The effective low energy Lagrangian of $C{P}^{N-1}$ models in $d<4$ dimensions can be constructed in the large $N$ limit by solving the saddle point equations in the presence of a constant field strength. The two-dimensional case is explicitly worked out, and possible applications are briefly discussed.

In previous works we have studied spin-$3/2$ fields near four-dimensional Schwarzschild black holes. The techniques we developed in that case have now been extended here to show that it is possible to determine the potential of spin-$3/2$ fields near $D$-dimensional black holes by exploiting the radial symmetry of the system. This removes the need to use the Newman-Penrose formalism, which is difficult to extend to $D$-dimensional spacetimes. In this paper we will derive a general $D$-dimensional gauge-invariant effective potential for spin-$3/2$ fields near black hole systems. We then use this potential to determine the quasinormal modes and absorption probabilities of spin-$3/2$ fields near a $D$-dimensional Schwarzschild black hole.

Atom interferometry experiments are searching for evidence of chameleon scalar fields with ever-increasing precision. As experiments become more precise, so too must theoretical predictions. Previous work has made numerous approximations to simplify the calculation, which in general requires solving a three-dimensional nonlinear partial differential equation. This paper calculates the chameleonic force using a numerical relaxation scheme on a uniform grid. This technique is more general than previous work, which assumed spherical symmetry to reduce the partial differential equation to a one-dimensional ordinary differential equation. We examine the effects of approximations made in previous efforts on this subject and calculate the chameleonic force in a setup that closely mimics the recent experiment of Hamilton et al. Specifically, we simulate the vacuum chamber as a cylinder with dimensions matching those of the experiment, taking into account the backreaction of the source mass, its offset from the center, and the effects of the chamber walls. Remarkably, the acceleration on a test atomic particle is found to differ by only 20% from the approximate analytical treatment. These results allow us to place rigorous constraints on the parameter space of chameleon field theories, although ultimately the constraint we find is the same as the one we reported in Hamilton et al. because we had slightly underestimated the size of the vacuum chamber. This computational technique will continue to be useful as experiments become even more precise and will also be a valuable tool in optimizing future searches for chameleon fields and related theories.

Extracting astrophysical information from gravitational-wave detections is a well-posed problem and thoroughly studied when detailed models for the waveforms are available. However, one motivation for the field of gravitational-wave astronomy is the potential for new discoveries. Recognizing and characterizing unanticipated signals requires data analysis techniques which do not depend on theoretical predictions for the gravitational waveform. Past searches for short-duration unmodeled gravitational-wave signals have been hampered by transient noise artifacts, or “glitches,” in the detectors. We have put forth the BayesWave algorithm to differentiate between generic gravitational-wave transients and glitches, and to provide robust waveform reconstruction and characterization of the astrophysical signals. Here we study BayesWave’s capabilities for rejecting glitches while assigning high confidence to detection candidates through analytic approximations to the Bayesian evidence. Analytic results are tested with numerical experiments by adding simulated gravitational-wave transient signals to LIGO data collected between 2009 and 2010 and found to be in good agreement.

As numerical calculations of inspiraling neutron-star binaries reach values of accuracy that are comparable with those of black-hole binaries, a fine budgeting of the various sources of error becomes increasingly important. Among such sources, the initial data are normally not accounted for, the rationale being that the error on the initial spacelike hypersurface is always far smaller than the error gained during the evolution. We here consider critically this assumption and perform a comparative analysis of the gravitational waveforms relative to essentially the same physical binary configuration when computed with two different initial-data codes, and then evolved with the same evolution code. More specifically, we consider the evolution of irrotational neutron-star binaries computed either with the pseudospectral code lorene, or with the newly developed finite-difference code cocal; both sets of initial data are subsequently evolved with the high-order-evolution code whiskythc. In this way we find that although global quantities of the system, like the mass and angular momentum, have differences of the order of $\lesssim 0.02\%$, local quantities, like rest-mass density, extrinsic curvature or angular velocity, show pointwise differences that are much larger, of the order of $\lesssim 1\%$. These local differences are then responsible for a dephasing in the gravitational waves at the merger time (after approximately three orbits) of $\sim 1.4$ radians. Our results highlight the importance of using initial data that are pointwisely the same when comparative studies are done and physical parameters are estimated.

We investigate expected constraints on equilateral-type primordial non-Gaussianities from future/ongoing imaging surveys, making use of the fact that they enhance the halo/galaxy bispectrum on large scales. As model parameters to be constrained, in addition to $f_{\mathrm{NL}}^{\text{equil}}$, which is related to the primordial bispectrum, we consider $g_{\mathrm{NL}}^{(\partial \sigma {)}^4}$, which is related to the primordial trispectrum that appeared in the effective field theory of inflation. After calculating the angular bispectra of the halo/galaxy clustering and weak gravitational lensing based on the integrated perturbation theory, we perform Fisher matrix analysis for three representative surveys. We find that among the three surveys, the tightest constraints come from Large Synoptic Survey Telescope; its expected $1\sigma$ errors on $f_{\mathrm{NL}}^{\text{equil}}$ and $g_{\mathrm{NL}}^{(\partial \sigma {)}^4}$ are respectively given by $7.0\times 10^2$ and $4.9\times 10^7$. Although this constraint is somewhat looser than the one from the current cosmic microwave background observation, since we obtain it independently, we can use this constraint as a cross-check. We also evaluate the uncertainty with our results caused by using several approximations and discuss the possibility to obtain tighter constraint on $f_{\mathrm{NL}}^{\text{equil}}$ and $g_{\mathrm{NL}}^{(\partial \sigma {)}^4}$.

We discuss the cosmological implications of the $R{\square }^{-2}R$ nonlocal modification to standard gravity. We relax the assumption of special initial conditions in the local formulation of the theory, perform a full phase-space analysis of the system, and show that the late-time cosmology of the model exhibits two distinct evolution paths, on which a large range of values for the present equation of state can be reached. We then compare the general solutions to supernovae data and place constraints on the parameters of the model. In particular, we find that the mass parameter of the theory should be smaller than 1.2 in Hubble units.

Theories of massive gravity with one or two dynamical metrics generically lack stable and observationally viable cosmological solutions that are distinguishable from $\mathrm{\Lambda }$ cold dark matter (CDM). We consider an extension to trimetric gravity, with three interacting spin-2 fields which are not plagued by the Boulware-Deser ghost. We systematically explore every combination with two free parameters in search of background cosmologies that are competitive with $\mathrm{\Lambda }\mathrm{CDM}$. For each case we determine whether the expansion history satisfies viability criteria, and whether or not it contains beyond-$\mathrm{\Lambda }\mathrm{CDM}$ phenomenology. Among the many models we consider, there are only three cases that seem to be both viable and distinguishable from standard cosmology. One of the models has only one free parameter and displays a crossing from above to below the phantom divide. The other two provide scaling behavior, although they contain future singularities that need to be studied in more detail. These models possess interesting features that make them compelling targets for a full comparison to observations of both cosmological expansion history and structure formation.

Recent clarifications of naturalness in supersymmetry robustly require the presence of four light Higgsinos with mass $\sim 100–300\mathrm{GeV}$ while gluinos and (top) squarks may lie in the multi-TeV range, possibly out of LHC reach. We project the high-luminosity ($300–3000{\mathrm{fb}}^{-1}$) reach of LHC14 via gluino cascade decays and via same-sign diboson production. We compare these to the reach for neutralino pair production ${\tilde{Z}}_1{\tilde{Z}}_2$ followed by ${\tilde{Z}}_2\to {\tilde{Z}}_1{\ell }^{+}{\ell }^{-}$ decay to soft dileptons which recoil against a hard jet. It appears that $3000{\mathrm{fb}}^{-1}$ is just about enough integrated luminosity to probe naturalness with up to 3% fine-tuning at the $5\sigma$ level, thus either discovering natural supersymmetry or else ruling it out.

Dark matter (DM) in Earth-intersecting orbits can scatter off electrons and lose energy, and be gravitationally bound to the Earth. Eventually, they lose enough energy and accumulate at the core. It is assumed that DM annihilates/decays predominantly into Standard Model particles inside the Earth. The heat flux from these processes is compared with the experimentally measured value of the internal heat flux of the Earth, which is 44 TW. Assuming a steady state between capture and annihilation/decay, we put constraints on the scattering cross section of DM with electrons as a function of their mass. For low-mass regions ($<{10}^{-2}\mathrm{GeV}$), these constraints on leptophilic DM are better than those obtained from direct-detection experiments.

We present a lattice simulation study of large $N_c$ regularities of meson and baryon spectroscopy in $SU(N_c)$ gauge theory with two flavors of dynamical fundamental representation fermions. Systems investigated include $N_c=2$, 3, 4, and 5, over a range of fermion masses parametrized by a squared pseudoscalar to vector meson mass ratio between about 0.2 to 0.7. Good agreement with large $N_c$ scaling is observed in the static potential, in meson masses and decay constants, and in baryon spectroscopy.

In the perturbative QCD (PQCD) approach, we study the direct $CP$ violation in the decay processes of $B_c^{+}\to D_{(s)}^{+}{\rho }^0(\omega )\to D_{(s)}^{+}{\pi }^{+}{\pi }^{-}$ via the $\rho -\omega$ mixing mechanism. We find that the $CP$ violation can be enhanced by $\rho -\omega$ mixing when the invariant masses of the ${\pi }^{+}{\pi }^{-}$ pairs are in the vicinity of the $\omega$ resonance. For the decay process of $B_c^{+}\to D^{+}{\rho }^0(\omega )\to D^{+}{\pi }^{+}{\pi }^{-}$, the maximum $CP$ violation can reach 7.33%.

Starting from a textbook result, the nearest-neighbor distribution of particles in an ideal gas, we develop estimates for the probability with which quarks $q$ in a mixed $q$, $\overline{q}$ gas are more strongly attracted to the nearest $q$, potentially forming a diquark, than to the nearest $\overline{q}$. Generic probabilities lie in the range of tens of percent, with values in the several percent range even under extreme assumptions favoring $q\overline{q}$ over $qq$ attraction.

We consider the production of a heavy neutrino and its possible signals at the Large Hadron-electron Collider (LHeC) in the context of an inverse-seesaw model for neutrino mass generation. The inverse seesaw model extends the Standard Model (SM) particle content by adding two neutral singlet fermions for each lepton generation. It is a well-motivated model in the context of generating nonzero neutrino masses and mixings. The proposed future LHeC machine presents us with a particularly interesting possibility to probe such extensions of the SM with new leptons due to the presence of an electron beam in the initial state. We show that the LHeC will be able to probe an inverse scenario with much better efficacy compared to the LHC with very nominal integrated luminosities as well as exploit the advantage of having the electron beam polarized to enhance the heavy neutrino production rates.

We investigate a holographic model of superfluid flows with an external repulsive potential. When the strength of the potential is sufficiently weak, we analytically construct two steady superfluid flow solutions. As the strength of the potential is increased, the two solutions merge into a single critical solution at a critical strength, and then disappear above the critical value, as predicted by a saddle-node bifurcation theory. We also analyze the spectral function of fluctuations around the solutions under a certain decoupling approximation.

We discuss the renormalization of the initial value problem in nonequilibrium quantum field theory within a simple, yet instructive, example and show how to obtain a renormalized time evolution for the two-point functions of a scalar field and its conjugate momentum at all times. The scheme we propose is applicable to systems that are initially far from equilibrium and compatible with nonsecular approximation schemes which capture thermalization. It is based on Kadanoff-Baym equations for non-Gaussian initial states, complemented by usual vacuum counterterms. We explicitly demonstrate how various cutoff-dependent effects peculiar to nonequilibrium systems, including time-dependent divergences or initial-time singularities, are avoided by taking an initial non-Gaussian three-point vacuum correlation into account.

We present new soliton and hairy black hole solutions of Einstein–non-Abelian–Proca theory in asymptotically anti–de Sitter spacetime with gauge group $\mathfrak{su}(2)$. For static, spherically symmetric configurations, we show that the gauge field must be purely magnetic, and we solve the resulting field equations numerically. The equilibrium gauge field is described by a single function $\omega (r)$, which must have at least one zero. The solitons and hairy black holes share many properties with the corresponding solutions in asymptotically flat spacetime. In particular, all the solutions we study are unstable under linear, spherically symmetric, perturbations of the metric and gauge field.

The typical motions of a spinning test particle in Schwarzschild’s background which show the strong repulsive action of the highly relativistic spin-gravity coupling are considered using the exact Mathisson-Papapetrou equations. An approximated approach to choice solutions of these equations which describe motions of the particle’s proper center of mass is developed.

We perform an analysis of the Einstein-Skyrme cosmological model in the Bianchi-IX background. We analytically describe asymptotic regimes and semianalytically describe generic regimes. It appears that depending on the product of the Newtonian constant $\kappa$ with Skyrme coupling $K$, in the absence of the cosmological term, there are three possible regimes: recollapse with $\kappa K<2$ and two power-law regimes, $\propto t^{1/2}$ for $\kappa K=2$ and $\propto t$ for $\kappa K>2$. In the presence of the positive cosmological term, power-law regimes turn to the exponential (de Sitter) ones, while the recollapse regime turns to the exponential if the value for the $\mathrm{\Lambda }$-term is sufficiently large, otherwise the regime remains recollapse. The negative cosmological term leads to the recollapse regardless of $\kappa K$. All nonsingular regimes have the squashing coefficient $a(t)\to 1$ at late times, which is associated with restoring symmetry dynamics. Also all nonsingular regimes appear to be linearly stable exponential solutions always, while power-law regimes for an open region of the initial conditions.