The Universe may harbor relics of the post-inflationary epoch in the form of a network of self-ordered scalar fields. Such fossils, while consistent with current cosmological data at trace levels, may leave too weak an imprint on the cosmic microwave background and the large-scale distribution of matter to allow for direct detection. The non-Gaussian statistics of the density perturbations induced by these fields, however, permit a direct means to probe for these relics. Here we calculate the bispectrum that arises in models of self-ordered scalar fields. We find a compact analytic expression for the bispectrum, evaluate it numerically, and provide a simple approximation that may be useful for data analysis. The bispectrum is largest for triangles that are aligned (have edges $k_1\simeq 2k_2\simeq 2k_3$) as opposed to the local-model bispectrum, which peaks for squeezed triangles ($k_1\simeq k_2\gg k_3$), and the equilateral bispectrum, which peaks at $k_1\simeq k_2\simeq k_3$. We estimate that this non-Gaussianity should be detectable by the Planck satellite if the contribution from self-ordering scalar fields to primordial perturbations is near the current upper limit.

We investigate the discovery potential of cubic-kilometer neutrino observatories such as IceCube to set stringent limits on the forbidden decays $\eta \to {\nu }_e{\overline{\nu }}_e$ and $\eta \to {\nu }_{\tau }{\overline{\nu }}_{\tau }$. The signatures for these decays are cascade events resulting from the charged-current reactions of ${\nu }_e$, ${\nu }_{\tau }$, ${\overline{\nu }}_e$, and ${\overline{\nu }}_{\tau }$ on nuclei in such detectors. Background cascade events are mainly due to ${\nu }_e$’s from atmospheric $\mu$, $K^{+}$, and $K_S^0$ decays and to a lesser extent from atmospheric ${\nu }_{\mu }$ neutral-current interactions with nuclei. A direct upper limit for the branching ratio $\eta \to {\nu }_{e,\tau }{\overline{\nu }}_{e,\tau }$ of $6.1\times {10}^{-4}$ at 90% CL can be achieved.

The $B$-meson distribution amplitude (DA) is defined as the matrix element of a quark-antiquark bilocal light-cone operator in the heavy-quark effective theory, corresponding to a long-distance component in the factorization formula for exclusive $B$-meson decays. The evolution equation for the $B$-meson DA is governed by the cusp anomalous dimension as well as the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-type anomalous dimension, and these anomalous dimensions give the “quasilocal” kernel in the coordinate-space representation. We show that this evolution equation can be solved analytically in the coordinate space, accomplishing the relevant Sudakov resummation at the next-to-leading logarithmic accuracy. The quasilocal nature leads to a quite simple form of our solution which determines the $B$-meson DA with a quark-antiquark light-cone separation $t$ in terms of the DA at a lower renormalization scale $\mu$ with smaller interquark separations $zt$ ($z\le 1$). This formula allows us to present rigorous calculation of the $B$-meson DA at the factorization scale $\sim \sqrt{m_b{\Lambda }_{\mathrm{QCD}}}$ for $t$ less than $\sim 1{\mathrm{GeV}}^{-1}$, using the recently obtained operator product expansion of the DA as the input at $\mu \sim 1\mathrm{GeV}$. We also derive the master formula, which reexpresses the integrals of the DA at $\mu \sim \sqrt{m_b{\Lambda }_{\mathrm{QCD}}}$ for the factorization formula by the compact integrals of the DA at $\mu \sim 1\mathrm{GeV}$.

The gauge invariant quark Green’s function with a path-ordered phase factor along a straight line is studied in two-dimensional QCD in the large-$N_c$ limit by means of an exact integrodifferential equation. Its spectral functions are analytically determined. They are infrared finite and lie on the positive real axis of the complex plane of the momentum squared variable, corresponding to momenta in the forward light cone. Their singularities are represented by an infinite number of threshold type branch points with power-law $-3/2$, starting at positive mass values, characterized by an integer number $n$ and increasing with $n$. The analytic expression of the Green’s function for all momenta is presented. The appearance of strong threshold singularities is suggestive of the fact that quarks could not be observed as asymptotic states.

We explore the consequences of treating the $X(3872)$ meson as a tetraquark bound state. As dynamical framework we employ a relativistic constituent quark model which includes infrared confinement in an effective way. We calculate the decay widths of the observed channels $X\to J/\psi +2\pi (3\pi )$ and $X\to {\overline{D}}^0+D^0+{\pi }^0$ via the intermediate off-shell states $X\to J/\psi +\rho (\omega )$ and $X\to \overline{D}+D^{*}$. For reasonable values of the size parameter ${\Lambda }_X$ of the $X(3872)$ we find consistency with the available experimental data. We also discuss the possible impact of the $X(3872)$ in a s-channel dominance description of the $J/\psi$ dissociation cross section.

We reanalyze the $B\to M$ tensor form factors in a covariant light-front quark model, where $M$ represents a vector meson $V$, an axial-vector meson $A$, or a tensor meson $T$. The treatment of masses and mixing angles in the $K_{1A,1B}$ systems is improved, where $K_{1A}$ and $K_{1B}$ are the ${}^{3}P_1$ and ${}^{1}P_1$ states of the axial-vector meson $K_1$, respectively. Rates of $B\to M\gamma$ decays are then calculated using the QCD factorization approach. The updated $B\to K^{*}\gamma$, $B\to K_1(1270)\gamma$, $K_1(1400)\gamma$, and $K_2\gamma$ rates agree with the data. The $K_1(1270)–K_1(1400)$ mixing angle is found to be about 51°. The sign of the mixing angle is fixed by the observed relative strength of $B\to K_1(1270)\gamma$ and $K_1(1400)\gamma$. The formalism is then applied to $B_s\to M$ tensor form factors. We find that the calculated $B_s\to \varphi \gamma$ rate is consistent with experiment, though in the lower end of the data. The branching fractions of $B_s\to f_1(1420)\gamma$ and $f_2^{\prime }(1525)\gamma$ are predicted to be of order ${10}^{-5}$ and it will be interesting to search for these modes. Rates on $B_s\to f_1(1285)\gamma$, $h_1(1380)\gamma$, $h_1(1170)\gamma$, $f_2(1270)\gamma$ decays are also predicted.

We outline a proof of factorization in exclusive processes, taking into account the presence of soft and collinear modes of arbitrarily low energy, which arise when the external lines of the process are taken on shell. Specifically, we examine the process of $e^{+}{e}^{-}$ annihilation through a virtual photon into two light mesons. In an intermediate step, we establish a factorized form that contains a soft function that is free of collinear divergences. In contrast, in soft-collinear effective theory, the low-energy collinear modes factor most straightforwardly into the soft function. We point out that the cancellation of the soft function, which relies on the color-singlet nature of the external hadrons, fails when the soft function contains low-energy collinear modes.

The EPR correlation has become an integral part of quantum communications as has general relativity in classical communication theory, however when combined an apparent deterioration is observed for spin states. We consider appropriate changes in directions of measurement to exploit full EPR entanglement for a pair of particles and show that it can be deduced only up to the outer event horizon of a Kerr-Newman black hole, even in the case of a freely falling observer.

We use a numerical code to consider the nonlinear processes arising when a Reissner-Nordström black hole is irradiated by an exotic scalar field ( modeled as a free massless scalar field with an opposite sign for its energy-momentum tensor). These processes are quite different from the processes arising in the case of the same black hole being irradiated by a pulse of a normal scalar field. In our case, we did not observe the creation of a spacelike strong singularity in the $T$ region of the space-time. We investigate the antifocusing effects in the gravity field of the exotic scalar field with the negative energy density and the evolution of the mass function. We demonstrate the process of the vanishing of the black hole when it is irradiated by a strong pulse of an exotic scalar field.

We investigate a scenario in which neutrinos are coupled to a pseudoscalar degree of freedom $\phi$ and where decays ${\nu }_1\to {\nu }_2+\phi$ and inverse decays are the responsible mechanism for obtaining equilibrium. In this context we discuss the implication of the invisible neutrino decay on the neutrino-pseudoscalar coupling constant and the neutrino lifetime. Assuming the realistic scenario of a thermal background of neutrinos and pseudoscalar we update the bound on the (off-diagonal) neutrino-pseudoscalar coupling constant to $g<2.6\times {10}^{-13}$ and the bound on the neutrino lifetime to $\tau >1\times {10}^{13}\mathrm{s}$. Furthermore we confirm analytically that kinetic equilibrium is delayed by two Lorentz $\gamma$ factors—one for time dilation of the (decaying) neutrino lifetime and one from the opening angle. We have also confirmed this behavior numerically.

We consider two new aspects of extensive air shower development universality allowing to make an accurate estimation of muon and electromagnetic (EM) shower contents in two independent ways. In the first case, to get the muon (or EM) signal in water Cherenkov tanks or in scintillator detectors, it is enough to know the vertical depth of the shower maximum $X_{\max }^{\mathrm{v}}$ and the total signal in the ground detector. In the second case, the EM signal can be calculated from the primary particle energy and the zenith angle. In both cases, the parametrizations of muon and EM signals are almost independent on the primary particle nature, energy and zenith angle. Implications of the considered properties for mass composition and hadronic interaction studies are briefly discussed. The present study is performed on 28 000 proton, oxygen, and iron showers, generated with CORSIKA 6.735 for the $E^{-1}$ spectrum in the energy range $\lg (E/\mathrm{eV})=18.5–20$ and uniformly distributed in ${cos}^2\theta$ in the zenith angle interval $\theta =0°–65°$ for QGSJET II/Fluka interaction models.

The tensor contribution to the $V$-mode polarization induced by a magnetized plasma at last scattering vanishes exactly when the magnetic field is parallel to the direction of propagation of the gravitational wave. For propagation perpendicular to the magnetic field orientation the effect depends on the ratio between the Larmor frequency of the electrons and the observational frequency. If the source term of the $V$-mode equation is averaged over the directions of the magnetic field, the circular polarization evolves independently from all the other Stokes parameters.

A standard quarter-wavelength multilayer optical coating will produce the highest reflectivity for a given number of coating layers, but in general it will not yield the lowest thermal noise for a prescribed reflectivity. Coatings with the layer thicknesses optimized to minimize thermal noise could be useful in future generation interferometric gravitational wave detectors where coating thermal noise is expected to limit the sensitivity of the instrument. We present the results of direct measurements of the thermal noise of a standard quarter-wavelength coating and a low noise optimized coating. The measurements indicate a reduction in thermal noise in line with modeling predictions.

In this brief report we explore the full realization of the dynamical symmetry breaking of an 3-3-1 model to $U(1{)}_{em}$ considering a model based on $SU(2{)}_{\mathrm{TC}}\otimes SU(3{)}_L\otimes U(1{)}_X$. We compute the mass generated for the charged and neutral gauge bosons of the model that result from the symmetry breaking, and verify the equivalence between a 3-3-1 model with a scalar content formed by the set of the fundamental scalar bosons $\chi ,\rho$ and $\eta$ with a 3-3-1 model where the dynamical symmetry breaking is implanted by the system formed by the set of composite bosons ${\Phi }_T,{\Phi }_{\mathrm{TC}(1)}$ and ${\Phi }_{\mathrm{TC}(2)}$. In this model the minimal composite scalar content is fixed by the condition of the cancellation of triangular anomaly in the technicolor (TC) sector.

An analysis of spin independent neutralino-proton cross sections ${\sigma }_{\mathrm{SI}}(\chi p)$ that includes this low mass region is given. The analysis is done in minimal supersymmetric standard model (MSSM) with radiative electroweak symmetry breaking (REWSB). It is found that cross sections as large as ${10}^{-40}{\mathrm{cm}}^2$ can be accommodated in MSSM within the REWSB framework. However, inclusion of sparticle mass limits from current experiments, as well as lower limits on the Higgs searches from the Tevatron, and the current experimental upper limit on $B_s\to {\mu }^{+}{\mu }^{-}$ significantly limit the allowed parameter space reducing ${\sigma }_{\mathrm{SI}}(\chi p)$ to lie below $\sim {10}^{-41}{\mathrm{cm}}^2$ or even lower for neutralino masses around 10 GeV. These cross sections are an order of magnitude lower than the cross sections needed to explain the reported data in the recent dark matter experiments in the low neutralino mass region.

We study the potential of the exclusive $pp\to p{\ell }^{-}{\ell }^{+}p$ process to probe excited leptons at the LHC, which is known to be one of the cleanest channels at the hadron colliders. The sensitivity of the model parameters is obtained at 95% confidence level by considering three forward detector acceptances: $0.0015<\xi <0.5$, $0.0015<\xi <0.15$, and $0.1<\xi <0.5$.

We adopt a Markov chain Monte Carlo method to examine various new physics models which can generate the forward-backward asymmetry in top quark pair production observed at the Tevatron by the CDF Collaboration. We study the following new physics models: (1) exotic gluon $G^{\prime }$, (2) extra $Z^{\prime }$ boson with flavor-conserving interaction, (3) extra $Z^{\prime }$ with flavor-violating $u\mathrm{\text{−}}t\mathrm{\text{−}}{Z}^{\prime }$ interaction, (4) extra $W^{\prime }$ with flavor-violating $d\mathrm{\text{−}}t\mathrm{\text{−}}{W}^{\prime }$ interaction, and (5) extra scalars $S$ and $S^{\pm }$ with flavor-violating $u\mathrm{\text{−}}t\mathrm{\text{−}}S$ and $d\mathrm{\text{−}}t\mathrm{\text{−}}{S}^{\pm }$ interactions. After combining the forward-backward asymmetry with the measurement of the top pair production cross section and the $t\overline{t}$ invariant mass distribution at the Tevatron, we find that an axial vector exotic gluon $G^{\prime }$ of mass about 1 TeV or 2 TeV or a $W^{\prime }$ of mass about $2\mathrm{TeV}$ offer an improvement over the standard model. The other models considered do not fit the data significantly better than the standard model. We also emphasize a few points that have been long ignored in the literature for new physics searches: (1) heavy resonance width effects, (2) renormalization scale dependence, and (3) next-to-leading order corrections to the $t\overline{t}$ invariant mass spectrum. We argue that these three effects are crucial to test or exclude new physics effects in the top quark pair asymmetry.

Using a large sample ($\approx 11800$ events) of $D^{+}\to K^{-}{\pi }^{+}{e}^{+}{\nu }_e$ and $D^{+}\to K^{-}{\pi }^{+}{\mu }^{+}{\nu }_{\mu }$ decays collected by the CLEO-c detector running at the $\psi (3770)$, we measure the helicity basis form factors free from the assumptions of spectroscopic pole dominance and provide new, accurate measurements of the absolute branching fractions for $D^{+}\to {\overline{K}}^{*0}{e}^{+}{\nu }_e$ and $D^{+}\to {\overline{K}}^{*0}{\mu }^{+}{\nu }_{\mu }$ decays. We find branching fractions which are consistent with previous world averages. Our measured helicity basis form factors are consistent with the spectroscopic pole dominance predictions for the three main helicity basis form factors describing $D^{+}\to {\overline{K}}^{*0}{\ell }^{+}{\nu }_{\ell }$ decay. The ability to analyze $D^{+}\to K^{-}{\pi }^{+}{\mu }^{+}{\nu }_{\mu }$ allows us to make the first nonparametric measurements of the mass-suppressed form factor. Our result is inconsistent with existing lattice QCD calculations. Finally, we measure the form factor that controls nonresonant $s$-wave interference with the $D^{+}\to {\overline{K}}^{*0}{\ell }^{+}{\nu }_{\ell }$ amplitude and search for evidence of possible additional nonresonant $d$- or $f$-wave interference with the ${\overline{K}}^{*0}$.

The Jackiw-Nair description of anyons combines spin-1 topologically massive fields with the discrete series representation of the Lorentz algebra, which has fractional spin. In the Dirac-Majorana formulation the spin-1 part is replaced by the spin $1/2$ planar Dirac equation. The two models are shown to belong to an $N=1$ supermultiplet, which carries a super-Poincaré symmetry.

Mallett has exhibited a cylindrically symmetric spacetime containing closed timelike curves produced by a light beam circulating around a line singularity. I analyze the static version of this spacetime obtained by setting the intensity of the light to zero. Some null geodesics can escape to infinity, but all timelike geodesics in this spacetime originate and terminate at the singularity. Freely falling matter originally at rest quickly attains relativistic velocity inward and is destroyed at the singularity.