We investigate some features of the hydrodynamics and neutrino physics in the (predominantly) electron-positron plasma above a hyperaccreting disk (or torus) around a black hole, a conjectured engine for a short gamma ray burst. We suggest a possible scenario in which plasma in the region very near the black hole, energetically driven by neutrino annihilation, emerges as a subsonic wind, which in a spherically symmetrical case would decelerate as it moves out. In this case we argue that the plasma heating will be primarily through neutrino-electron and neutrino-positron scattering, and that this process will be important throughout a region considerably larger than that of the neutrino annihilation process. In simple solutions a relatively gentle anisotropy in the heating through this process can create an approximately conical sonic surface, aligned with the system’s axis. Inside this cone the fluid accelerates upwards as in standard jet models.

We perform simulations of an effective theory of SU(2) Wilson lines in three dimensions. We include a nonperturbative “fuzzy-bag” contribution, which is added to the one-loop perturbative potential for the Wilson line. We confirm that, at moderately weak coupling, this leads to eigenvalue repulsion in a finite region above the deconfining phase transition, which shrinks in the extreme weak-coupling limit. A nontrivial $Z(N)$ symmetric vacuum arises in the confined phase.

When constraining the primordial non-Gaussianity parameter $f_{\mathrm{NL}}$ with cosmic microwave background anisotropy maps, the bias resulting from the covariance between primordial non-Gaussianity and secondary non-Gaussianities to the estimator of $f_{\mathrm{NL}}$ is generally assumed to be negligible. We show that this assumption may not hold when attempting to measure the primordial non-Gaussianity out to angular scales below a few tens arcminutes with an experiment like Planck, especially if the primordial non-Gaussianity parameter is around the minimum detectability level with $f_{\mathrm{NL}}$ between 5 and 10. In the future, it will be necessary to jointly estimate the combined primordial and secondary contributions to the cosmic microwave background bispectrum and establish $f_{\mathrm{NL}}$ by properly accounting for the confusion from secondary non-Gaussianities.

We present a framework for de Sitter model building in type IIA string theory, illustrated with specific examples. We find metastable de Sitter (dS) minima of the potential for moduli obtained from a compactification on a product of two nil three-manifolds (which have negative scalar curvature) combined with orientifolds, branes, fractional Chern-Simons forms, and fluxes. As a discrete quantum number is taken large, the curvature, field strengths, inverse volume, and four-dimensional string coupling become parametrically small, and the de Sitter Hubble scale can be tuned parametrically smaller than the scales of the moduli, Kaluza Klein (KK), and winding mode masses. A subtle point in the construction is that although the curvature remains consistently weak, the circle fibers of the nilmanifolds become very small in this limit (though this is avoided in illustrative solutions at modest values of the parameters). In the simplest version of the construction, the heaviest moduli masses are parametrically of the same order as the lightest KK and winding masses. However, we provide a method for separating these marginally overlapping scales, and more generally the underlying supersymmetry of the model protects against large corrections to the low-energy moduli potential.

We have studied extreme mass-ratio inspirals (EMRIs) in spacetimes containing a rotating black hole and a non-self-gravitating torus with a constant distribution of specific angular momentum. We have found that the dissipative effect of the hydrodynamic drag exerted by the torus on the satellite is much smaller than the corresponding one due to radiation reaction, for systems such as those generically expected in active galactic nuclei and at distances from the central supermassive black hole (SMBH) which can be probed with the Laser Interferometer Space Antenna (LISA). However, given the uncertainty on the parameters of these systems, namely, on the masses of the SMBH and of the torus, as well as on its size, there exist configurations in which the effect of the hydrodynamic drag on the orbital evolution can be comparable to the radiation reaction one in phases of the inspiral which are detectable by the Laser Interferometer Space Antenna. This is the case, for instance, for a ${10}^6{M}_{\odot }$ SMBH surrounded by a corotating torus of comparable mass and with radius of ${10}^3–{10}^4$ gravitational radii, or for a ${10}^5{M}_{\odot }$ SMBH surrounded by a corotating ${10}^4{M}_{\odot }$ torus with radius of ${10}^5$ gravitational radii. Should these conditions be met in astrophysical systems, EMRI-gravitational waves could provide a characteristic signature of the presence of the torus. In fact, while radiation reaction always increases the inclination of the orbit with respect to the equatorial plane (i.e., orbits evolve towards the equatorial retrograde configuration), the hydrodynamic drag from a torus corotating with the SMBH always decreases it (i.e., orbits evolve towards the equatorial prograde configuration). However, even when initially dominating over radiation reaction, the influence of the hydrodynamic drag decays very rapidly as the satellite moves into the very strong-field region of the SMBH (i.e., $p\lesssim 5M$), thus allowing one to use pure-Kerr templates for the last part of the inspiral. Although our results have been obtained for a specific class of tori, we argue that they will be qualitatively valid also for more generic distributions of the specific angular momentum.

Second-order power spectra of cosmic microwave background (CMB) anisotropies due to random primordial perturbations at the matter-dominant stage are studied, based on the relativistic second-order theory of perturbations in flat cosmological models and on the second-order formula of CMB anisotropies derived by Mollerach and Matarrese. So far the second-order integrated Sachs-Wolfe effect has been analyzed using the three-point correlation or bispectrum. In this paper we derive the second-order term of power spectra given using the two-point correlation of temperature fluctuations. The second-order density perturbations are small, compared with the first-order ones. The second-order power spectra of CMB anisotropies, however, are not small at all, compared with the first-order power spectra, because at the early stage the first-order integrated Sachs-Wolfe effect is very small and the second-order integrated Sachs-Wolfe effect may be dominant over the first-order ones. So their characteristic behaviors may be measured through future precise observation and bring useful information on the structure and evolution of our universe in the future.

We consider here the decay of unstable particles in geodesic circular motion around compact objects. For the neutron, in particular, strong and weak decay are calculated by means of a semiclassical approach. Noticeable effects are expected to occur as one approaches the photonic circular orbit of realistic black holes. We argue that, in such a limit, the quasithermal spectrum inherent to extremely relativistic observers in circular motion plays a role similar to the Unruh radiation for uniformly accelerated observers.

We study the impact of hypercubic (HYP) smearing on the size of taste-breaking for staggered fermions, comparing to unimproved and to asqtad-improved staggered fermions. As in previous studies, we find a substantial reduction in taste-breaking compared to unimproved staggered fermions (by a factor of 4–7 on lattices with spacing $a\approx 0.1\mathrm{fm}$). In addition, we observe that discretization effects of next-to-leading order in the chiral expansion ($\mathcal{O}(a^2{p}^2)$) are markedly reduced by HYP smearing. Compared to asqtad valence fermions, we find that taste-breaking in the pion spectrum is reduced by a factor of 2.5–3, down to a level comparable to the expected size of generic $\mathcal{O}(a^2)$ effects. Our results suggest that, once one reaches a lattice spacing of $a\approx 0.09\mathrm{fm}$, taste-breaking will be small enough after HYP smearing that one can use a modified power counting in which $\mathcal{O}(a^2)\ll \mathcal{O}(p^2)$, simplify fitting to phenomenologically interesting quantities.

In the framework of the ${}^{3}P_0$ meson decay model, the strong decays of the $3{}^{1}S_0$ and $4{}^{1}S_0$ $s\overline{s}$ states are investigated. It is found that in the presence of the initial state mass being 2.24 GeV, the total widths of the $3{}^{1}S_0$ and $4{}^{1}S_0$ $s\overline{s}$ states are about 438 MeV and 125 MeV, respectively. Also, when the initial state mass varies from 2220 to 2400 MeV, the total width of the $4{}^{1}S_0$ $s\overline{s}$ state varies from about 100 to 132 MeV, while the total width of the $3{}^{1}S_0$ $s\overline{s}$ state varies from about 400 to 594 MeV. A comparison of the predicted widths and the experimental result of $(0.19\pm {0.03}_{-0.06}^{+0.04})\mathrm{GeV}$, the width of the $\eta (2225)$ with a mass of $({2.24}_{-0.02-0.02}^{+0.03+0.03})\mathrm{GeV}$ recently observed by the BES Collaboration in the radiative decay $J/\psi \to \gamma \varphi \varphi \to \gamma K^{+}{K}^{-}{K}_S^0{K}_L^0$, suggests that it would be very difficult to identify the $\eta (2225)$ as the $3{}^{1}S_0$ $s\overline{s}$ state, and the $\eta (2225)$ seams a good candidate for the $4{}^{1}S_0$ $s\overline{s}$ state.

This paper reports measurements of processes: $e^{+}{e}^{-}\to \gamma K_S^0{K}^{\pm }{\pi }^{\mp }$, $e^{+}{e}^{-}\to \gamma K^{+}{K}^{-}{\pi }^0$, $e^{+}{e}^{-}\to \gamma \varphi \eta$, and $e^{+}{e}^{-}\to \gamma \varphi {\pi }^0$. The initial-state radiated photon allows to cover the hadronic final state in the energy range from thresholds up to $\approx 4.6\mathrm{GeV}$. The overall size of the data sample analyzed is $232{\mathrm{fb}}^{-1}$, collected by the BABAR detector running at the PEP-II $e^{+}{e}^{-}$ storage ring. From the Dalitz plot analysis of the $K_S^0{K}^{\pm }{\pi }^{\mp }$ final state, moduli, and relative phase of the isoscalar and the isovector components of the $e^{+}{e}^{-}\to K{K}^{*}(892)$ cross section are determined. Parameters of $\varphi$ and $\rho$ recurrences are also measured, using a global fitting procedure which exploits the interconnection among amplitudes, moduli, and phases of the $e^{+}{e}^{-}\to K_S^0{K}^{\pm }{\pi }^{\mp }$, $K^{+}{K}^{-}{\pi }^0$, $\varphi \eta$ final states. The cross section for the OZI-forbidden process $e^{+}{e}^{-}\to \varphi {\pi }^0$, and the $J/\psi$ branching fractions to $K{K}^{*}(892)$ and $K^{+}{K}^{-}\eta$ are also measured.

The infrared behavior of the gluon and ghost propagators is studied in $SU(2)$ Euclidean Yang-Mills theory in the maximal Abelian gauge within the Gribov-Zwanziger framework. The nonperturbative effects associated with the Gribov copies and with the dimension-two condensates are simultaneously encoded into a local and renormalizable Lagrangian. The resulting behavior turns out to be in good agreement with the lattice data.

We study scattering and capture of particles by a rotating black hole in the five-dimensional spacetime described by the Myers-Perry metric. The equations of geodesic motion are integrable, and allow us to calculate capture conditions for a free particle sent towards a black hole from infinity. We introduce a three-dimensional impact parameter describing asymptotic initial conditions in the scattering problem for a given initial velocity. The capture surface in impact parameter space is a sphere for a nonrotating black hole, and is deformed for a rotating black hole. We obtain asymptotic expressions that describe such deformations for small rotational parameters, and use numerical calculations to investigate the arbitrary rotation case, which allows us to visualize the capture surface as extremal rotation is approached.

Models with dark energy decaying into dark matter have been proposed in cosmology to solve the coincidence problem. We study the effect of such coupling on the cosmic microwave background temperature anisotropies. The interaction changes the rate of evolution of the metric potentials and the growth rate of matter density perturbations and modifies the integrated Sachs-Wolfe component of cosmic microwave background temperature anisotropies, enhancing the effect. Cross correlation of galaxy catalogs with cosmic microwave background maps provides a model-independent test to constrain the interaction. We particularize our analysis for a specific interacting model and show that galaxy catalogs with median redshifts $z_m=0.1–0.9$ can rule out models with an interaction parameter strength of $c^2\simeq 0.1$ better than 99.95% confidence level. Values of $c^2\le 0.01$ are compatible with the data and may account for the possible discrepancy between the fraction of dark energy derived from Wilkinson microwave anisotropy probe 3 yr data and the fraction obtained from the integrated Sachs-Wolfe effect. Measuring the fraction of dark energy by these two methods could provide evidence of an interaction.

Parametric resonance or preheating is a plausible mechanism for bringing about the transition between the inflationary phase and a hot, radiation dominated universe. This epoch results in the rapid production of heavy particles far from thermal equilibrium and could source a significant stochastic background of gravitational radiation. Here, we present a numerical algorithm for computing the contemporary power spectrum of gravity waves generated in this post-inflationary phase transition for a large class of scalar-field driven inflationary models. We explicitly calculate this spectrum for both quartic and quadratic models of chaotic inflation, and low-scale hybrid models. In particular, we consider hybrid models with an inverted potential. These models have a very short and intense period of resonance which is qualitatively different from previous examples studied in this context, but we find that they lead to a similar spectrum of gravitational radiation.

Radiative decays ${\rm Y}(1s)\to \gamma ({\eta }^{\prime },\eta )$ are studied by an approach which has successfully predicted the ratio $\frac{\Gamma (J/\psi \to \gamma {\eta }^{\prime })}{\Gamma (J/\psi \to \gamma \eta )}$. Strong dependence on quark mass has been found in the decays $(J/\psi ,{\rm Y}(1s))\to \gamma ({\eta }^{\prime },\eta )$. Very small decay rates of ${\rm Y}(1s)\to \gamma ({\eta }^{\prime },\eta )$ are predicted.

It is well-known that the final state interaction plays an important role in the decays of $B$ meson. The contribution of the final state interaction, which is supposed to be long-distance effects, to the concerned processes can interfere with that of the short-distance effects produced via the tree and/or loop diagrams at quark-gluon level. The interference may provide a source for the direct $CP$ violation ${\mathcal{A}}_{CP}$ in the process $B_c^{+}\to D^0{\pi }^{+}$. We find that a typical value of ${\mathcal{A}}_{CP}$ when the final state interaction effect is taken into account can be about $-22\%$ which is different from that without the final state interaction effect. Therefore, when we extract information on $CP$ violation from the data which will be available at the Large Hadron Collider beauty experiment (LHCb) and the new experiments in $B$ factories, the contribution from the final state interaction must be included. This study may be crucial for searching new physics in the future.

Searches for supersymmetry are among the most exciting physics goals at run II of the Tevatron. In particular, in supersymmetric models with light charginos, neutralinos, and sleptons, associated chargino-neutralino production can potentially be observed as multilepton events with missing energy. We discuss how, in the generic TeV-scale minimal supersymmetric standard model (MSSM), the prospects for these chargino-neutralino searches are impacted by cosmological considerations, namely, the neutralino relic abundance and direct detection limits. We also discuss what an observation of chargino-neutralino production at the Tevatron would imply for the prospects of future direct dark-matter searches without assuming specific patterns of supersymmetry breaking.

In this paper bounds for $L_1$, $L_2$, and $L_3$ are obtained in chiral perturbation theory with three flavors. At the same time we test the compatibility of this theory with axiomatic principles. Following a recent paper we use dispersion relations to write positivity conditions that translate into bounds for the chiral low energy constants. As a first approach we consider the exact $SU(3{)}_V$ limit and notice that if a common mass of the order of that of the kaon is adopted for the octet of pseudo-Goldstone bosons the bounds have very large $\mathcal{O}(p^6)$ corrections. Once the positivity conditions are adapted to account for different masses, we correct the previous bounds for a physical kaon mass and find that they tighten. We observe an overlap between the experimentally determined region and the first principles forbidden region, in the space of parameters.

Axiomatic principles such as analyticity, unitarity, and crossing symmetry constrain the second derivative of the $\pi \pi$ scattering amplitudes in some channels to be positive in a region of the Mandelstam plane. Since this region lies in the domain of validity of chiral perturbation theory, we can use these positivity conditions to bound linear combinations of ${\overline{l}}_1$ and ${\overline{l}}_2$. We compare our predictions with those derived previously in the literature using similar methods. We compute the one-loop $\pi \pi$ scattering amplitude in the linear sigma model (LSM) using the $\overline{\mathrm{MS}}$ scheme, a result hitherto absent in the literature. The LSM values for ${\overline{l}}_1$ and ${\overline{l}}_2$ violate the bounds for small values of $m_{\sigma }/m_{\pi }$. We show how this can occur, while still being consistent with the axiomatic principles.