Recent anomalies in cosmic rays could be due to dark matter annihilation in our galaxy. In order to get the required large cross section to explain the data while still obtaining the right relic density, we rely on a nonstandard thermal history between dark matter freeze out and big-bang nucleosynthesis. We show that through a reheating phase from the decay of a heavy moduli or even the gravitino, we can produce the right relic density of dark matter if its self-annihilation cross section is large enough. In addition to fitting the recent data, this scenario solves the cosmological moduli and gravitino problems. We illustrate this mechanism with a specific example in the context of $U(1{)}_{B-L}$ extended minimal supersymmetric standard model where supersymmetry is broken via mirage mediation. These string motivated models naturally contain heavy moduli decaying to the gravitino, whose subsequent decay to the LSP can reheat the Universe at a low temperature. The right-handed sneutrino and the $B-L$ gaugino can both be viable dark matter candidates with a large cross section. They are leptophilic because of $B-L$ charges. We also show that it is possible to distinguish the nonthermal from the thermal scenario (using Sommerfeld enhancement) in direct detection experiments for certain regions of parameter space.

We calculate the inclusive and diffractive photoproduction of heavy quarks in proton-proton collisions at Tevatron and CERN LHC energies, where the photon reaches energies larger than those ones accessible at DESY-HERA. The integrated cross section and the rapidity distributions for charm and bottom production are computed within the color dipole picture employing three phenomenological saturation models based on the color glass condensate formalism. Our results demonstrate that the experimental analyses of these reactions are feasible and that the cross sections are sensitive to the underlying parton dynamics.

We investigate the $J/\psi$ polarization in photoproduction at the Hadron Electron Ring Accelerator (HERA) up to the next-to-leading order of QCD. The results show that the transverse momentum $p_t$ and energy fraction $z$ distributions of $J/\psi$ production do not agree with the observed ones very well. The theoretical uncertainties for the $z$ distributions of the $J/\psi$ polarization parameters with respect to various choices of the renormalization and factorization scales are too large to give a definite predication. The uncertainties for the $p_t$ distributions of these parameters are small when $p_t>3\mathrm{GeV}$ and the obtained $p_t$ distributions cannot describe the experimental data even in this region.

We compute the ${\Omega }^{-}$ electromagnetic form factors and the decuplet baryon magnetic moments using a quark model application of the covariant spectator theory. Our predictions for the ${\Omega }^{-}$ electromagnetic form factors can be tested in the future by lattice QCD simulations at the physical strange quark mass.

A disturbing aspect of Hawking’s derivation of black hole radiance is the need to invoke extreme conditions for the quantum field that originates the emitted quanta. It is widely argued that the derivation requires the validity of the conventional relativistic field theory to arbitrarily high, trans-Planckian scales. We stress in this note that this is not necessarily the case if the question is presented in a covariant way. We point out that Hawking radiation is immediately robust against an invariant Planck-scale cutoff. This important feature of Hawking radiation is relevant for a quantum gravity theory that preserves, in some way, the Lorentz symmetry.

We discuss fermionic reductions of type IIA superstrings on ${\mathrm{AdS}}_4\times {\mathbb{C}\mathbb{P}}^3$ in relation to the conjectured ${\mathrm{AdS}}_4/{\mathrm{CFT}}_3$ duality. The superstring theory is described by means of a coset model construction, which is classically integrable. We discuss the global light-cone symmetries of the action and related $\kappa$-symmetry gauge choices, and also present the complete quartic action in covariant form with respect to these. Further, we study integrable (fermionic) reductions, in particular, a reduction yielding a quadratic action of two complex fermions on the string world-sheet. Interestingly, this model appears to be exactly the same as the corresponding integrable reduction found in the ${\mathrm{AdS}}_5\times {\mathrm{S}}^5$ case.

In this work, we compare two different objects: electric black holes and magnetic black holes in arbitrary dimension. The comparison is made in terms of the corresponding moduli space and their extremal geometries. We treat parallelly the magnetic and the electric cases. Specifically, we discuss the gravitational solution of these spherically symmetric objects in the presence of a positive cosmological constant. Then, we find the bounded region of the moduli space allowing the existence of black holes. After identifying it in both the electric and the magnetic case, we calculate the geometry that comes out between the horizons at the coalescence points. Although the electric and magnetic cases are both very different (only dual in four dimensions), gravity solutions seem to clear up most of the differences and lead to very similar geometries.

We calculate the muon flux from annihilation of the dark matter in the core of the Sun, in the core of the Earth and from cosmic diffuse neutrinos produced in dark matter annihilation in the halos. We consider model-independent direct neutrino production and secondary neutrino production from the decay of taus produced in the annihilation of dark matter. We illustrate how muon energy distribution from dark matter annihilation has a very different shape than muon flux from atmospheric neutrinos. We consider both the upward muon flux, when muons are created in the rock below the detector, and the contained flux when muons are created in the (ice) detector. We contrast our results to the ones previously obtained in the literature, illustrating the importance of properly treating muon propagation and energy loss. We comment on neutrino flavor dependence and their detection.

The discovery of cosmic acceleration has presented a unique challenge for cosmologists. As observational cosmology forges ahead, theorists have struggled to make sense of a standard model that requires extreme fine-tuning. This challenge is known as the cosmological constant problem. The theory of gravitational aether is an alternative to general relativity that does not suffer from this fine-tuning problem, as it decouples the quantum field theory vacuum from geometry, while remaining consistent with other tests of gravity. In this paper, we study static black hole solutions in this theory and show that it manifests a UV-IR coupling: Aether couples the space-time metric close to the black hole horizon, to metric at infinity. We then show that using the trans-Planckian ansatz (as a quantum gravity effect) close to the black hole horizon, leads to an accelerating cosmological solution, far from the horizon. Interestingly, this acceleration matches current observations for stellar-mass black holes. Based on our current understanding of the black hole accretion history in the Universe, we then make a prediction for how the effective dark energy density should evolve with redshift, which can be tested with future dark energy probes.

Calibration errors in the response function of a gravitational-wave detector degrade its ability to detect and then to measure the properties of any detected signals. This paper derives the needed levels of calibration accuracy for each of these data-analysis tasks. The levels derived here are optimal in the sense that lower accuracy would result in missed detections and/or a loss of measurement precision, while higher accuracy would be made irrelevant by the intrinsic noise level of the detector. Calibration errors affect the data-analysis process in much the same way as errors in theoretical waveform templates. The optimal level of calibration accuracy is expressed therefore as a joint limit on modeling and calibration errors: increased accuracy in one reduces the accuracy requirement in the other.

We study the effects of a fourth generation $t^{\prime }$ quark in various extensions of the standard model. In the Randall-Sundrum model, the decay $t^{\prime }\to tZ$ has a large branching ratio that could be detected at the Large Hadron Collider (LHC). We also look at the two-Higgs doublet models I, II and III, and note that, in the latter, the branching ratio of $t^{\prime }\to t\varphi$, where $\varphi$ is a Higgs scalar or pseudoscalar, is huge and we discuss detection at the LHC.

Using the most general form of the interpolating current of the heavy spin $1/2$, ${\Sigma }_b$ baryon and distribution amplitudes of the nucleon, the transition form factors of the semileptonic ${\Sigma }_b\to Nl\nu$ decay are calculated in the framework of light-cone QCD sum rules. It is obtained that the form factors satisfy the heavy quark effective theory relations. The obtained results for the related form factors are used to estimate the decay rate of this transition.

Theories of interacting gauge fields and fermions can possess a running gauge coupling with an infrared-attractive fixed point (IRFP). We present a minimal description of the physics of these systems and comment on some simple expectations for results from lattice simulations done within the basin of attraction of the IRFP in these theories.

The $CP$-restoring phase transition at $\theta =\pi$ and high temperature is investigated using two related models that aim to describe the low-energy phenomenology of QCD, the Nambu-Jona-Lasinio (NJL) model and the linear sigma model coupled to quarks. Despite many similarities between the models, different predictions for the order of the phase transition result. Using the Landau-Ginzburg formalism, the origin of this difference is traced back to a nonanalytic vacuum term at zero temperature that is present in the NJL model, but usually not included in the linear sigma model. Because of the absence of explicit $CP$ violation, this term always alters the qualitative aspects of the high temperature phase transition at $\theta =\pi$, just as for $\theta =0$ in the chiral limit.

The gauge-mediated model of supersymmetry breaking implies that stable nontopological solitons, $Q$-balls, could form in the early Universe and comprise the dark matter. It is shown that the inclusion of the effects from gravity-mediation set an upper limit on the size of $Q$-balls. When in a dense baryonic environment $Q$-balls grow until reaching this limiting size at which point they fragment into two equal-sized $Q$-balls. This $Q$-splitting process will rapidly destroy a neutron star that absorbs even one $Q$-ball. The new limits on $Q$-ball dark matter require an ultralight gravitino $m_{3/2}\lesssim \mathrm{keV}$, naturally avoiding the gravitino overclosure problem, and providing the minimal supersymmetric standard model with a dark matter candidate where gravitino dark matter is not viable.

We present a 1-parameter deformation of four-dimensional De Sitter space within Einstein-Maxwell–De Sitter gravity and show that it is causal-geodesically complete.

We demonstrate that Majorana neutrinos can form Cooper pairs due to long-range attractive forces and show BCS superfluidity in a class of mass varying neutrino dark energy models. We describe the condensates for Majorana neutrinos and estimate the value of the gap, critical temperature, and Pippard coherence length for a simple neutrino dark energy model. In the strong coupling regime bosonic degree of freedom can become important, and Bose-Einstein condensate may govern the dynamics for the mass varying neutrino models. Formation of the condensates can significantly alter the instability scenario in the mass varying neutrino models.

An explicit global and unique isometric embedding into hyperbolic 3-space, $H^3$, of an axi-symmetric 2-surface with Gaussian curvature bounded below is given. In particular, this allows the embedding into $H^3$ of surfaces of revolution having negative, but finite, Gaussian curvature at smooth fixed points of the $U(1)$ isometry. As an example, we exhibit the global embedding of the Kerr-Newman event horizon into $H^3$, for arbitrary values of the angular momentum. For this example, considering a quotient of $H^3$ by the Picard group, we show that the hyperbolic embedding fits in a fundamental domain of the group up to a slightly larger value of the angular momentum than the limit for which a global embedding into Euclidean 3-space is possible. An embedding of the double-Kerr event horizon is also presented, as an example of an embedding that cannot be made global.

The Sultana-Dyer solution of general relativity representing a black hole embedded in a special cosmological background is analyzed. We find an expanding (weak) spacetime singularity instead of the reported conformal Killing horizon, which is covered by an expanding black hole apparent horizon (internal to a cosmological apparent horizon) for most of the history of the Universe. This singularity was naked early on. The global structure of the solution is studied as well.

With a well-motivated extension of higher order holonomy corrections, the quantum theory of loop quantum cosmology (LQC) for the $k=0$ Friedmann-Robertson-Walker model (with a free massless scalar) is rigorously formulated. The analytical investigation reveals that, regardless of the order of holonomy corrections and for any arbitrary states, the matter density remains finite, bounded from above by an upper bound, which equals the critical density obtained at the level of heuristic effective dynamics. Particularly, with all orders of corrections included, the dynamical evolution is shown to follow the bouncing scenario in which two Wheeler-DeWitt solutions (expanding and contracting) are bridged together through the quantum bounce. These observations provide further evidence that the quantum bounce is essentially a consequence of the intrinsic discreteness of LQC and LQC is fundamentally different from the WDW theory. Meanwhile, the possibility is also explored so that the higher order holonomy corrections can be interpreted as a result of admitting generic $SU(2)$ representations for the Hamiltonian constraint operators.