We consider the causal structure of generalized uncharged McVittie spacetimes with increasing central mass $m(t)$ and positive Hubble factor $H(t)$. Under physically reasonable conditions, namely, a big bang singularity in the past, a positive cosmological constant, and an upper limit to the central mass, we prove that the patch of the spacetime described by the cosmological time and areal radius coordinates is always geodesically incomplete, which implies the presence of event horizons in the spacetime. We also show that, depending on the asymptotic behavior of the $m$ and $H$ functions, the generalized McVittie spacetime can have a single black hole, a black-hole/white-hole pair or, differently from classic fixed-mass McVittie, a single white hole. A simple criterion is given to distinguish the different causal structures.

The geodesic equation in the five-dimensional singly rotating black ring is nonintegrable, unlike the case of the Myers-Perry black hole. In the Newtonian limit of the black ring, its geodesic equation agrees with the equation of motion of a particle in the Newtonian potential due to a homogeneous ring gravitational source. In this paper, we show that the Newtonian equation of motion allows the separation of variables in the spheroidal coordinates, providing a nontrivial constant of motion quadratic in momenta. This shows that the Newtonian limit of a black ring recovers the symmetry of its geodesic system, and the geodesic chaos is caused by relativistic effects.

Recent work in the literature has shown that the one-loop long distance quantum corrections to the Newtonian potential imply tiny but observable effects in the restricted three-body problem of celestial mechanics; i.e., at the Lagrangian libration points of stable equilibrium, the planetoid is not exactly at an equal distance from the two bodies of large mass, but the Newtonian values of its coordinates are changed by a few millimeters in the Earth-Moon system. First, we assess such a theoretical calculation by exploiting the full theory of the quintic equation, i.e., its reduction to Bring-Jerrard form and the resulting expression of roots in terms of generalized hypergeometric functions. By performing the numerical analysis of the exact formulas for the roots, we confirm and slightly improve the theoretical evaluation of quantum corrected coordinates of Lagrangian libration points of stable equilibrium. Second, we prove in detail that for collinear Lagrangian points the quantum corrections are also of the same order of magnitude in the Earth-Moon system. Third, we discuss the prospects of measuring, with the help of laser ranging, the above departure from the equilateral triangle picture, which is a challenging task. On the other hand, a modern version of the planetoid is the solar sail, and much progress has been made, in recent years, on the displaced periodic orbits of solar sails at all libration points, both stable and unstable. Therefore, the present paper investigates, eventually, a restricted three-body problem involving Earth, the Moon, and a solar sail. By taking into account the one-loop quantum corrections to the Newtonian potential, displaced periodic orbits of the solar sail at libration points are again found to exist.

We compute the instantaneous contributions to the spherical harmonic modes of gravitational waveforms from compact binary systems in general orbits up to the third post-Newtonian (PN) order. We further extend these results for compact binaries in quasielliptical orbits using the 3PN quasi-Keplerian representation of the conserved dynamics of compact binaries in eccentric orbits. Using the multipolar post-Minkowskian formalism, starting from the different mass and current-type multipole moments, we compute the spin-weighted spherical harmonic decomposition of the instantaneous part of the gravitational waveform. These are terms which are functions of the retarded time and do not depend on the history of the binary evolution. Together with the hereditary part, which depends on the binary’s dynamical history, these waveforms form the basis for construction of accurate templates for the detection of gravitational wave signals from binaries moving in quasielliptical orbits.

This paper investigates the manner in which classical universes are obtained in the no-boundary quantum state. In this context, universes can be characterized as classical [in a Wentzel-Kramers-Brillouin (WKB) sense] when the wavefunction is highly oscillatory, i.e. when the ratio of the change in the amplitude of the wavefunction becomes small compared to the change in the phase. In the presence of a positive or negative exponential potential, the WKB condition is satisfied in proportion to a factor $e^{-(\epsilon -3)N/(\epsilon -1)}$, where $\epsilon$ is the (constant) slow-roll/fast-roll parameter and $N$ designates the number of e-folds. Thus classicality is reached exponentially fast in $N$, but only when $\epsilon <1$ (inflation) or $\epsilon >3$ (ekpyrosis). Furthermore, when the potential switches off and the ekpyrotic phase goes over into a phase of kinetic domination, the level of classicality obtained up to that point is preserved. Similar results are obtained in a cyclic potential, where a dark energy plateau is added. Finally, for a potential of the form $-{\varphi }^n$ (with $n=4,6,8$), where the classical solution becomes increasingly kinetic dominated, there is an initial burst of classicalization which then quickly levels off. These results demonstrate that inflation and ekpyrosis, which are the only dynamical mechanisms known for smoothing the universe, share the perhaps even more fundamental property of rendering space and time classical in the first place.

Using a Green’s function approach, we compare the trajectories of classical Hamiltonian point particles in an expanding space-time to the effectively inertial trajectories in the Zel’dovich approximation. It is shown that the effective gravitational potential accelerating the particles relative to the Zel’dovich trajectories vanishes exactly initially as a consequence of the continuity equation, and acts only during a short, early period. The Green’s function approach suggests an iterative scheme for improving the Zel’dovich trajectories, which can be analytically solved. We construct these trajectories explicitly and show how they interpolate between the Zel’dovich and the exact trajectories. The effective gravitational potential acting on the improved trajectories is substantially smaller at late times than the potential acting on the exact trajectories. The results may be useful for Lagrangian perturbation theory and for numerical simulations.

It has been shown that the primordial perturbations sourced by inflation are driven to classicality by unitary evolution alone. However, their coupling with the environment such as photons and subsequent decoherence renders the cosmological correlations quantum, losing primordial information in the process. We argue that the quantumness of the resulting cosmological correlations is given by quantum discord, which captures nonclassical behavior beyond quantum entanglement. By considering the environment as a quantum channel in which primordial information contained in the perturbations is transmitted to us, we can then ask how much of this information is inaccessible. We show that this amount of information is given by the discord of the joint primordial perturbations-environment system. To illustrate these points, we model the joint system as a mixed bimodal Gaussian state, and show that quantum discord is dependent on the basis which decoherence occurs.

The effects of non-Gaussianity on the constraints on the primordial curvature perturbation power spectrum from primordial black holes (PBHs) are considered. We extend previous analyses to include the effects of coupling between the modes of the horizon scale at the time the PBH forms and superhorizon modes. We consider terms of up to third order in the Gaussian perturbation. For the weakest constraints on the abundance of PBHs in the early universe (corresponding to a fractional energy density of PBHs of $10^{-5}$ at the time of formation), in the case of Gaussian perturbations, constraints on the power spectrum are ${\mathcal{P}}_{\zeta }<0.05$ but can be significantly tighter when even a small amount of non-Gaussianity is considered, to ${\mathcal{P}}_{\zeta }<0.01$, and become approximately ${\mathcal{P}}_{\zeta }<0.003$ in more special cases. Surprisingly, even when there is negative skew (which naively would suggest fewer areas of high density, leading to weaker constraints), we find that the constraints on the power spectrum become tighter than the purely Gaussian case—in strong contrast with previous results. We find that the constraints are highly sensitive to both the non-Gaussianity parameters as well as the amplitude of superhorizon perturbations.

In this work, we analyze two possible alternative and model-independent approaches to describe the inflationary period. The first one assumes a general equation of state during inflation due to Mukhanov, while the second one is based on the slow-roll hierarchy suggested by Hoffman and Turner. We find that, remarkably, the two approaches are equivalent from the observational viewpoint, as they single out the same areas in the parameter space, and agree with the inflationary attractors where successful inflation occurs. Rephrased in terms of the familiar picture of a slowly rolling, canonically normalized scalar field, the resulting inflaton excursions in these two approaches are almost identical. Furthermore, once the Galactic dust polarization data from Planck are included in the numerical fits, inflaton excursions can safely take sub-Planckian values.

The direct detection of gravitational waves with the next-generation detectors, like Advanced LIGO, provides the opportunity to measure deviations from the predictions of general relativity. One such departure would be the existence of alternative polarizations. To measure these, we study a single detector measurement of a continuous gravitational wave from a triaxial pulsar source. We develop methods to detect signals of any polarization content and distinguish between them in a model-independent way. We present LIGO Science Run 5 sensitivity estimates for 115 pulsars.

In most extensions of the Standard Model, heavy charged Higgs bosons at the LHC are dominantly produced in association with heavy quarks. An up-to-date determination of the next-to-leading-order total cross section in a type-II two-Higgs-doublet model is presented, including a thorough estimate of the theoretical uncertainties due to missing higher-order corrections, parton distribution functions and physical input parameters. Predictions in the four- and five-flavor schemes are compared and reconciled through a recently proposed scale-setting prescription. A four- and five-flavor scheme matched prediction is provided for the interpretation of current and future experimental searches for heavy charged Higgs bosons at the LHC.

The possibility for our visible world to be a 3-brane embedded in a multidimensional bulk is at the heart of many theoretical edifices in high-energy physics. Probing the braneworld hypothesis is thus a major experimental challenge. Following recent theoretical works showing that matter swapping between braneworlds can occur, we propose a neutron-shining-through-a-wall experiment. We first show that an intense neutron source such as a nuclear reactor core can induce a hidden neutron flux in an adjacent hidden braneworld. We then describe how a low-background detector can detect neutrons arising from the hidden world and quantify the expected sensitivity to the swapping probability. As a proof of concept, a constraint is derived from previous experiments.

We propose a new locally smeared operator product expansion to decompose nonlocal operators in terms of a basis of smeared operators. The smeared operator product expansion formally connects nonperturbative matrix elements determined numerically using lattice field theory to matrix elements of nonlocal operators in the continuum. These nonperturbative matrix elements do not suffer from power-divergent mixing on the lattice, which significantly complicates calculations of quantities such as the moments of parton distribution functions, provided the smearing scale is kept fixed in the continuum limit. The presence of this smearing scale complicates the connection to the Wilson coefficients of the standard operator product expansion and requires the construction of a suitable formalism. We demonstrate the feasibility of our approach with examples in real scalar field theory.

We present a study of the central exclusive ${\pi }^{+}{\pi }^{-}$ production via the photoproduction mechanism in nucleon-nucleon collisions. The photon-pomeron/reggeon and pomeron/reggeon-photon exchanges both for the $\rho (770)$ resonance, the Drell-Söding, and for the $\rho (1450)$ contributions are considered. The amplitudes for the processes are formulated in terms of vertices respecting the standard crossing and charge-conjugation relations of quantum field theory. The coupling parameters of tensor pomeron and reggeon exchanges are fixed based on the HERA experimental data for the $\gamma p\to {\rho }^{0}p$ reaction. We present first predictions of this mechanism for the $pp\to pp{\pi }^{+}{\pi }^{-}$ reaction being studied at COMPASS, RHIC, Tevatron, and LHC. We show the influence of the experimental cuts on the integrated cross section and on various differential distributions for outgoing particles. Distributions in rapidities and transverse momenta of outgoing protons and pions as well as correlations in the azimuthal angle between them are presented. We compare the photoproduction contribution to ${\pi }^{+}{\pi }^{-}$ distributions with double pomeron/reggeon two-pion continuum including the absorption effects. We discuss whether the high-energy central production of isovector $\rho$ resonances could be selected experimentally.

We discuss the renormalization of higher-derivative gravity, both without and with matter fields, in terms of two primary coupling constants rather than three. A technique for determining the dependence of the Gauss-Bonnet coupling constant on the remaining couplings is explained, and consistency with the local form of the Gauss-Bonnet relation in four dimensions is demonstrated to all orders in perturbation theory. A similar argument is outlined for the Hirzebruch signature and its coupling. We speculate upon the potential implications of instantons on the associated nonperturbative coupling constants.

As we showed in previous work, the dynamics and gravitational emission of binary neutron-star systems in certain scalar-tensor theories can differ significantly from that expected from general relativity (GR) in the coalescing stage. In this work we examine whether the characteristics of the electromagnetic counterparts to these binaries—driven by magnetosphere interactions prior to the merger event—can provide an independent way to test gravity in the most strongly dynamical stages of binary mergers. We find that the electromagnetic flux emitted by binaries in these scalar-tensor theories can show deviations from the GR prediction in particular cases. These differences are quite subtle, thus requiring delicate measurements to differentiate between GR and the type of scalar-tensor theories considered in this work using electromagnetic observations alone. However, if coupled with a gravitational-wave detection, electromagnetic measurements might provide a way to increase the confidence with which GR will be confirmed (or ruled out) by gravitational observations.

Assuming that axiomatic local field theory results hold for hadron scattering, André Martin and S. M. Roy recently obtained absolute bounds on the $D$ wave below threshold for pion-pion scattering and thereby determined the scale of the logarithm in the Froissart bound on total cross sections in terms of pion mass only. Previously, Martin proved a rigorous upper bound on the inelastic cross-section ${\sigma }_{\text{inel}}$ which is one-fourth of the corresponding upper bound on ${\sigma }_{\text{tot}}$, and Wu, Martin, Roy and Singh improved the bound by adding the constraint of a given ${\sigma }_{\text{tot}}$. Here we use unitarity and analyticity to determine, without any high-energy approximation, upper bounds on energy-averaged inelastic cross sections in terms of low-energy data in the crossed channel. These are Froissart-type bounds without any unknown coefficient or unknown scale factors and can be tested experimentally. Alternatively, their asymptotic forms, together with the Martin-Roy absolute bounds on pion-pion $D$ waves below threshold, yield absolute bounds on energy-averaged inelastic cross sections. For example, for ${\pi }^0{\pi }^0$ scattering, defining ${\sigma }_{\text{inel}}={\sigma }_{\text{tot}}-({\sigma }^{{\pi }^0{\pi }^0\to {\pi }^0{\pi }^0}+{\sigma }^{{\pi }^0{\pi }^0\to {\pi }^{+}{\pi }^{-}})$, we show that for c.m. energy $\sqrt{s}\to \infty$, ${\overline{\sigma }}_{\text{inel}}(s,\infty )\equiv s{\int }_s^{\infty }d{s}^{\prime }{\sigma }_{\text{inel}}(s^{\prime })/s^{\prime 2}\le (\pi /4)(m_{\pi }{)}^{-2}[\ln (s/s_1)+(1/2)\ln \ln (s/s_1)+1{]}^2$ where $1/s_1=34\pi \sqrt{2\pi }{m}_{\pi }^{-2}$. This bound is asymptotically one-fourth of the corresponding Martin-Roy bound on the total cross section, and the scale factor $s_1$ is one-fourth of the scale factor in the total cross section bound. The average over the interval (s,2s) of the inelastic ${\pi }^0{\pi }^0$ cross section has a bound of the same form with $1/s_1$ replaced by $1/s_2=2/s_1$.

We revisit an extension of the Standard Model with Majorana fermions in adjoint representations, where $SU(2{)}_L$ triplet and $SU(3{)}_c$ octet fermions are introduced. The model provides not only a precise coupling unification but also a dark matter candidate [an $SU(2{)}_L$ triplet fermion]. In particular, we show that an $SU(3{)}_c$ octet fermion, which is required for successful unification, can be a good nonthermal source of the triplet fermion dark matter. We also show that the scenario predicts a rather short lifetime of the proton compared with the minimal supersymmetric grand unified theory, and the most parameter space can be explored by future experiments such as the Hyper-Kamiokande experiment.

We analyze the thermodynamic behavior of the generalized scalar Yukawa model, composed of a complex scalar field interacting with scalar and vector fields. Finite-size effects on the phase structure are investigated using methods of quantum field theory on toroidal topologies. We focus on the analysis of the phase structure of this model at effective chemical equilibrium, under change of values of the relevant parameters of the model, looking especially to the influence of the spatial compactification on the phase structure.

In this paper we calculate the scale anomaly for a quantum field theoretic 2D-nonrelativistic Bose gas with contact interactions using Fujikawa’s method, both in vacuum and in many-body systems. The use of path integrals for these problems is novel and motivated by a recently developed path-integral framework for addressing questions about scaling in these systems. A natural class of regulators is found that produces the correct value of the anomaly traditionally calculated via other methods, e.g., diagrammatically via the $\beta$ function.