Light bosonic degrees of freedom have become a serious candidate for dark matter, which seems to pervade our entire Universe. The evolution of these fields around curved spacetimes is poorly understood but is expected to display interesting effects. In particular, the interaction of light bosonic fields with supermassive black holes, key players in most galaxies, could provide colorful examples of superradiance and nonlinear bosenovalike collapse. In turn, the observation of spinning black holes is expected to impose stringent bounds on the mass of putative massive bosonic fields in our Universe. Our purpose here is to present a comprehensive study of the evolution of linearized massive scalar and vector fields in the vicinities of rotating black holes. The evolution of generic initial data has a very rich structure, depending on the mass of the field and of the black hole. Quasinormal ringdown or exponential decay followed by a power-law tail at very late times is a generic feature of massless fields at intermediate times. Massive fields generically show a transition to power-law tails early on. For a certain boson field mass range, the field can become trapped in a potential barrier outside the horizon and transition to a bound state. Because there are a number of such quasibound states, the generic outcome is an amplitude modulated sinusoidal, or beating, signal, whose envelope is well described by the two lowest overtones. We believe that the appearance of such beatings has gone unnoticed in the past, and in fact mistaken for exponential growth. The amplitude modulation of the signal depends strongly on the relative excitation of the overtones, which in turn is strongly tied to the bound state geography. A fine-tuning of the initial data allows one to see the evolution of the nearly pure bound state mode that turns unstable for sufficiently large black hole (BH) rotation. For the first time we explore massive vector fields in a generic black hole background that are difficult, if not impossible, to separate in the Kerr background. Our results show that spinning BHs are generically strongly unstable against massive vector fields.

Inflation is the leading paradigm for explaining the origin of primordial density perturbations. However many open questions remain, in particular whether one or more scalar fields were present during inflation and how they contributed to the primordial density perturbation. We propose a new observational test of whether multiple fields or only one (not necessarily the inflaton) generated the perturbations. We show that our test, relating the bispectrum and trispectrum, is protected against loop corrections at all orders, unlike previous relations.

We use a global pixel-based estimator to identify the axis of the residual Maximum Temperature Asymmetry (MTA) (after the dipole subtraction) of the WMAP seven-year Internal Linear Combination (ILC) cosmic microwave background temperature sky map. The estimator is based on considering the temperature differences between opposite pixels in the sky at various angular resolutions (4°–15°) and selecting the axis that maximizes this difference. We consider three large-scale HEALPix resolutions: $N_{\mathrm{side}}=16(3.7°)$, $N_{\mathrm{side}}=8(7.3°)$ and $N_{\mathrm{side}}=4(14.7°)$. We compare the direction and magnitude of this asymmetry with three other cosmic asymmetry axes ($\alpha$ dipole, dark energy dipole and dark flow) and find that the four asymmetry axes are abnormally close to each other. We compare the observed MTA axis with the corresponding MTA axes of ${10}^4$ Gaussian isotropic simulated ILC maps (based on $\Lambda \mathrm{CDM}$). The fraction of simulated ILC maps that reproduce the observed magnitude of the MTA asymmetry and alignment with the observed $\alpha$ dipole is in the range of 0.1%–0.5% (depending on the resolution chosen for the cosmic microwave background map). The corresponding $\mathrm{\text{magnitude}}+\mathrm{\text{alignment}}$ probabilities with the other two asymmetry axes (dark energy dipole and dark flow) are at the level of about 1%. We propose Extended Topological Quintessence as a physical model qualitatively consistent with this coincidence of directions.

We study a class of dark matter models in which the dark matter is a baryon-like composite particle of a confining gauge group and also a pseudo-Nambu-Goldstone boson associated with the breaking of an enhanced chiral symmetry group. The approximate symmetry decouples the dark matter mass from the confinement scale of the new gauge group, leading to correct thermal relic abundances for dark matter masses far below the unitary bound, avoiding the typical conclusion of thermally produced composite dark matter. We explore the available parameter space in a minimal example model based on an SU(2) gauge group, and discuss prospects for experimental detection.

One of the most pernicious theoretical systematics facing upcoming gravitational lensing surveys is the uncertainty introduced by the effects of baryons on the power spectrum of the convergence field. One method that has been proposed to account for these effects is to allow several additional parameters (that characterize dark matter halos) to vary and to fit lensing data to these halo parameters concurrently with the standard set of cosmological parameters. We test this method. In particular, we use this technique to model convergence power spectrum predictions from a set of cosmological simulations. We estimate biases in dark energy equation-of-state parameters that would be incurred if one were to fit the spectra predicted by the simulations either with no model for baryons or with the proposed method. We show that neglecting baryonic effect leads to biases in dark energy parameters that are several times the statistical errors for a survey like the Dark Energy Survey. The proposed method to correct for baryonic effects renders the residual biases in dark energy equation-of-state parameters smaller than the statistical errors. These results suggest that this mitigation method may be applied to analyze convergence spectra from a survey like the Dark Energy Survey. For significantly larger surveys, such as will be carried out by the Large Synoptic Survey Telescope, the biases introduced by baryonic effects are much more significant. We show that this mitigation technique significantly reduces the biases for such larger surveys, but that a more effective mitigation strategy will need to be developed in order ensure that the residual biases in these surveys fall below the statistical errors.

Cosmological perturbations are generally described by quantum fields on (curved but) classical space-times. While this strategy has a large domain of validity, it can not be justified in the quantum gravity era where curvature and matter densities are of Planck scale. Using techniques from loop quantum gravity, the standard theory of cosmological perturbations is extended to overcome this limitation. The new framework sharpens conceptual issues by distinguishing between the true and apparent trans-Planckian difficulties and provides sufficient conditions under which the true difficulties can be overcome within a quantum gravity theory. In a companion paper, this framework is applied to the standard inflationary model, with interesting implications to theory as well as observations.

We perform a detailed comparison between the Finsler-Randers cosmological model and the Dvali, Gabadadze, and Porrati (DGP) braneworld model. If we assume that the spatial curvature is strictly equal to zero then we prove the following interesting proposition: despite the fact that the current cosmological models have a completely different geometrical origin, they share exactly the same Hubble expansion. This implies that the Finsler-Randers model is cosmologically equivalent with that of the DGP model as far as the cosmic expansion is concerned. At the perturbative level we find that the Finsler-Randers growth index of matter perturbations is ${\gamma }_{\mathrm{FR}}\simeq 9/14$, which is somewhat lower than that of DGP gravity (${\gamma }_{\mathrm{DGP}}\simeq 11/16$), implying that the growth factor of the Finsler-Randers model is slightly different ($\sim 0.1–2\%$) from the one provided by the DGP gravity model.

Total-angular-momentum (TAM) waves provide a set of basis functions for scalar, vector, and tensor fields that can be used in place of plane waves and that reflect the rotational symmetry of the spherical sky. Here we discuss three-point correlation functions, or bispectra in harmonic space, for scalar, vector, and tensor fields in terms of TAM waves. The Wigner-Eckart theorem dictates that the expectation value, assuming statistical isotropy, of the product of three TAM waves is the product of a Clebsch-Gordan coefficient (or Wigner-3j symbol) times a function only of the total-angular-momentum quantum numbers. Here we show how this works, and we provide explicit expressions relating the bispectra for TAM waves in terms of the more commonly used Fourier-space bispectra. This formalism will be useful to simplify calculations of projections of three-dimensional bispectra onto the spherical sky.

Lepton mixing, which requires physics beyond the Standard Model, is surprisingly compatible with a minimal, symmetryless and unbiased approach, called anarchy. This contrasts with highly involved flavor symmetry models. On the other hand, hints for light sterile neutrinos have emerged from a variety of independent experiments and observations. If confirmed, their existence would represent a groundbreaking discovery, calling for a theoretical interpretation. We discuss anarchy in the two-neutrino eV-scale seesaw framework. The distributions of mixing angles and masses according to anarchy are in agreement with global fits for the active and sterile neutrino parameters. Our minimal and economical scenario predicts the absence of neutrinoless double beta decay and one vanishing neutrino mass, and can therefore be tested in future experiments.

We study the possible LHC collider signatures in the next-to-minimal supersymmetric standard model. The general next-to-minimal supersymmetric standard model consists of 29 supersymmetric particles which can be mass ordered in $29!\simeq 9\times {10}^{30}$ ways. To reduce the number of hierarchies to a more manageable amount we assume a degeneracy of the sfermions of the first two generations with the same quantum numbers. Further assumptions about the neutralino and chargino masses leave 15 unrelated parameters. We check all $15!\approx {10}^{12}$ relevant mass orderings for the dominant decay chains and the corresponding collider signatures at the LHC. As preferred signatures, we consider charged leptons, missing transverse momentum, jets, and $W$, $Z$ or Higgs bosons. We present the results for three different choices of the singlet to Higgs coupling $\lambda$: (a) small, $O(\lambda )<O(Y_{\tau })$, (b) large, $O(\lambda )\simeq O(Y_{\mathrm{top}},Y_b,Y_{\tau })$, and (c) dominant, $O(\lambda )>O(Y_{\mathrm{top}})$. We compare these three scenarios with the MSSM expectations as well as among each other. We also mention a possible mass hierarchy leading to seven jets plus one lepton signatures at the LHC and comment briefly on the consequence of possible $R$-parity violation.

The current Large Hadron Collider data indicate that the newly observed resonance has the $WW$ and $ZZ$ modes consistent with the standard model Higgs boson, while the $\gamma \gamma$ mode is about 1.2–2 times that of the standard model prediction and the tau-pair mode is suppressed. If this pattern persists in the upcoming data, it would be a sign for physics beyond the standard model. In the type II two-Higgs-doublet model, it is the region where $\sin \alpha \approx 0$ and a moderately large $\tan \beta =10–20$ that the lighter $CP$-even Higgs boson can accommodate the current data. We note that in this region the heavier $CP$-even Higgs boson must have a large decay branching ratio into tau pairs. We find that this heavier Higgs boson can be observable in the associated production with a $b\overline{b}$ pair and through the decay into a tau pair.

The possibility to measure jet-gap-jet final states in double-Pomeron-exchange events at the LHC is presented. In the context of the ATLAS experiment with additional forward physics detectors, cross sections for different experimental settings and gap definitions are estimated. This is done in the framework of the forward physics Monte Carlo interfaced with a perturbative QCD model that successfully reproduces standard jet-gap-jet cross sections at the Tevatron. The extrapolation to LHC energies follows from the Balitsky-Fadin-Kuraev-Lipatov dynamics, implemented in the model at next-to-leading logarithmic accuracy.

Double parton scattering is sensitive to correlations between the two partons in the hadron, including correlations in flavor, spin, color, momentum fractions and transverse separation. We obtain a first estimate of the size of these correlations by calculating the corresponding double parton distribution functions in a bag model of the proton. We find significant correlations between momentum fractions, spin and flavor, but negligible correlations with transverse separation. The model estimates of the relative importance of these correlations will help experimental studies disentangle them.

We present a detailed, all-order study of gluon mass generation within the massless bound-state formalism, which constitutes the general framework for the systematic implementation of the Schwinger mechanism in non-Abelian gauge theories. The main ingredient of this formalism is the dynamical formation of bound states with vanishing mass, which give rise to effective vertices containing massless poles; these latter vertices, in turn, trigger the Schwinger mechanism, and allow for the gauge-invariant generation of an effective gluon mass. This particular approach has the conceptual advantage of relating the gluon mass directly to quantities that are intrinsic to the bound-state formation itself, such as the “transition amplitude” and the corresponding “bound-state wave function.” As a result, the dynamical evolution of the gluon mass is largely determined by a Bethe-Salpeter equation that controls the dynamics of the relevant wave function, rather than the Schwinger-Dyson equation of the gluon propagator, as happens in the standard treatment. The precise structure and field-theoretic properties of the transition amplitude are scrutinized in a variety of independent ways. In particular, a parallel study within the linear-covariant (Landau) gauge and the background-field method reveals that a powerful identity, known to be valid at the level of conventional Green’s functions, also relates the background and quantum transition amplitudes. Despite the differences in the ingredients and terminology employed, the massless bound-state formalism is absolutely equivalent to the standard approach based on Schwinger-Dyson equations. In fact, a set of powerful relations allows one to demonstrate the exact coincidence of the integral equations governing the momentum evolution of the gluon mass in both frameworks.

We investigate the weak decays of $B_c$ mesons in Cabibbo-Kobayashi-Maskawa-favored and -suppressed modes. We present a detailed analysis of the $B_c$ meson decaying to a vector meson ($V$) and an axial-vector meson ($A$) in the final state. We also give the form factors involving the $B_c\to A$ transition in the Isgur-Scora-Grinstein-Wise II framework and, consequently, predict the branching ratios of $B_c\to VA$ and $AA$ decays.

Recently, ATLAS and CMS measured both overall and differential $W^{+}{W}^{-}$ cross sections that differ from next to leading order standard model predictions. While these measurements are not yet statistically significant enough to rule out the standard model, we demonstrate that the data from both experiments can be better fit with the inclusion of electroweak gauginos with masses of $\mathcal{O}(100)\mathrm{GeV}$. We show that these gauginos are consistent with other searches or measurements and can have ramifications for Higgs phenomenology.

In this work, we propose a $CPT$-even and Lorentz-violating dimension-five nonminimal coupling between fermionic and gauge fields, involving the $CPT$-even and Lorentz-violating gauge tensor of the Standard Model extension. This nonminimal coupling modifies the Dirac equation, whose nonrelativistic regime is governed by a Hamiltonian which induces new effects, such as an electric-Zeeman-like spectrum splitting and an anomalouslike contribution to the electron magnetic moment, among others. Some of these new effects allow one to constrain the magnitude of this nonminimal coupling in 1 part in ${10}^{16}(\mathrm{eV}{)}^{-1}$.

We evaluate in great detail one-loop four-graviton field theory amplitudes in pure $\mathcal{N}=4$ $D=4$ supergravity. The expressions are obtained by taking the field theory limits of (4,0) and (2,2) space-time supersymmetric string theory models. For each model we extract the contributions of the spin-1 and spin-2 $\mathcal{N}=4$ supermultiplets running in the loop. We show that all of those constructions lead to the same four-dimensional result for the four-graviton amplitudes in pure supergravity even though they come from different string theory models.

We derive the equations of motion of an electrically neutral test particle for modified gravity theories for which the covariant divergence of the ordinary matter energy-momentum tensor does not vanish (i.e., ${\nabla }_{\mu }{T}^{\mu \nu }\ne 0$). In fact, we generalize the Mathisson-Papapetrou equations by deriving a general form for the equations of motion of a test particle. Furthermore, using the generalized Mathisson-Papapetrou equations, we investigate the equations of motion of a pole-dipole (spinning) particle in the context of modified gravity.

Light scalar fields called moduli arise from a variety of different models involving supersymmetry and/or string theory; thus their existence is a generic prediction of leading theories for physics beyond the standard model. They also present a formidable, long-standing problem for cosmology. We argue that an anthropic solution to the moduli problem exists in the case of small moduli masses and that it automatically leads to dark matter in the form of moduli. The recent discovery of the 125 GeV Higgs boson implies a lower bound on the moduli mass of about a keV. This form of dark matter is consistent with the observed properties of structure formation, and it is amenable to detection with the help of x-ray telescopes. We present the results of a search for such dark matter particles using spectra extracted from the first deep x-ray observations of the Draco and Ursa Minor dwarf spheroidal galaxies, which are dark-matter-dominated systems with extreme mass-to-light ratios and low intrinsic backgrounds. No emission line is positively detected, and we set new constraints on the relevant new physics.