We discuss methods for estimating $EB$ and $TB$ spectra of the cosmic microwave background anisotropy maps covering limited sky area. Such odd-parity correlations are expected to vanish whenever parity is not broken. As this is indeed the case in the standard cosmologies, any evidence to the contrary would have a profound impact on our theories of the early Universe. Such correlations could also become a sensitive diagnostic of some particularly insidious instrumental systematics. In this work we introduce three different unbiased estimators based on the so-called standard and pure pseudo-spectrum techniques and later assess their performance by means of extensive Monte Carlo simulations performed for different experimental configurations. We find that a hybrid approach combining a pure estimate of $B$-mode multipoles with a standard one for $E$-mode (or $T$) multipoles, leads to the smallest error bars for both $EB$ (or $TB$ respectively) spectra as well as for the three other polarization-related angular power spectra (i.e., $EE$, $BB$, and $TE$). However, if both $E$ and $B$ multipoles are estimated using the pure technique, the loss of precision for the $EB$ spectrum is not larger than $\sim 30\%$. Moreover, for the experimental configurations considered here, the statistical uncertainties-due to sampling variance and instrumental noise-of the pseudo-spectrum estimates is at most a factor $\sim 1.4$ for $TT$, $EE$, and $TE$ spectra and a factor $\sim 2$ for $BB$, $TB$, and $EB$ spectra, higher than the most optimistic Fisher estimate of the variance.

We consider the interesting “near-horizon test” reported in S. E. P. Bergliaffa and Y. E. C. de O. Nunes, Phys. Rev. D 84, 084006 (2011) for any static, spherically symmetric black hole solution admitted in $\mathrm{f}(\mathrm{R})$ gravity. Before adopting the necessary conditions for the test, however, revisions are needed as we point out in this Comment.

We consider multiflavor QED on a finite lattice at a finite chemical potential and show that the partition function only depends on the variables, ($\frac{{\mu }_i}{q_i}-\frac{{\mu }_1}{q_1}$), for $i=2,\cdots$, where $q_i$, $i=1\cdots$ are integer valued charges of the various flavors and ${\mu }_i$, $i=1\cdots$ are the dimensionless chemical potentials of the various flavors.

Numerical simulations of the supernova (SN) neutrino self-induced flavor conversions, associated with the neutrino-neutrino interactions in the deepest stellar regions, have been typically carried out assuming the “bulb model.” In this approximation, neutrinos are taken to be emitted half-isotropically by a common neutrinosphere. In the recent [A. Mirizzi and P. D. Serpico, Phys. Rev. Lett. 108, 231102 (2012)] we have removed this assumption by introducing flavor-dependent angular distributions for SN neutrinos, as suggested by core-collapse simulations. We have found that in this case a novel multiangle instability in the self-induced flavor transitions can arise. In this work we perform an extensive study of this effect, carrying out a linearized flavor stability analysis for different SN neutrino energy fluxes and angular distributions, in both normal and inverted neutrino mass hierarchy. We confirm that spectra of different $\nu$ species which cross in angular space (where $F_{{\nu }_e}=F_{{\nu }_x}$ and $F_{{\overline{\nu }}_e}=F_{{\overline{\nu }}_x}$) present a significant enhancement of the flavor instability, and a shift of the onset of the flavor conversions at smaller radii with respect to the case of an isotropic neutrino emission. We also illustrate how a qualitative (and sometimes quantitative) understanding of the dynamics of these systems follows from a stability analysis.

Near conformal dynamics is employed in different extensions of the standard model of particle interactions as well as in cosmology. Many of its interesting properties are either conjectured or determined using model computations. We introduce a relevant four-dimensional gauge theory template allowing us to investigate such dynamics perturbatively. The gauge theory we consider is quantum chromodynamics with the addition of a mesonlike scalar degree of freedom as well as an adjoint Weyl fermion. At the two-loop level, and in the Veneziano limit, we firmly establish the existence of several fixed points of which one is all directions stable in the infrared. An interesting feature of the model is that this fixed point is lost within the perturbative regime by merging with another fixed point when varying the number of quark flavors. We show the emergence of Miransky scaling and determine its properties. The theory exhibits walking behavior in the region close to the lower bound of the conformal window, and by providing a suitable definition we determine the walking region. Finally, we also determine the anomalous dimension of the fermion mass, which is a highly relevant quantity for near conformal dynamics.

We give a detailed analysis of the effects of scheme transformations in the vicinity of an exact or approximate infrared fixed point in an asymptotically free gauge theory with fermions. We list necessary conditions that such transformations must obey and show that, although these can easily be satisfied in the vicinity of an ultraviolet fixed point, they constitute significant restrictions on scheme transformations at an infrared fixed point. We construct acceptable scheme transformations and use these to study the scheme-dependence of an infrared fixed point, making comparison with our previous three-loop and four-loop calculations of the location of this point in the $\overline{MS}$ scheme. We also use an illustrative hypothetical exact $\beta$ function to investigate how accurately analyses of finite-order series expansions probe an infrared fixed point and the effect of a scheme transformation on these. Some implications of our work are discussed.

We investigate the evolution of the Universe filled with barotropic perfect fluid in Eddington-inspired Born-Infeld gravity. We consider both the isotropic and the anisotropic universe. At the early stage when the energy density is high, the evolution is modified considerably compared with that in general relativity. For the equation-of-state parameter $w>0$, the initial singularity is not accompanied as it was discovered for radiation in earlier work. More interestingly, for pressureless dust ($w=0$), the initial state approaches a de Sitter state. This fact opens a new possibility of the singularity-free nature of the theory. The anisotropy is mild, and does not develop curvature singularities in spacetime contrary to general relativity.

The detection of gravitational waves from binary neutron stars is a major goal of the gravitational-wave observatories Advanced LIGO and Advanced Virgo. Previous searches for binary neutron stars with LIGO and Virgo neglected the component stars’ angular momentum (spin). We demonstrate that neglecting spin in matched-filter searches causes advanced detectors to lose more than 3% of the possible signal-to-noise ratio for 59% (6%) of sources, assuming that neutron star dimensionless spins, $c\mathbf{J}/G{M}^2$, are uniformly distributed with magnitudes between 0 and 0.4 (0.05) and that the neutron stars have isotropically distributed spin orientations. We present a new method for constructing template banks for gravitational-wave searches for systems with spin. We present a new metric in a parameter space in which the template placement metric is globally flat. This new method can create template banks of signals with nonzero spins that are (anti-)aligned with the orbital angular momentum. We show that this search loses more than 3% of the maximum signal-to-noise for only 9% (0.2%) of binary neutron star sources with dimensionless spins between 0 and 0.4 (0.05) and isotropic spin orientations. Use of this template bank will prevent selection bias in gravitational-wave searches and allow a more accurate exploration of the distribution of spins in binary neutron stars.

We compute the linearized Weyl-Weyl correlator using a new solution for the graviton propagator on de Sitter background in de Donder gauge. The result agrees exactly with a previous computation in a noncovariant gauge. We also use dimensional regularization to compute the one-loop expectation value of the square of the Weyl tensor.

In this paper it is shown that Tolman’s law can be derived from relativistic kinetic theory applied to a simple fluid in a BGK-like approximation. Using this framework, it becomes clear that the contribution of the gravitational field can be viewed as a cross effect that resembles the so-called Thomson effect in irreversible thermodynamics. A proper generalization of Tolman’s law in an inhomogeneous medium is formally established based on these grounds.

The infrared structure of quantum gravity is explored by solving a lattice version of the Wheeler-DeWitt equations. In the present paper only the case of $2+1$ dimensions is considered. The nature of the wave function solutions is such that a finite correlation length emerges and naturally cuts off any infrared divergences. Properties of the lattice vacuum are consistent with the existence of an ultraviolet fixed point in $G$ located at the origin, thus precluding the existence of a weak coupling perturbative phase. The correlation length exponent is determined exactly and found to be $\nu =6/11$. The results obtained so far lend support to the claim that the Lorentzian and Euclidean formulations belong to the same field-theoretic universality class.

We discuss the set of constraints for Einstein-aether theories, comparing the flat background case with what is expected when the gravitational fields are dynamic. We note potential pathologies occurring in the weak gravitational field limit for some of the Einstein-aether theories.

We investigate the perihelion shift of planetary motion in conformal Weyl gravity using the metric of the static, spherically symmetric solution discovered by Mannheim and Kazanas [Astrophys. J. 342, 635 (1989)]. To this end we employ a procedure similar to that used by Weinberg for the Schwarzschild solution, which has also been used recently to study the solar system effects of the cosmological constant $\Lambda$. We show that besides the general relativistic terms obtained earlier from the Schwarzschild–de Sitter solution, the expression for the perihelion shift includes a negative contribution which arises from the linear term $\gamma r$ in the metric. Using data for perihelion shift observations, we obtain constraints on the value of the constant $\gamma$ similar to that obtained earlier using galactic rotational curves.

Here we consider two phenomena in the vicinity of a black hole deformed by the tidal gravitational force of surrounding matter and by a strong magnetic field: equatorial motion of charged particles and the decay of a test scalar field. We were able to analyze both phenomena with analytical and simple numerical tools, which was unexpected given the low symmetry of the system. We show that both the tidal gravitational force and the magnetic field strongly enhance the release of the binding energy for the matter spiralling into the black hole. In the presence of the magnetic field, the left- and right-handed rotations of charged particles are not equivalent and for sufficiently large $|q|B$ there are stable anti-Larmor orbits very close to the event horizon, although Larmor orbits are only stable at some distance from the black hole. The larger the tidal force, the closer the innermost stable orbit to the black hole for both types of rotation. It is also shown that the real oscillation frequencies of the characteristic quasinormal modes are considerably suppressed by the tidal force.

We consider the multiverse in the intrinsically quantum mechanical framework recently proposed in Refs. [3,4]. By requiring that the principles of quantum mechanics are universally valid and that physical predictions do not depend on the reference frame one chooses to describe the multiverse, we find that the multiverse state must be static—in particular, the multiverse does not have a beginning or end. We argue that, despite its naive appearance, this does not contradict observation, including the fact that we observe that time flows in a definite direction. Selecting the multiverse state ultimately boils down to finding normalizable solutions to certain zero-eigenvalue equations, analogous to the case of the hydrogen atom. Unambiguous physical predictions would then follow, according to the rules of quantum mechanics.

Angular tension is an Arnowitt-Deser-Misner charge that contributes a work term to the first law of black hole mechanics when the range of an angular coordinate is varied and leads to a new Smarr formula for stationary black holes. A phase diagram for singly spinning $D=5$ black holes shows that angular tension resolves the degeneracies between spherical black holes and (dipole) black rings and captures the physics of the black ring balance condition. Angular tension depends on the behavior of the metric at rotational axes and we speculate on its relation to rod/domain structure characterizations of higher-dimensional black holes and black hole uniqueness theorems.

Based on three years of Fermi Large Area Telescope (LAT) gamma-ray data of the Virgo cluster, evidence for an extended emission associated with dark matter pair annihilation in the $b\overline{b}$ channel has been reported by Han et al. [arXiv:1201.1003]. After an in-depth spatial and temporal analysis, we argue that the tentative evidence for a gamma-ray excess from the Virgo cluster is mainly due to the appearance of a population of previously unresolved gamma-ray point sources in the region of interest. These point sources are not part of the LAT second source catalog (2FGL), but are found to be above the standard detection significance threshold when three or more years of LAT data are included.

We investigate the resonant leptogenesis scenario in the minimally $U(1{)}_{B-L}$ extended standard model with minimal flavor violation. In our model, the $U(1{)}_{B-L}$ gauge symmetry is broken at the TeV scale and standard model singlet neutrinos gain Majorana masses of order TeV. In addition, we introduce a flavor symmetry on the singlet neutrinos at a scale higher than TeV. The flavor symmetry is explicitly broken by the neutrino Dirac Yukawa coupling, which induces splittings in the singlet neutrino Majorana masses at lower scales through renormalization group evolutions. We call this setup minimal flavor violation. The mass splittings are proportional to the tiny Dirac Yukawa coupling, and hence they automatically enhance the $CP$ asymmetry parameter necessary for the resonant leptogenesis mechanism. In this paper, we calculate the baryon number yield by solving the Boltzmann equations, including the effects of $U(1{)}_{B-L}$ gauge boson that also has TeV scale mass and causes washing-out of the singlet neutrinos in the course of thermal leptogenesis. The Dirac Yukawa coupling for neutrinos is fixed in terms of neutrino oscillation data and an arbitrary $3\times 3$ complex-valued orthogonal matrix. We show that the right amount of baryon number asymmetry can be achieved through thermal leptogenesis in the context of the minimal flavor violation with singlet neutrinos and $U(1{)}_{B-L}$ gauge boson at the TeV scale. These particles can be discovered at the LHC in the near future.

We show that by adding a vectorlike $5+\overline{5}$ pair of matter fields to the spectrum of the minimal renormalizable supersymmetric $SU(5)$ theory the wrong relations for fermion masses can be corrected, while being predictive and consistent with proton lifetime limits. Threshold correction from the vectorlike fields improves the unification of gauge couplings compared to the minimal model. It is found that for supersymmetric spectra lighter than 3 TeV, which would be testable at the LHC, at least some of the nucleon decay modes should have partial lifetimes shorter than about $2\times {10}^{34}$ years, which is within reach of ongoing and proposed experiments.

We pursue a scenario where the lighter top squark (stop) mass is accessible for the Large Hadron Collider in the near future, while gluinos and first two generation squarks are too heavy. At $\sqrt{s}=8\mathrm{TeV}$, we investigate the identification of stops which decay predominantly into a top quark and the stable lightest supersymmetric particle. We use a simple kinematical variable, $M3$, to reconstruct two top quarks which are pair-produced from the stops, in the fully hadronic channel. The dominant Standard Model background for this signal stems from $t\overline{t}$ plus jets, with one top quark decaying into $bl\nu$, where the lepton is undetected and the $\nu$ produces missing transverse momentum. The lepton identification efficiency is thus crucial in order to estimate the background correctly. We identify kinematical variables to reduce the Standard Model background. We find that it is possible to achieve signal and background cross section at similar levels for stop masses around 300–500 GeV for a ${\tilde{\chi }}_1^0$ mass of 100 GeV.