Upcoming imaging surveys such as the Large Synoptic Survey Telescope will repeatedly scan large areas of sky and have the potential to yield million-supernova catalogs. Type Ia supernovae are excellent standard candles and will provide distance measures that suffice to detect mean pairwise velocities of their host galaxies. We show that when combining these distance measures with photometric redshifts for either the supernovae or their host galaxies, the mean pairwise velocities of the host galaxies will provide a dark energy probe which is competitive with other widely discussed methods. Adding information from this test to type Ia supernova photometric luminosity distances from the same experiment, plus the cosmic microwave background power spectrum from the Planck satellite, improves the Dark Energy Task Force figure of merit by a factor of 1.8. Pairwise velocity measurements require no additional observational effort beyond that required to perform the traditional supernova luminosity distance test, but may provide complementary constraints on dark energy parameters and the nature of gravity. Incorporating additional spectroscopic redshift follow-up observations could provide important dark energy constraints from pairwise velocities alone. Mean pairwise velocities are much less sensitive to systematic redshift errors than the luminosity distance test or weak lensing techniques, and also are only mildly affected by systematic evolution of supernova luminosity.

We analyze three different new physics scenarios for $\Delta F=2$ flavor-changing neutral currents in the quark sector in the light of recent data on neutral-meson mixing. We parametrize generic new physics contributions to $B_q\mathrm{\text{−}}{\overline{B}}_q$ mixing, $q=d$, $s$, in terms of one complex quantity ${\Delta }_q$, while three parameters ${\Delta }_K^{tt}$, ${\Delta }_K^{ct}$, and ${\Delta }_K^{cc}$ are needed to describe $K\mathrm{\text{−}}\overline{K}$ mixing. In scenario I, we consider uncorrelated new physics contributions in the $B_d$, $B_s$, and $K$ sectors. In this scenario, it is only possible to constrain the parameters ${\Delta }_d$ and ${\Delta }_s$ whereas there are no nontrivial constraints on the kaon parameters. In scenario II, we study the case of minimal flavor violation (MFV) and small bottom Yukawa coupling, where $\Delta \equiv {\Delta }_d={\Delta }_s={\Delta }_K^{tt}$. We show that $\Delta$ must then be real, so that no new $CP$ phases can be accommodated, and express the remaining parameters ${\Delta }_K^{cc}$ and ${\Delta }_K^{ct}$ in terms of $\Delta$ in this scenario. Scenario III is the generic MFV case with large bottom Yukawa couplings. In this case, the kaon sector is uncorrelated to the $B_d$ and $B_s$ sectors. As in the second scenario one has ${\Delta }_d={\Delta }_s\equiv \Delta$, however, now with a complex parameter $\Delta$. Our quantitative analyses consist of global Cabibbo-Kobayashi-Maskawa (CKM) fits within the Rfit frequentist statistical approach, determining the standard model parameters and the new physics parameters of the studied scenarios simultaneously. We find that the recent measurements indicating discrepancies with the standard model are well accommodated in Scenarios I and III with new mixing phases, with a slight preference for Scenario I that permits different new $CP$ phases in the $B_d$ and $B_s$ systems. Within our statistical framework, we find evidence of new physics in both $B_d$ and $B_s$ systems. The standard model hypothesis ${\Delta }_d={\Delta }_s=1$ is disfavored with $p$-values of $3.6\sigma$ and $3.3\sigma$ in Scenarios I and III, respectively. We also present an exhaustive list of numerical predictions in each scenario. In particular, we predict the $CP$ phase in $B_s\to J/\psi \varphi$ and the difference between the $B_s$ and $B_d$ semileptonic asymmetries, which will be both measured by the LHCb experiment.

The different scenarios of spontaneous breaking of $D$ parity have been studied in both the nonsupersymmetric and the supersymmetric version of the left-right symmetric models (LRSM). We explore the possibility of a TeV scale $SU(2{)}_R$ breaking scale $M_R$ and hence TeV scale right-handed neutrinos from both minimization of the scalar potential as well as the coupling constant unification point of view. We show that, although minimization of the scalar potential allows the possibility of a TeV scale $M_R$ and tiny neutrino masses in LRSM with spontaneous $D$-parity breaking, the gauge coupling unification at a high scale $\sim {10}^{16}\mathrm{GeV}$ does not favor a TeV scale symmetry breaking except in the supersymmetric left-right model with Higgs doublet and bidoublet. The phenomenology of neutrino mass is also discussed.

We perform a model study of deconfinement and chiral symmetry restoration in a strong magnetic background. We use a Nambu–Jona-Lasinio model with the Polyakov loop, taking into account a possible dependence of the coupling on the Polyakov-loop expectation value, as suggested by the recent literature. Our main result is that, within this model, the deconfinement and chiral crossovers of QCD in strong magnetic field are entangled even at the largest value of $eB$ considered here, namely $eB=30m_{\pi }^2$ (that is, $B\approx 6\times {10}^{15}\mathrm{T}$). The amount of split that we measure is, at this value of $eB$, of the order of 2%. We also study briefly the role of the 8-quark term on the entanglement of the two crossovers. We then compare the phase diagram of this model with previous results, as well as with available lattice data.

We present measurements of partial branching fractions of $B\to K^{+}X$, $B\to K^{0}X$, and $B\to {\pi }^{+}X$, where $X$ denotes any accessible final state above the endpoint for $B$ decays to charmed mesons, specifically for momenta of the candidate hadron greater than 2.34 (2.36) GeV for kaons (pions) in the $B$ rest frame. These measurements are sensitive to potential new-physics particles which could enter the $b\to s(d)$ loop transitions. The analysis is performed on a data sample consisting of $383\times {10}^{6}B\overline{B}$ pairs collected with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ asymmetric energy collider. We observe the inclusive $B\to {\pi }^{+}X$ process, and we set upper limits for $B\to K^{+}X$ and $B\to K^{0}X$. Our results for these inclusive branching fractions are consistent with those of known exclusive modes, and exclude large enhancements due to sources of new physics.

In the context of Born-Infeld electrodynamics, the electromagnetic fields interact with each other via their nonlinear couplings. A calculation will be performed where an incoming electromagnetic plane wave scatters off a Coulomb field in the geometrical optics approximation. In addition to finding the first-order angle of deflection, exact solutions for the trajectory will also be found. The possibility of electromagnetic bound states will be discussed.

In this paper, we consider two different issues, stability and strong coupling, which have been raised recently in the newly proposed Horava-Lifshitz theory of quantum gravity with the projectability condition. We find that all the scalar modes are stable in the de Sitter background, due to two different kinds of effects, one from high-order derivatives of the spacetime curvature and the other from the exponential expansion of the de Sitter space. Combining these effects properly, one can make the instability found in the Minkowski background never appear even for small-scale modes, provided that the IR limit is sufficiently close to the relativistic fixed point. At the fixed point, all the modes become stabilized. We also show that the instability of Minkowski spacetime can be cured by introducing mass to the spin-0 graviton. The strong coupling problem is investigated following the effective field theory approach, and we find that it cannot be cured by the Blas-Pujolas-Sibiryakov mechanism, initially designed for the case without the projectability condition, but might be circumvented by the Vainshtein mechanism, due to the nonlinear effects. In fact, we construct a class of exact solutions, and show explicitly that they reduce smoothly to the de Sitter spacetime in the relativistic limit.

We study geometric structures associated with shear-free null geodesic congruences in Minkowski space-time and asymptotically shear-free null geodesic congruences in asymptotically flat space-times. We show how in both the flat and asymptotically flat settings, complexified future null infinity ${\mathfrak{I}}_{\mathbb{C}}^{+}$ acts as a “holographic screen,” interpolating between two dual descriptions of the null geodesic congruence. One description constructs a complex null geodesic congruence in a complex space-time whose source is a complex worldline, a virtual source as viewed from the holographic screen. This complex null geodesic congruence intersects the real asymptotic boundary when its source lies on a particular open-string type structure in the complex space-time. The other description constructs a real, twisting, shear-free or asymptotically shear-free null geodesic congruence in the real space-time, whose source (at least in Minkowski space) is in general a closed-string structure: the caustic set of the congruence. Finally we show that virtually all of the interior space-time physical quantities that are identified at null infinity ${\mathfrak{I}}^{+}$ (center of mass, spin, angular momentum, linear momentum, and force) are given kinematic meaning and dynamical descriptions in terms of the complex worldline.

We consider the polymer quantization of the Einstein wormhole throat theory for an eternal Schwarzschild black hole. We numerically solve the difference equation describing the quantum evolution of an initially Gaussian, semiclassical wave packet. As expected from previous work on loop quantum cosmology, the wave packet remains semiclassical until it nears the classical singularity at which point it enters a quantum regime in which the fluctuations become large. The expectation value of the radius reaches a minimum as the wave packet is reflected from the origin and emerges to form a near-Gaussian but asymmetrical semiclassical state at late times. The value of the minimum depends in a nontrivial way on the initial mass/energy of the pulse, its width, and the polymerization scale. For wave packets that are sufficiently narrow near the bounce, the semiclassical bounce radius is obtained. Although the numerics become difficult to control in this limit, we argue that for pulses of finite width the bounce persists as the polymerization scale goes to zero, suggesting that in this model the loop quantum gravity effects mimicked by polymer quantization do not play a crucial role in the quantum bounce.

We analyze decay processes of the inflaton field, $\varphi$, during the coherent oscillation phase after inflation in $f(\varphi )R$ gravity. It is inevitable that the inflaton decays gravitationally into gauge fields in the presence of $f(\varphi )R$ coupling. We show a concrete calculation of the rate that the inflaton field decays into a pair of gauge fields via the trace anomaly. Comparing this new decay channel via the anomaly with the channels from the tree-level analysis, we find that the branching ratio crucially depends on masses and the internal multiplicities (flavor quantum number) of decay product particles. While the inflaton decays exclusively into light fields, heavy fields still play a role in quantum loops. We argue that this process in principle allows us to constrain the effects of arbitrary heavy particles in the reheating. We also apply our analysis to Higgs inflation, and find that the gravitational decay rate would never exceed gauge interaction decay rates if quantum gravity is unimportant.

We point out that the non-Gaussianity arising from cubic self-interactions of the inflaton field is proportional to $\xi N_e$ where $\xi \sim V^{\prime \prime \prime }$ and $N_e$ is the number of $e$-foldings from horizon exit till the end of inflation. For scales of interest $N_e=60$, and for models of inflation such as new inflation, natural inflation, and running mass inflation $\xi$ is large compared to the slow-roll parameter $ϵ\sim V^{\prime 2}$. Therefore, the contribution from self-interactions should not be outrightly ignored while retaining other terms in the non-Gaussianity parameter $f_{\mathrm{NL}}$. However, the $N_e$-dependent term seems to imply the growth of non-Gaussianities outside the horizon. Therefore, we briefly discuss the issue of the constancy of correlations of the curvature perturbation $\zeta$ outside the horizon. We then calculate the 3-point function of the inflaton fluctuations using the canonical formalism and further obtain the 3-point function of ${\zeta }_k$. We find that the $N_e$-dependent contribution to $f_{\mathrm{NL}}$ from self-interactions of the inflaton field is canceled by contributions from other terms associated with nonlinearities in cosmological perturbation theory.

We discuss models of primordial density perturbations where the non-Gaussianity is strongly scale dependent. In particular, the non-Gaussianity may have a sharp cutoff and be very suppressed on large cosmological scales, but sizable on small scales. This may have an impact on probes of non-Gaussianity in the large-scale structure and in the cosmic microwave background radiation anisotropies.

Within the framework of the nonrelativistic QCD factorization approach, we compute the cross section and polarization of prompt $J/\psi$ produced from proton-proton collisions at the center-of-momentum energy $\sqrt{s}=200\mathrm{GeV}$. We present the transverse-momentum distribution in the forward-rapidity region $1.2<|y|<2.2$ and the rapidity distribution over the transverse-momentum range $2\mathrm{GeV}<p_T<20\mathrm{GeV}$. The perturbative contributions are computed at leading order in the strong coupling constant. We predict slight transverse polarization of $J/\psi$ in the forward-rapidity region, while that for the midrapidity region is slightly longitudinal. The transverse-momentum distribution agrees well with the PHENIX preliminary data and the color-singlet-model prediction at next-to-leading order in ${\alpha }_s$, but disagrees with the result from the leading-order color-singlet model or the $s$-channel-cut method.

Recently, the D0 Collaboration reported a large $CP$ violation in the same-sign dimuon charge asymmetry which has the $3.2\sigma$ deviation from the value estimated in the standard model. In this paper, several new physics models are considered: the minimal supersymmetric standard model, the two Higgs doublet model, the recent dodeca model, and a new $Z^{\prime }$ model. Generally, it is hard to achieve such a large $CP$ violation consistently with other experimental constraints. We find that a scheme with extra nonanomalous $\mathrm{U}(1{)}^{\prime }$ gauge symmetry is barely consistent. In general, the extra $Z^{\prime }$ gauge boson induces the flavor changing neutral current interactions at tree level, which is the basic reason for allowing a large new physics $CP$ violation. To preserve the $\mathrm{U}(1{)}^{\prime }$ symmetry at high energy, $\mathrm{SU}(2{)}_L$ singlet exotic heavy quarks of mass above 1 TeV and the standard model gauge singlet scalars are introduced.

We present a reduction method for Wilson-Dirac fermions with nonzero chemical potential which generates a dimensionally reduced fermion matrix. The size of the reduced fermion matrix is independent of the temporal lattice extent and the dependence on the chemical potential is factored out. As a consequence the reduced matrix allows a simple evaluation of the Wilson fermion determinant for any value of the chemical potential and hence the exact projection to the canonical partition functions.

The nonlinear evolution equation at small $x$ with impact parameter dependence is analyzed numerically. The saturation scales and the radius of expansion in the impact parameter are extracted as functions of rapidity. Running coupling is included in this evolution, and it is found that the solution is sensitive to the infrared regularization. Kinematical effects beyond the leading logarithmic approximation are taken partially into account by modifying the kernel which includes the rapidity-dependent cuts. These effects are important for the nonlinear evolution with the impact parameter dependence.

A new type of parametrization for parton distribution functions, based on their $Q^2$-evolution at large and small $x$ values, is constructed for valence quarks. It obeys exactly the Gross-Llewellyn-Smith sum rule.

The effects of intermediate charmed mesons on charmonium transitions with the emission of one pion or eta are studied systematically. Based on a nonrelativistic effective field theory we show that charmed meson loops are enhanced compared to the corresponding tree-level contributions for transitions between two $S$-wave charmonia as well as for transitions between two $P$-wave charmonia. On the contrary, for the transitions between one $S$-wave and one $P$-wave charmonium state, the loops need to be analyzed case by case and often appear to be suppressed. The relation to and possible implications for an effective Lagrangian approach are also discussed. This study at the same time provides a cross-check for the numerical evaluations.

The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with $t\overline{t}$ and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are roadblocks to a direct computation with the Britto-Cachazo-Feng-Witten method. We evade these by using an auxiliary scalar theory to compute a subset of the amplitudes.

We discuss a neutrino mass model based on the $S_4$ discrete symmetry where the symmetry breaking is triggered by the boundary conditions of the bulk right-handed neutrino in the fifth spacial dimension. The three generations of the left-handed lepton doublets and the right-handed neutrinos are assigned to be the triplets of $S_4$. The magnitudes of the lepton mixing angles, especially the reactor angle, are related to the neutrino mass patterns, and the model will be tested in future neutrino experiments, e.g., an early discovery of the reactor angle favors the normal hierarchy. For the inverted hierarchy, the lepton mixing is predicted to be almost the tribimaximal mixing. The size of the extra dimension has a connection to the possible mass spectrum; a small (large) volume corresponds to the normal (inverted) mass hierarchy.