We reexamine the interesting possibility of utilizing the Glashow resonance (GR) channel ${\overline{\nu }}_e+e^{-}\to W^{-}\to \mathrm{\text{anything}}$ to discriminate between the ultrahigh-energy (UHE) cosmic neutrinos originating from $p\gamma$ and $pp$ collisions in an optically thin source of cosmic rays. We propose a general parametrization of the initial neutrino flavor composition by allowing the ratios ${\Phi }_{{\pi }^{-}}^{p\gamma }/{\Phi }_{{\pi }^{+}}^{p\gamma }$ and ${\Phi }_{{\pi }^{-}}^{pp}/{\Phi }_{{\pi }^{+}}^{pp}$ to slightly deviate from their conventional values. A relationship between the typical source parameter $\kappa \equiv ({\Phi }_{{\pi }^{+}}^{p\gamma }+{\Phi }_{{\pi }^{-}}^{p\gamma })/({\Phi }_{{\pi }^{+}}^{pp}+{\Phi }_{{\pi }^{-}}^{pp}+{\Phi }_{{\pi }^{+}}^{p\gamma }+{\Phi }_{{\pi }^{-}}^{p\gamma })$ and the working observable of the GR $R_0\equiv {\Phi }_{{\overline{\nu }}_e}^{\mathrm{T}}/({\Phi }_{{\nu }_{\mu }}^{\mathrm{T}}+{\Phi }_{{\overline{\nu }}_{\mu }}^{\mathrm{T}})$ at a neutrino telescope is derived, and the numerical dependence of $R_0$ on $\kappa$ is illustrated by taking account of the latest experimental data on three neutrino mixing angles. It is shown that a measurement of $R_0$ is in principle possible to identify the pure $p\gamma$ interaction ($\kappa =1$), the pure $pp$ interaction ($\kappa =0$), or a mixture of both of them ($0<\kappa <1$) at a given source of UHE cosmic neutrinos. The event rate of the GR signal against the background is also estimated.

We present a new high precision measurement of parity violation in the weak interaction, using polarized muon decay. The TWIST Collaboration has measured $P_{\mu }^{\pi }\xi$, where $P_{\mu }^{\pi }$ is the polarization of the muon in pion decay and $\xi$ describes the intrinsic asymmetry in muon decay. We find $P_{\mu }^{\pi }\xi =1.00084\pm 0.00029(\mathrm{stat}.{)}_{-0.00063}^{+0.00165}(\mathrm{syst}.)$, in good agreement with the standard model prediction of $P_{\mu }^{\pi }=\xi =1$. Our result is a factor of 7 more precise than the pre-TWIST value, setting new limits in left-right symmetric electroweak extensions to the standard model.

We report a measurement of the mass of the top quark in $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ final states of $p\overline{p}\to t\overline{t}$ data corresponding to $2.6{\mathrm{fb}}^{-1}$ of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. A matrix-element method is developed that combines an in situ jet energy calibration with our standard jet energy scale derived from studies of $\gamma +\mathrm{\text{jet}}$ and dijet events. We then implement a flavor-dependent jet-response correction through a novel approach. This method is used to measure a top-quark mass of $m_t=176.01\pm 1.64\mathrm{GeV}$. Combining this result with our previous result obtained on an independent data set, we measure a top-quark mass of $m_t=174.94\pm 1.49\mathrm{GeV}$ for a total integrated luminosity of $3.6{\mathrm{fb}}^{-1}$.

In this paper we report a measurement of the $t\overline{t}$ production cross section in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ using data corresponding to an integrated luminosity of $2.2{\mathrm{fb}}^{-1}$ collected with the CDF II detector at the Tevatron accelerator. We select events with significant missing transverse energy and high jet multiplicity. This measurement vetoes the presence of explicitly identified electrons and muons, thus enhancing the tau contribution of $t\overline{t}$ decays. Signal events are discriminated from the background using a neural network, and heavy flavor jets are identified by a secondary-vertex tagging algorithm. We measure a $t\overline{t}$ production cross section of $7.99\pm 0.55(\mathrm{stat})\pm 0.76(\mathrm{syst})\pm 0.46(\mathrm{lumi})$ pb, assuming a top mass $m_{\mathrm{top}}=172.5\mathrm{GeV}/c^2$, in agreement with previous measurements and standard model predictions.

The attractor mechanism governs the near-horizon geometry of extremal black holes in ungauged four-dimensional $N=2$ supergravity theories and in Calabi-Yau compactifications of string theory. In this paper, we study a natural generalization of this mechanism to solutions of arbitrary 4D $N=2$ gauged supergravities. We define generalized attractor points as solutions of an ansatz which reduces the Einstein, gauge field, and scalar equations of motion to algebraic equations. The simplest generalized attractor geometries are characterized by nonvanishing constant anholonomy coefficients in an orthonormal frame. Basic examples include Lifshitz and Schrödinger solutions, as well as anti-de Sitter and de Sitter vacua. There is a generalized attractor potential whose critical points are the attractor points, and its extremization explains the algebraic nature of the equations governing both supersymmetric and nonsupersymmetric attractors.

It is shown that spacetime-dependent gauge couplings do not completely break gauge invariance. We demonstrate this in various gauge theories.

We investigate classical and quantum correlations of a quantum field in the inflationary universe using a particle detector model. By considering the entanglement and correlations between two comoving detectors interacting with a scalar field, we find that the entanglement between the detectors becomes zero after their physical separation exceeds the Hubble horizon. Furthermore, the quantum discord, which is defined as the quantum part of total correlation, approaches zero on the super horizon scale. These behaviors support the appearance of the classical nature of the quantum fluctuation generated during the inflationary era.

We derive the higher-dimensional generalization of Penrose-Tod equation describing past horizon in Robinson-Trautman spacetimes with a cosmological constant and pure radiation. Existence of its solutions in $D>4$ dimensions is proved using tools for nonlinear elliptic partial differential equations. We show that this horizon is naturally a trapping and a dynamical horizon. The findings generalize results from $D=4$.

The main goal of the present paper is to study how polarization of photons affects their motion in a gravitational field created by a rotating massive compact object. We study propagation of the circularly polarized beams of light in a stationary gravitational field. We use ($3+1$)-form of the Maxwell equations to derive a master equation for the propagation of monochromatic electromagnetic waves of the frequency $\omega$ with a given helicity. We first analize its solutions in the high frequency approximation using the “standard” geometrical optics approach. After that we demonstrate how this “standard” approach can be modified in order to include the effect of the helicity of photons on their motion. Such an improved method reproduces the standard results of the geometrical optics at short distances. However, it modifies the asymptotic behavior of the circularly polarized beams in the late-time regime. We demonstrate that the corresponding equations for the circularly polarized beam can be effectively obtained by modification of the background geometry by including a small factor proportional to ${\omega }^{-1}$ whose sign corresponds to photon helicity. We obtain the modified equations for circularly polarized rays by using such a “renormalization” procedure, and calculate the corresponding renormalization term for the Kerr geometry.

We examine the possibility that circles in the cosmic microwave background could be formed by the interaction of a gravitational wave pulse emitted in some pre-big-bang phase of the universe with the last scattering surface. We derive the expected size distribution of such circles, as well as their typical ring width and (for concentric circles) angular separation. We apply these results, in particular, to conformal cyclic cosmology, ekpyrotic cosmology as well as loop quantum cosmology with and without inflation in order to determine how the predicted geometric properties of these circles would vary from one model to the other, and thus, if detected, could allow us to differentiate between various pre-big-bang cosmological models. We also obtain a relation between the angular ring width and the angular radius of such circles that can be used in order to determine whether or not circles observed in the cosmic microwave background are due to energetic pre-big-bang events.

In the picture of eternal inflation, our observable universe resides inside a single bubble nucleated from an inflating false vacuum. Many of the theories giving rise to eternal inflation predict that we have causal access to collisions with other bubble universes, providing an opportunity to confront these theories with observation. We present the results from the first observational search for the effects of bubble collisions, using cosmic microwave background data from the WMAP satellite. Our search targets a generic set of properties associated with a bubble-collision spacetime, which we describe in detail. We use a modular algorithm that is designed to avoid a posteriori selection effects, automatically picking out the most promising signals, performing a search for causal boundaries, and conducting a full Bayesian parameter estimation and model selection analysis. We outline each component of this algorithm, describing its response to simulated CMB skies with and without bubble collisions. Comparing the results for simulated bubble collisions to the results from an analysis of the WMAP 7-year data, we rule out bubble collisions over a range of parameter space. Our model selection results based on WMAP 7-year data do not warrant augmenting $\Lambda \mathrm{CDM}$ with bubble collisions. Data from the Planck satellite can be used to more definitively test the bubble-collision hypothesis.

It was proposed that the massive compact halo objects (MCHOs) would be produced during an earlier epoch of cosmology if the density perturbations are between $3\times {10}^{-4}$ and 0.3. Then these objects can accrete dark matter particles onto them due to their high density. If the dark matter is in the form of the weakly interacting massive particles, the MCHOs can have a significant effect on the evolution of cosmology due to the dark matter annihilation within them. Using the WMAP-7 years data, we investigated the constraints on the current abundance of MCHOs ($f_{\mathrm{MCHOs}}$) formed during the $e^{+}{e}^{-}$ annihilation phase transition. We have found that the $2\sigma$ constraint is $f_{\mathrm{MCHOs}}\lesssim {10}^{-4}$ for dark matter masses in the range between 1 GeV and 1 TeV.

We reinvestigate the constraints from primordial nucleosynthesis on a possible time-dependent quark mass. The limits on such quark-mass variations are particularly sensitive to the adopted observational abundance constraints. Hence, in the present study we have considered updated light-element abundances and uncertainties deduced from observations. We also consider new nuclear reaction rates and an independent analysis of the influence of such quark-mass variations on the resonance properties of the important ${}^3\mathrm{He}(d,p){}^4\mathrm{He}$ reaction. We find that the updated abundance and resonance constraints imply a narrower range on the possible quark-mass variations in the early universe. We also find that, contrary to previous investigations, the optimum concordance region reduces to a (95% C.L.) value of $-0.005\lesssim \delta m_q/m_q\lesssim 0.007$ consistent with no variation in the averaged quark mass.

Several authors have pointed out that the scalar-mediated interaction of neutrinos in a neutrinophilic two-Higgs-doublet model can be as strong as an electromagnetic interaction [M. Sher and C. Triola, Phys. Rev. D 83, 117702 (2011)][F. Wang, W. Wang, and J. M. Yang, Europhys. Lett. 76, 388 (2006)][S. Gabriel and S. Nandi, Phys. Lett. B 655, 141 (2007)]. We show that the coupling constants of the neutrino-scalar interaction are actually restricted to be $y_i\lesssim 1.5\times {10}^{-3}$ by supernova neutrino observations, and further constrained to be $y_i\lesssim 2.3\times {10}^{-4}$ by precision measurements of acoustic peaks of the cosmic microwave background. Based on the energy-loss argument for supernova cores, we derive a slightly more restrictive bound $y_i\lesssim 3.5\times {10}^{-5}$. Therefore, the neutrinophilic two-Higgs-doublet model has lost its spirit of explaining tiny Dirac neutrino masses while keeping neutrino Yukawa couplings of order one.

We show the potential of the LHC to detect a $CP$-even Higgs boson of the next-to-minimal supersymmetric standard model (NMSSM), $h_1$ or $h_2$, decaying into two rather light $CP$-odd Higgs bosons, $a_1$, by exploiting the production mode based on Higgs-strahlung off $b$-quarks, i.e., the channel $pp\to b\overline{b}{h}_{1,2}$. We also consider the case of $h_2\to h_1{h}_1$ decays. It is found that these decays have dominant BRs over large regions of the NMSSM parameter space where $\tan \beta$ is large, a condition which also favors the $pp\to b\overline{b}{h}_{1,2}$ production rates. Further decays of the light Higgs boson pairs ($a_1$ and $h_1$) into photon, muon, tau, and $b$ final states are also considered. The overall production and decay rates for these processes at inclusive level are sizable and should help extracting at least one Higgs boson signal over the NMSSM parameter space.

We perform a detailed analysis of all existing data (CELLO, CLEO, BABAR) on the pion-photon transition form factor by means of light-cone sum rules in which we include the next-to-leading order QCD radiative corrections and the twist-four contributions. The next-to-next-to-leading order radiative correction together with the twist-six contribution are also taken into account in terms of theoretical uncertainties. Keeping only the first two Gegenbauer coefficients $a_2$ and $a_4$, we show that the $1\sigma$ error ellipse of all data up to $9{\mathrm{GeV}}^2$ greatly overlaps with the set of pion distribution amplitudes obtained from nonlocal QCD sum rules—within the range of uncertainties due to twist-four. This remains valid also for the projection of the $1\sigma$ error ellipsoid on the $(a_2,a_4)$ plane when including $a_6$. We argue that it is not possible to accommodate the high-$Q^2$ tail of the BABAR data with the same accuracy, despite opposite claims by other authors, and conclude that the BABAR data still pose a challenge to QCD.

We study hadronic decays of mesons and baryons in the context of the Dyson-Schwinger equations of QCD. Starting from a well-established effective interaction in rainbow-ladder truncation, we consistently calculate all ingredients of the appropriate decay diagrams. The resulting strong couplings are presented as functions of the quark mass from the chiral limit up to the respective decay thresholds. In particular, we investigate the $\rho \to \pi \pi$ and for the first time the $\Delta \to N\pi$ transitions. Both meson and baryon results compare well to available lattice QCD results as well as experimental data and present the first step towards a comprehensive covariant study of hadron resonances in the Dyson-Schwinger approach.

We construct an effective chiral Lagrangian for hadrons implemented by the conformal invariance and discuss the properties of nuclear matter at high density. The model is formulated based on two alternative assignment, “naive” and mirror, of chirality to the nucleons. It is shown that taking the dilaton limit, in which the mended symmetry of Weinberg is manifest, the vector-meson Yukawa coupling becomes suppressed and the symmetry energy becomes softer as one approaches the chiral phase transition. This leads to softer equations of state (EoS) and could accommodate the EoS without any exotica consistent with the recent measurement of a $1.97\pm 0.04M_{\odot }$ neutron star.

We study the $\sin 2\varphi$ azimuthal asymmetry in the $\pi N$ Drell-Yan process, when the nucleon is longitudinally polarized. The asymmetry is contributed by the combination of the Boer-Mulders function and the longitudinal transversity distribution function. We consider the Drell-Yan processes by ${\pi }^{\pm }$ beams colliding on the proton and deuteron targets, respectively. We calculate the $\sin 2\varphi$ azimuthal asymmetries in these processes using the Boer-Mulders function and the longitudinal transversity from spectator models. We show that the study on single polarized $\pi N$ Drell-Yan processes can not only give the information on the new three-dimensional parton distribution functions in momentum space but also shed light on the chiral-odd structure of the longitudinally polarized nucleon.