We examine gravitational wave memory in the case where sources and detector are in an expanding cosmology. For simplicity, we treat the case where the cosmology is de Sitter spacetime, and discuss the possibility of generalizing our results to the case of a more realistic cosmology. We find results very similar to those of gravitational wave memory in an asymptotically flat spacetime, but with the magnitude of the effect multiplied by a redshift factor.

Gamma-ray experiments seeking to detect evidence of dark matter annihilation in dwarf spheroidal galaxies require knowledge of the distribution of dark matter within these systems. We analyze the effects of flattening on the annihilation (J) and decay (D) factors of dwarf spheroidal galaxies with both analytic and numerical methods. Flattening has two consequences: first, there is a geometric effect as the squeezing (or stretching) of the dark matter distribution enhances (or diminishes) the J-factor; second, the line of sight velocity dispersion of stars must hold up the flattened baryonic component in the flattened dark matter halo. We provide analytic formulas and a simple numerical approach to estimate the correction to the J- and D-factors required over simple spherical modeling. The formulas are validated with a series of equilibrium models of flattened stellar distributions embedded in flattened dark-matter distributions. We compute corrections to the J- and D-factors for the Milky Way dwarf spheroidal galaxies under the assumption that they are all prolate or all oblate and find that the hierarchy of J-factors for the dwarf spheroidals is slightly altered (typical correction factors for an ellipticity of 0.4 are 0.75 for the oblate case and 1.6 for the prolate case). We demonstrate that spherical estimates of the D-factors are very insensitive to the flattening and introduce uncertainties significantly less than the uncertainties in the D-factors from the other observables for all the dwarf spheroidals (for example, $\genfrac{}{}{0ex}{}{+10\text{per cent}}{-3\text{per cent}}$ for a typical ellipticity of 0.4). We conclude by investigating the spread in correction factors produced by triaxial figures and provide uncertainties in the J-factors for the dwarf spheroidals using different physically motivated assumptions for their intrinsic shape and axis alignments. We find that the uncertainty in the J-factors due to triaxiality increases with the observed ellipticity and, in general, introduces uncertainties of a factor of 2 in the J-factors. We discuss our results in light of the reported gamma-ray signal from the highly flattened ultrafaint Reticulum II. Tables of the J- and D-factors for the Milky Way dwarf spheroidal galaxies are provided (assuming an oblate or prolate structure) along with a table of the uncertainty on these factors arising from the unknown triaxiality.

We present an application of large deviation theory to the problem of structure growth on large scale structure cosmology. Starting from Gaussian distributed overdensities on concentric spherical shells, we show that a large deviation principle holds for the densities on the corresponding shells after gravitational evolution if no shell crossing happens. As consequences of the large deviation principle we obtain the cumulant-generating function for the nonlinear densities, and present formulas to compute the cumulant-generating function for general window functions.

Large-angle fluctuations in the cosmic microwave background temperature induced by the integrated Sachs-Wolfe effect and Compton-$y$ distortions from the thermal Sunyaev-Zeldovich (tSZ) effect are both due to line-of-sight density perturbations. Here we calculate the cross-correlation between these two signals. Measurement of this cross-correlation can be used to test the redshift distribution of the tSZ distortion, which has implications for the redshift at which astrophysical processes in clusters begin to operate. We also evaluate the detectability of a $yT$ cross-correlation from exotic early-Universe sources in the presence of this late-time effect.

A new family of inflationary models is introduced and analyzed. The behavior of the parameters characterizing the models suggest preferred values, which generate the most interesting testable predictions. Results are further improved if late reheating and/or a subsequent period of thermal inflation is taken into account. Specific model realizations consider a sub-Planckian inflaton variation or a potential without fine-tuning of mass scales, based on the Planck and grand unified theory scales. A toy model realization in the context of global and local supersymmetry is examined, and results fitting the Planck observations are determined.

Very long and precise follow-up measurements of the x-ray afterglow of very intense gamma-ray bursts (GRBs) allow a critical test of GRB theories. Here we show that the single power-law decay with time of the x-ray afterglow of GRB 130427A, the record-long and most accurately measured x-ray afterglow of an intense GRB by the Swift, Chandra, and XMM-Newton space observatories, and of all other known intense GRBs, is that predicted by the cannonball model of GRBs from their measured spectral index, while it disagrees with that predicted by the widely accepted fireball models of GRBs.

Gravitational waves propagating through a stationary gauge field transform into gauge field waves and back again. When multiple families of flavor-space locked gauge fields are present, the gravitational and gauge field waves exhibit novel dynamics. At high frequencies, the system behaves like coupled oscillators in which the gravitational wave is the central pacemaker. Due to energy conservation and exchange among the oscillators, the wave amplitudes lie on a multidimensional sphere, reminiscent of neutrino flavor oscillations. This phenomenon has implications for cosmological scenarios based on flavor-space locked gauge fields.

Effective field theories have often been applied to systems with deeply inelastic reactions that produce particles with large momenta outside the domain of validity of the effective theory. The effects of the deeply inelastic reactions have been taken into account in previous work by adding local anti-Hermitian terms to the effective Hamiltonian. Here, we show that when multiparticle systems are considered, an additional modification is required in equations governing the density matrix. We define an effective density matrix by tracing over the states containing high-momentum particles and show that it satisfies a Lindblad equation, with local Lindblad operators determined by the anti-Hermitian terms in the effective Hamiltonian density.

We determine the effect of a $CPT$-even and Lorentz violating nonminimal coupling on the differential cross sections for some of the most important tree-level processes in QED, namely, Compton and Bhabha scatterings, as well as electron-positron annihilation. Experimental limits constraining the allowed deviation of the differential cross sections relative to pure QED allow us to place upper bounds on the Lorentz violating parameters. A constraint based on the decay rate of parapositronium is also obtained.

Motivated by the recent CMS excess in a flavor violating Higgs decay $h\to \mu \tau$ as well as the anomaly of muon anomalous magnetic moment (muon $g-2$), we consider a scenario where both the excess in $h\to \mu \tau$ and the anomaly of muon $g-2$ are explained by the $\mu -\tau$ flavor violation in a general two Higgs doublet model. We study various processes involving $\mu$ and $\tau$, and then discuss the typical predictions and constraints in this scenario. Especially, we find that the prediction of $\tau \to \mu \gamma$ can be within the reach of the Belle II experiment. We also show that the lepton nonuniversality between $\tau \to \mu \nu \overline{\nu }$ and $\tau \to e\nu \overline{\nu }$ can be sizable, and hence the analysis of the current Belle data and the future experimental improvement would have an impact on this model. Besides, processes such as $\tau \to \mu l^{+}{l}^{-}$ $(l=e,\mu )$, $\tau \to \mu \eta$, $\mu \to e\gamma$, $\mu \to 3e$, and the muon electric dipole moment can be accessible, depending on the unknown Yukawa couplings. On the other hand, the processes like $\tau \to e\gamma$ and $\tau \to e{l}^{+}{l}^{-}$ $(l=e,\mu )$ could not be sizable to observe because of the current strong constraints on the $e-\mu$ and $e-\tau$ flavor violations. Then we also conclude that contrary to the $h\to \mu \tau$ decay mode, the lepton flavor violating Higgs boson decay modes $h\to e\mu$ and $h\to e\tau$ are strongly suppressed, and hence it will be difficult to observe these modes at the LHC experiment.

We show that when a dark Abelian gauge sector and $\mathrm{SU}(2{)}_L$ kinetically mix it necessarily generates a relation between the kinetic mixing strength and the mass of the mediating particle. Remarkably, this correspondence maps the weak scale directly to the kinetic mixing strengths being probed by modern fixed-target experiments and next generation flavor factories. This illuminates the exciting possibility of correlated discoveries of a new particle at the LHC and a dark photon at intensity frontier experiments. To motivate the scenario, we construct a simple model and explore its phenomenology and constraints.

We calculate charmonium correlators on the lattice with $2+1$ flavors of sea quarks and charm valence quarks, both described by the Möbius domain-wall fermion. Temporal moments of the correlators are calculated and matched to perturbative QCD formulas to extract the charm quark mass $m_c(\mu )$ and strong coupling constant ${\alpha }_s(\mu )$. Lattice data at three lattice spacings, 0.044, 0.055, and 0.080 fm, are extrapolated to the continuum limit. The correlators in the vector channel are confirmed to be consistent with the experimental data for $e^{+}{e}^{-}\to c\overline{c}$, while the pseudoscalar channel is used to extract $m_c(\mu )$ and ${\alpha }_s(\mu )$. We obtain $m_{\mathrm{c}}(3\mathrm{GeV})=1.003(10)\mathrm{GeV}$ and ${\alpha }_s^{\overline{\mathrm{MS}}(4)}(3\mathrm{GeV})=0.253(13)$. The dominant source of the error is the truncation of perturbative expansion at ${\alpha }_s^3$.

In the present work we study production of $J/\psi +{\chi }_c$ and $J/\psi +J/\psi$ at the LHC. The first process is forbidden at the leading order in gluon fusion due to the $C$-parity conservation, and the first nonvanishing contribution is given by the process with the additional emission of a real gluon. Considering the direct production of $J/\psi +J/\psi$, where the leading order is allowed, we have found that the contribution from the higher order process with real gluon emission is comparable and even more significant than the leading order. Moreover, account of this higher order effect dramatically changes kinematical distributions. Through the present paper we study in detail different channels of paired $J/\psi +J/\psi$ production: direct $J/\psi +J/\psi$ production, feed-down from the $J/\psi +{\chi }_c$ channel, and double parton scattering. We also try to find kinematical distributions that are most suitable to separate these different channels.

The one-loop QCD corrections to the light-front wave function for the quark-antiquark Fock state inside a transverse or longitudinal off-shell photon are explicitly calculated, both in full momentum space and in mixed space (also known as dipole space). These results provide one of the main contributions to virtual next-to-leading-order (NLO) corrections to many deep inelastic scattering (DIS) observables (inclusive or not) in the dipole factorization formalism at low Bjorken $x$. In a follow-up article, these one-loop corrections are combined with earlier results on the wave function for the quark-antiquark-gluon Fock state, in order to get the full set of NLO corrections to the DIS structure functions $F_2$ and $F_L$ in the dipole factorization formalism, valid at low Bjorken $x$.

A simultaneous electroweak and QCD fit of electroweak parameters and parton distribution functions to HERA data on deep inelastic scattering is presented. The input data are neutral current and charged current inclusive cross sections measured by the H1 and ZEUS collaborations at the $ep$ collider HERA. The polarization of the electron beam was taken into account for the ZEUS and H1 data recorded between 2004 and 2007. Results are presented on the vector and axial-vector couplings of the $Z$ boson to $u$- and $d$-type quarks. The values are in agreement with Standard Model predictions. The results on $a_u$ and $v_u$ represent the most precise measurements from a single process.

The holographic quantum entanglement entropy for an infinite strip region of the boundary for the field theory dual to charged black holes in $\mathcal{A}d{S}_{3+1}$ is investigated. In this framework we elucidate the low and high temperature behavior of the entanglement entropy pertaining to various limits of the black hole charge. In the low temperature regime we establish a first law of entanglement thermodynamics for the boundary field theory.

For a boundary conformal field theory to give a good approximation to the bulk flat-space $S$-matrix, a number of conditions need to be satisfied: some of those are investigated here. In particular, one would like to identify an appropriate set of approximate asymptotic scattering states, constructed purely via boundary data. We overview, elaborate, and simplify obstacles encountered with existing proposals for these. Those corresponding to normalizable wave functions undergo multiple interactions; we contrast this situation with that needed for a flat-space Lehmann-Symanzik-Zimmermann treatment. Non-normalizable wave functions can have spurious interactions, due either to power-law tails of wave packets or to their non-normalizable behavior, which obscure $S$-matrix amplitudes we wish to extract, although in the latter case we show that such gravitational interactions can be finite, as a result of gravitational redshift. We outline an illustrative construction of arbitrary normalizable wave packets from boundary data that also yields such spurious interactions. Another set of nontrivial questions regard the form of unitarity relations for the bulk $S$-matrix, and in particular its normalization and multiparticle cuts. These combined constraints, together with those found earlier on a boundary singularity structure needed for bulk momentum conservation and other physical/analytic properties, are a nontrivial collection of obstacles to surmount if a fine-grained $S$-matrix, as opposed to a coarse-grained construction, is to be defined purely from boundary data.

We study the boundary conditions in topologically twisted Chern-Simons matter theories with the Lie 3-algebraic structure. We find that the supersymmetric boundary conditions and the gauge-invariant boundary conditions can be unified as complexified gauge-invariant boundary conditions which lead to supergroup Wess-Zumino-Witten (WZW) models. We propose that the low-energy effective field theories on the two-dimensional intersection of multiple M2-branes on a holomorphic curve inside K3 with two nonparallel M5-branes on the K3 are supergroup WZW models from the topologically twisted Bagger-Lambert-Gustavson model and the Aharony-Bergman-Jafferis-Maldacena model.

We compute the effective action of the Polyakov loop in $SU(2)$ and $SU(3)$ Yang-Mills theory using a previously developed covariant variational approach. The formalism is extended to background gauge and it is shown how to relate the low-order Green’s functions to the ones in Landau gauge studied earlier. The renormalization procedure is discussed. The self-consistent effective action is derived and evaluated using the numerical solution of the gap equation. We find a clear signal for a deconfinement phase transition at finite temperatures, which is second order for $SU(2)$ and first order for $SU(3)$. The critical temperatures obtained are in reasonable agreement with high-precision lattice data.