irreducible QED backgrounds.

We reexamine the rescattering mechanism for the X(3872), as a candidate for the 2P charmonium state ${\chi }_{c1}(2\mathrm{P})$, decaying to $J/\psi \rho (\omega )$ through exchanging $D^{(*)}$ mesons between intermediate states $D(\overline{D})$ and ${\overline{D}}^{*}(D^{*})$. We evaluate the dispersive part, as well as the absorptive one, of the rescattering amplitude and find that the contribution from the dispersive part is dominant even when X(3872) lies above the threshold of the neutral channel ${\mathrm{th}}_n=m_{D^0}+m_{D^{*0}}$. We predict $R_{\rho /\omega }\simeq 1$ for the $m_X$ region scanned by experiments. Meanwhile, we also estimate the rate of $X\to D^0{\overline{D}}^0{\pi }^0$. Our results favor a charmonium interpretation of X(3872) when it lies slightly below the threshold of $D^0{\overline{D}}^{*0}$. Furthermore, we evaluated the width of $X\to J/\psi \rho$ with the help of a phenomenological effective coupling constant $g_X$, and find the total width of X(3872) to be in the range of 1–2 MeV.

A general formalism for calculating the bulk viscosity of strange quark matter is developed. Contrary to the common belief that the nonleptonic processes alone give the dominant contribution to the bulk viscosity, the inclusion of the Urca processes is shown to play an important role at intermediate densities when the characteristic r-mode oscillation frequencies are not too high. The interplay of nonleptonic and Urca processes is analyzed in detail.

In recent literature on eternal inflation, a number of measures have been introduced which attempt to assign probabilities to different pocket universes by counting the number of each type of pocket according to a specific procedure. We give an overview of the existing measures, pointing out some interesting connections and generic predictions. For example, pairs of vacua that undergo fast transitions between themselves will be strongly favored. The resultant implications for making predictions in a generic potential landscape are discussed. We also raise a number of issues concerning the types of transitions that observers in eternal inflation are able to experience.

We consider the sum rule proposed by one of us (S. L. A.), obtained by taking the expectation value of an axial-vector commutator in a state with one pion. The sum rule relates the pion decay constant to integrals of pion-pion cross sections, with one pion off the mass shell. We remark that recent data on pion-pion scattering allow a precise evaluation of the sum rule. We also discuss the related Adler-Weisberger sum rule (obtained by taking the expectation value of the same commutator in a state with one nucleon), especially in connection with the problem of extrapolation of the pion momentum off its mass shell. We find, with current data, that both the pion-pion and pion-nucleon sum rules are satisfied to better than 6%, and we give detailed estimates of the experimental and extrapolation errors in the closure discrepancies.

We derive Feynman rules for the interactions of a single gravitino with (s)quarks and gluons/gluinos from an effective supergravity Lagrangian in nonderivative form and use them to calculate the hadroproduction cross sections and decay widths of single gravitinos. We confirm the results obtained previously with a derivative Lagrangian as well as those obtained with the nonderivative Lagrangian in the high-energy limit and elaborate on the connection between gauge independence and the presence of quartic vertices. We perform extensive numerical studies of branching ratios, total cross sections, and transverse-momentum spectra at the Fermilab Tevatron and the CERN LHC. From the latest CDF monojet cross section limit, we derive a new and robust exclusion contour in the gravitino-squark/gluino mass plane, implying that gravitinos with masses below $2\times {10}^{-5}$ to $1\times {10}^{-5}\mathrm{eV}$ are excluded for squark/gluino masses below 200 and 500 GeV, respectively. These limits are complementary to the one obtained by the CDF Collaboration, $1.1\times {10}^{-5}\mathrm{eV}$, under the assumption of infinitely heavy squarks and gluinos. For the LHC, we conclude that supersymmetric scenarios with light gravitinos will lead to a striking monojet signal very quickly after its startup.

The Balitsky-Kovchegov QCD equation for rapidity evolution describing saturation effects at high energy admits universal asymptotic traveling-wave solutions when the nonlinear damping becomes effective. The asymptotic solutions fall in universality classes depending only on some specific properties of the solution of the associated linear equation. We derive these solutions for the recent QCD formulations of the Balitsky-Kovchegov equation with running coupling constant obtained from quark-loop calculation. While the associated linear solutions depend in different ways with observables and higher-order effects, we show that the asymptotic traveling-wave solutions all belong to the same universality class whose solutions are given. Hence the influence of saturation stabilizes the QCD evolution with respect to higher-order effects and leads to universal features at high enough rapidity, such as the form of the traveling waves, the intercept of the saturation scale and geometric scaling in the square root of the rapidity.

In the framework of SU(2) gluodynamics, we derive the tensor structure of the neutral gluon polarization tensor in an Abelian homogeneous magnetic field at finite temperature and calculate it in the one-loop approximation in the Lorentz background field gauge. The imaginary time formalism and the Schwinger operator method are used. The latter is extended to the finite temperature case. The polarization tensor turns out to be nontransversal. It can be written as a sum of ten tensor structures with corresponding form factors. Seven tensor structures are transversal; three are not. We represent the form factors in terms of double-parametric integrals and the temperature sum which can be computed numerically. As applications we calculate the Debye mass and the magnetic mass of neutral gluons in the background field at high temperature. A comparison with the results of other authors is done.

We consider Lorentz-conserving noncommutative field theory to construct the Lorentz-conserving noncommutative standard model based on the gauge group $\mathrm{SU}(3)\times \mathrm{SU}(2)\times \mathrm{U}(1)$. We obtain the enveloping algebra-valued of Higgs field up to the second order of the noncommutativity parameter ${\theta }_{\mu \nu }$. We derive the action at the leading order and find new vertices which are absent in the ordinary standard model as well as the minimal noncommutative standard model. We briefly study the phenomenological aspects of the model.

Some kinks for non-Hermitian quantum field theories in $1+1$ dimensions are constructed. A class of models where the soliton energies are stable and real are found. Although these kinks are not Hermitian, they are symmetric under $PT$ transformations.

Current expectations on the signal-to-noise ratios and masses of supermassive black holes which the Laser Interferometer Space Antenna (LISA) can observe are based on using in matched filtering only the dominant harmonic of the inspiral waveform at twice the orbital frequency. Other harmonics will affect the signal-to-noise ratio of systems currently believed to be observable by LISA. More significantly, inclusion of other harmonics in our matched filters would mean that more massive systems that were previously thought to be not visible in LISA should be detectable with reasonable SNRs. Our estimates show that we should be able to significantly increase the mass reach of LISA and observe the more commonly occurring supermassive black holes of masses $\sim {10}^8{M}_{\odot }$. More specifically, with the inclusion of all known harmonics LISA will be able to observe even supermassive black hole coalescences with total mass $\sim {10}^8{M}_{\odot }({10}^9{M}_{\odot })$ (and mass ratio 0.1) for a low frequency cutoff of ${10}^{-4}\mathrm{Hz}$ (${10}^{-5}\mathrm{Hz}$) with an SNR up to $\sim 60$ ($\sim 30$) at a distance of 3 Gpc. This is important from the astrophysical viewpoint since observational evidence for the existence of black holes in this mass range is quite strong and binaries containing such supermassive black holes will be inaccessible to LISA if one uses as detection templates only the dominant harmonic.

We discuss geometrical properties of the horizon surface of five-dimensional rotating black holes and black rings. Geometrical invariants characterizing these 3D geometries are calculated. We obtain a global embedding of the 5D rotating black horizon surface into a flat space. We also describe the Kaluza-Klein reduction of the black ring solution (along the direction of its rotation) which, though it is nakedly singular, relates this solution to the 4D metric of a static black hole distorted by the presence of external scalar (dilaton) and vector (“electromagnetic”) fields. The properties of the reduced black hole horizon and its embedding in ${\mathbb{E}}^3$ are briefly discussed.

We examine the slepton masses of SUSYLR models and how they change due to the presence of light doubly-charged Higgs bosons. We discover that the measurement of the slepton masses could bound and even predict the value of the third generation Yukawa coupling of leptons to the $SU(2{)}_R$ triplets. We also consider the unification prospects for this model with the addition of left-handed, $B-L=0$ triplets—a model we call the triplet extended supersymmetric standard model (TESSM).

We investigate the correlated predictions of singlet extended MSSM models for direct detection and the cosmological relic density of the lightest neutralino. To illustrate the general effects of the singlet, we take heavy sleptons and squarks. We apply CERN LEP, $(g-2{)}_{\mu }$, and perturbativity constraints. We find that the WMAP upper bound on the cold dark matter density limits much of the parameter space to regions where the lightest neutralino can be discovered in recoil experiments. The results for the next-to-minimal supersymmetric standard model and $U(1{)}^{\prime }$-extended minimal supersymmetric standard model are typically similar to the MSSM since their light neutralinos have similar compositions and masses. In the nearly minimal supersymmetric standard model the neutralino is often very light and its recoil detection is within the reach of the CDMS II experiment. In general, most points in the parameter spaces of the singlet models we consider are accessible to the WARP experiment.