We study the influence of phantom fields on strong field gravitational lensing. Supposing that the gravitational field of the supermassive central object of the Galaxy is described by a phantom black hole metric, we estimate the numerical values of the coefficients and observations and find that the influence of the phantom fields is somewhat similar to that of the electric charge in a Reissner-Nordström black hole, i.e., the deflect angle and angular separation increase with the phantom constant $b$. However, other observations are contrary to the Reissner-Nordström case and show the effects of dark energy, such as (i) compressing the usual black hole and more powerfully attracting photons, (ii) making the relativistic Einstein ring larger than that of the usual black hole, and (iii) not weakening the usual relative magnitudes, which will facilitate observations.

We present an approximate calculation of the full Bayesian posterior probability distribution for the local non-Gaussianity parameter $f_{\mathrm{nl}}$ from observations of cosmic microwave background anisotropies within the framework of information field theory. The approximation that we introduce allows us to dispense with numerically expensive sampling techniques. We use a novel posterior validation method (DIP test) in cosmology to test the precision of our method. It transfers inaccuracies of the calculated posterior into deviations from a uniform distribution for a specially constructed test quantity. For this procedure we study toy cases that use one- and two-dimensional flat skies, as well as the full spherical sky. We find that we are able to calculate the posterior precisely under a flat-sky approximation, albeit not in the spherical case. We argue that this is most likely due to an insufficient precision of the used numerical implementation of the spherical harmonic transform, which might affect other non-Gaussianity estimators as well. Furthermore, we present how a nonlinear reconstruction of the primordial gravitational potential on the full spherical sky can be obtained in principle. Using the flat-sky approximation, we find deviations for the posterior of $f_{\mathrm{nl}}$ from a Gaussian shape that become more significant for larger values of the underlying true $f_{\mathrm{nl}}$. We also perform a comparison to the well-known estimator of Komatsu et al. [Astrophys. J. 634, 14 (2005)] and finally derive the posterior for the local non-Gaussianity parameter $g_{\mathrm{nl}}$ as an example of how to extend the introduced formalism to higher orders of non-Gaussianity.

We present an exactly solvable model for the suppression of quantum noise at large scales on expanding space. The suppression arises naturally in the de Broglie-Bohm pilot-wave formulation of quantum theory, according to which the Born probability rule has a dynamical origin. For a scalar field on a radiation-dominated background we construct the exact solution for the time-evolving wave functional and study properties of the associated field trajectories. It is shown that the time evolution of a field mode on expanding space is mathematically equivalent to that of a standard harmonic oscillator with a “retarded time” that depends on the wavelength of the mode. In the far super-Hubble regime the equivalent oscillator evolves over only one Hubble time, yielding a simple mechanism whereby relaxation to the Born rule can be suppressed on very large scales. We present numerical simulations illustrating how the expansion of space can cause a retardation of relaxation in the super-Hubble regime. Given these results it is natural to expect a suppression of quantum noise at super-Hubble wavelengths. Such suppression could have taken place in a preinflationary era, resulting in a large-scale power deficit in the cosmic microwave background.

We consider a supersymmetric hybrid inflation scenario in which the $U(1)$ $R$ symmetry is explicitly broken by Planck scale suppressed operators in the superpotential. We provide an example with minimal Kähler potential, with the $R$-symmetry breaking term relevant during inflation being $\alpha S^4$, where $S$ denotes the well-known gauge singlet inflaton superfield. The inflationary potential takes into account the radiative and supergravity corrections as well as the soft supersymmetry breaking terms. For successful inflation, with the scalar spectral index in the currently preferred range, $n_s\approx 0.97\pm 0.010$, $|\alpha |\lesssim {10}^{-7}$. The tensor-to-scalar ratio $r\lesssim {10}^{-4}$, while $|\mathrm{d}{n}_s/\mathrm{d}\ln k|\sim \mathcal{O}({10}^{-3})-\mathcal{O}({10}^{-4})$.

Old and new calculations of the Higgs mass quadratic divergence are compared.

We compute the graviton Kaluza-Klein spectrum on a gravity-dilaton background with a naked singularity for all possible boundary conditions at the singularity which are consistent with unitary evolution. We apply methods from nonrelativistic quantum mechanics with singular Schrödinger potentials. In general, the spectrum contains a tachyon, a sign of instability. Only for a particular boundary condition at the singularity is the spectrum free of tachyons. In this case, the lowest-lying graviton mode is massless. We argue that this result will also hold for other backgrounds with similar geometry near the curvature singularity. We complete our study with a brief discussion on radion perturbations and the Higgs mechanism on this singular background.

The theoretical description of fermions in the presence of Lorentz and $CPT$ violation is developed. We classify all Lorentz- and $CPT$-violating and invariant terms in the quadratic Lagrange density for a Dirac fermion, including operators of arbitrary mass dimension. The exact dispersion relation is obtained in closed and compact form, and projection operators for the spinors are derived. The Pauli Hamiltonians for particles and antiparticles are extracted, and observable combinations of operators are identified. We characterize and enumerate the coefficients for Lorentz violation for any operator mass dimension via a decomposition using spin-weighted spherical harmonics. The restriction of the general theory to various special cases is presented, including isotropic models, the nonrelativistic and ultrarelativistic limits, and the minimal Standard-Model Extension. Expressions are derived in several limits for the fermion dispersion relation, the associated fermion group velocity, and the fermion spin-precession frequency. We connect the analysis to some other formalisms and use the results to extract constraints from astrophysical observations on isotropic ultrarelativistic spherical coefficients for Lorentz violation.

Matrix elements of flavor-diagonal light quark pseudoscalar densities and axial anomaly operators between vacuum and $\eta$ and ${\eta }^{\prime }$ meson states have been determined. This has been done by evaluating current-current correlators of octet-octet and octet-singlet axial currents using QCD sum rules. The numerical values obtained for the matrix elements compare well with those obtained in the current literature.

Dark sector mass relations, such as those which permit near-threshold or near-resonance annihilation in the early universe, could arise due to IR-attractive ratios in renormalization group equations. Achieving a particular ratio requires specific dark matter gauge charges or interactions, leading to predictions about the dark matter properties. Furthermore, additional states with masses comparable to the dark matter mass may be necessary, potentially giving rise to novel phenomenology. We explore this idea in the context of dark matter charged under a new gauged $U(1{)}_X$ that kinetically mixes with the standard model hypercharge.

We study the deep inelastic scattering and photo-production modes of $t\overline{t}$ pairs at the proposed LHeC and its potential to probe the electromagnetic and weak dipole moments (MDM and EDM for $tt\gamma$) of the top quark. A framework of eight independent gauge-invariant dimension-six operators involving the top quark and the electroweak gauge bosons is used. Four of these operators modify the charged $tbW$ coupling which can be probed through the single (anti)top production mode, as reported in the literature. One generates $tt\gamma (Z)$ as well as $tbW$ couplings, while the other two do not generate $tbW$ but only $tt\gamma (Z)$. Our focus is on the MDM and EDM of the top quark for which the photo-production mode of $t\overline{t}$ can be an excellent probe. At the proposed electron energies of $E_e=60$ and 140 GeV the LHeC could set constraints stronger than the indirect limits from $b\to s\gamma$ and the potential limits of the LHC through $t\overline{t}\gamma$ production.

We study the thermalization process in classical Yang–Mills field theory starting from noisy glasmalike initial conditions by investigating the initial-value sensitivity of trajectories. Kunihiro et al. linked entropy generation to the Kolmogorov–Sinaï entropy, which gives the entropy production rate in classical chaotic systems, calculated numerically for classical Yang–Mills fields starting from purely random initial field configurations. In contrast, we study here glasmalike initial conditions. For small random fluctuations, we obtain qualitatively similar results, while no entropy increase is observed when such fluctuations are absent. We analyze the intermediate-time Lyapunov spectrum for several time windows and calculate the Kolmogorov–Sinaï entropy. We find a large number of positive Lyapunov exponents at the early stages of time evolution. Also, for later times, their number is a sizeable fraction of the total number of degrees of freedom. The spectrum of positive Lyapunov exponents at first changes rapidly but then stabilizes, indicating that the dynamics of the gauge fields approaches a steady state. Thus, we conclude that also for glasmalike initial conditions, a significant amount of entropy is produced by classical gluon field dynamics.

The phase structure of magnetized cold quark matter is analyzed in the framework of the two-flavor Nambu-Jona-Lasinio models paying special attention to its dependence on the model parameters as different values within the phenomenological allowed range are considered. We first discuss the simpler chiral limit case, and then the more realistic situation of finite current masses. We show that in spite of the difference in the nature of some transitions, both cases are alike and exhibit a rather rich phase structure for a significant range of acceptable parameters. A simplification of the phase structure is obtained as parameters leading to larger values of the dressed quark mass in the vacuum are considered. Finally, we consider the so-called “inverse catalysis effect” showing that in some phases it implies an actual decrease of the order parameter as the magnetic field increases.

The axion modification of electrodynamics can be considered as produced by an irreducible part of the constitutive pseudotensor. In this paper, we study the modification of wave propagation produced by the second irreducible part, called the skewon. We introduce the notions of the skewon optic tensor and skewon optic covector. With these devices we prove that in a pseudo-Riemannian manifold endowed with an arbitrary skewon at least one solution of the dispersion relation is spacelike. This means that the skewon generates superluminal wave motion and is thus ruled out on the basis of special-relativistic principles.

A supersymmetric version of the recently proposed reduced minimal 331 model is considered and its Higgs sector is investigated. We focus on the mass spectrum of the lightest scalars of the model. We show that the Higgs mass of 125 GeV requires substantial radiative corrections. However, stops may develop small mixing and must have a mass around TeV. Moreover, some soft supersymmetry breaking terms may lie at the electroweak scale, which alleviates some tension concerning the fine-tuning of the related parameters. The lightest doubly charged scalar may have a mass of around a few hundreds of GeV, which can be probed at the LHC, while the remaining scalars of the model have masses at the TeV scale.

We discuss the ultraviolet (UV) to infrared (IR) evolution of asymptotically free chiral gauge theories. Various types of IR behavior are considered, including confinement without spontaneous chiral symmetry breaking, and formation of bilinear fermion condensates that preserve or dynamically break the chiral gauge invariance. We compare different schemes for the study of this evolution and the resultant IR structure of the theories, including a conjectured inequality based on the counting of degrees of freedom. We note some new patterns of UV to IR evolution.

We study spherically symmetric soliton solutions in a model with a conformally coupled scalar field as well as in full conformal gravity. We observe that a new type of limiting behavior appears for particular choices of the self-coupling of the scalar field, i.e. the solitons interpolate smoothly between the anti–de Sitter vacuum and an uncharged configuration. Furthermore, within conformal gravity the qualitative approach of a limiting solution does not change when varying the charge of the scalar field—contrary to the Einstein-Hilbert case. However, it changes with the scalar self-coupling.

We examine the steady-state spherically symmetric accretion of relativistic fluids, with a polytropic equation of state, onto a higher-dimensional Schwarzschild black hole. The mass accretion rate, critical radius, and flow parameters are determined and compared with results obtained in standard four dimensions. The accretion rate, $\dot{M}$, is an explicit function of the black hole mass, $M$, as well as the gas boundary conditions and the dimensionality, $D$, of the spacetime. We also find the asymptotic compression ratios and temperature profiles below the accretion radius and at the event horizon. This analysis is a generalization of Michel’s solution to higher dimensions and of the Newtonian expressions of Giddings and Mangano, which consider the accretion of TeV black holes.

Gravitational waves emitted during the inspiral, plunge and merger of a black hole binary carry linear momentum. This results in an astrophysically important recoil to the final merged black hole, a “kick” that can eject it from the nucleus of a galaxy. In a previous paper we showed that the puzzling partial cancellation of an early kick by a late antikick, and the dependence of the cancellation on black hole spin, can be understood from the phenomenology of the linear momentum waveforms. Here we connect that phenomenology to its underlying cause, the spin dependence of the inspiral trajectories. This insight suggests that the details of the plunge can be understood more broadly with a focus on inspiral trajectories.

We introduce and study extensions of the varying alpha theory of Bekenstein-Sandvik-Barrow-Magueijo to allow for an arbitrary coupling function and self-interaction potential term in the theory. We study the full evolution equations without assuming that variations in alpha have a negligible effect on the expansion scale factor and the matter density evolution, as was assumed in earlier studies. The background Friedmann-Robertson-Walker cosmology of this model in the cases of zero and nonzero spatial curvature is studied in detail, using dynamical systems techniques, for a wide class of potentials and coupling functions. All the asymptotic behaviors are found, together with some new solutions. We study the cases where the electromagnetic parameter, zeta, is positive and negative, corresponding to magnetic and electrostatic energy domination in the nonrelativistic matter. In particular, we investigate the cases where the scalar field driving alpha variations has exponential and power-law self-interaction potentials and the behavior of theories where the coupling constant between matter and alpha variations is no longer a constant.

Models of inflation in a gravitational background with an anisotropic space-time scaling are studied. The background is a higher-dimensional Lifshitz throat with the anisotropy scaling $z\ne 1$. After the dimensional reduction, the four-dimensional general covariance is explicitly broken to a three-dimensional spatial diffeomorphism. As a result the cosmological perturbation theory in this setup with less symmetries have to be formulated. We present the consistent cosmological perturbation theory for this setup. We find that the effective four-dimensional gravitational wave perturbations propagate with a different speed than the higher dimensional gravitational excitations. Depending on the model parameters, for an observer inside the throat, the four-dimensional gravitational wave propagation can be superluminal. We also find that the Bardeen potential and the Newtonian potential are different. This can have interesting observational consequences for lensing and cosmic microwave background fluctuations. Furthermore, we show that at the linearized level the inflaton field excitations vanish.