We carry out a complete and systematic study of all the possible one-zero textures for the neutrino mass matrix in light of the recent neutrino oscillation data which hint to a relatively large nonvanishing value for the smallest mixing angle (${\theta }_z$). We find that all the six possible one-zero textures are able to accommodate the experimental data, with five cases allowing also for noninvertible mass matrices. We present symmetry realizations for all the one-zero singular and nonsingular patterns in type-I and type-II seesaw mechanism schemes.

We prove in this paper that the electroweak $SU(4{)}_L\otimes U(1{)}_X$ gauge models with spontaneous symmetry breaking can offer a natural framework for generating neutrino masses by simply exploiting the tree level realization of dimension-five effective operators. The novelty of our approach resides in the fact that the scalar sector needs not to be enlarged, since these operators are constructed as direct products among scalar multiplets already existing in the model. There is a unique generic matrix for Yukawa couplings in the neutrino sector. The charged leptons are already in their diagonal basis. This framework can lead to a suitable fit of the established phenomenology for the left-handed neutrinos, while the right-handed neutrino masses come out in the sub-keV region, independently of the cutoff $\Lambda$. The latter introduces in the theory an intermediate scale (however, more close to GUT than to SM) at about ${10}^{12}\mathrm{GeV}$ which is a crucial ingredient for the left-handed neutrino phenomenology.

We perform amplitude analyses of the decays $B^0\to K^{+}{K}^{-}{K}_S^0$, $B^{+}\to K^{+}{K}^{-}{K}^{+}$, and $B^{+}\to K_S^0{K}_S^0{K}^{+}$, and measure $CP$-violating parameters and partial branching fractions. The results are based on a data sample of approximately $470\times {10}^6$ $B\overline{B}$ decays, collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at the SLAC National Accelerator Laboratory. For $B^{+}\to K^{+}{K}^{-}{K}^{+}$, we find a direct $CP$ asymmetry in $B^{+}\to \varphi (1020)K^{+}$ of $A_{CP}=(12.8\pm 4.4\pm 1.3)\%$, which differs from zero by $2.8\sigma$. For $B^0\to K^{+}{K}^{-}{K}_S^0$, we measure the $CP$-violating phase ${\beta }_{\mathrm{eff}}(\varphi (1020)K_S^0)=(21\pm 6\pm 2)°$. For $B^{+}\to K_S^0{K}_S^0{K}^{+}$, we measure an overall direct $CP$ asymmetry of $A_{CP}=(4_{-5}^{+4}\pm 2)\%$. We also perform an angular-moment analysis of the three channels and determine that the $f_X(1500)$ state can be described well by the sum of the resonances $f_0(1500)$, $f_2^{\prime }(1525)$, and $f_0(1710)$.

We study the one-loop effective potential for some Horava-Lifshitz-like theories.

We consider correlation functions of the stress-tensor or a conserved current in ${\mathrm{AdS}}_{d+1}/{\mathrm{CFT}}_d$ computed using the Hilbert or the Yang-Mills action in the bulk. We introduce new recursion relations to compute these correlators at tree-level. These relations have an advantage over the Britto-Cachazo-Feng-Witten (BCFW)-like relations described in arXiv:1102.4724 and arXiv:1011.0780 because they can be used in all dimensions including $d=3$. We also introduce a new method of extracting flat-space $S$-matrix elements from AdS/CFT correlators in momentum space. We show that the ($d+1$)-dimensional flat-space amplitude of gravitons or gluons can be obtained as the coefficient of a particular singularity of the $d$-dimensional correlator of the stress-tensor or a conserved current; this technique is valid even at loop-level in the bulk. Finally, we show that our recursion relations automatically generate correlators that are consistent with this observation: they have the expected singularity and the flat-space gluon, or graviton amplitude appears as its coefficient.

We adopt a superspace/supergraph formalism to pursue the investigation of the structure of one- and two-loop divergences in the frame of the minimal O’Raifeartaigh model that realizes the $F$-term spontaneous supersymmetry breaking. The linear delta expansion (LDE) procedure is introduced and renormalization is carried out up to the second order in the LDE expansion parameter. In agreement with the nonrenormalization theorem for the (chiral/antichiral) matter potential of $\mathcal{N}=1$, $D=4$ supersymmetry, our explicit supergraph calculations confirm that only the Kähler potential is actually renormalized.

We examine generalized O’Raifeartaigh models that feature multiple tree-level flat directions and only contain fields with $R$-charges 0 or 2. We show that spontaneous $R$-breaking at up to one-loop order is impossible in such theories. Specifically, we prove that the $R$-symmetric origin of field space is always a local minimum of the one-loop Coleman-Weinberg potential, generalizing an earlier result for the case of a single flat direction. This result has consequences for phenomenology and helps elucidate the behavior of various models of dynamical supersymmetry breaking.

The temperature dependence of the thermodynamic potential of quantum chromodynamics (QCD), the specific heat, and the quark effective mass are calculated for imbalanced quark matter in the limit of a large number of quark flavors (large-$N_F$), which corresponds to the random-phase approximation. Also a generalization of the relativistic Landau effective-mass relation in the imbalanced case is given, which is then applied to this thermodynamic potential.

We present a new iterative method to reduce eccentricity in black-hole-binary simulations. Given a good first estimate of low-eccentricity starting momenta, we evolve puncture initial data for $\sim 4$ orbits and construct improved initial parameters by comparing the inspiral with post-Newtonian calculations. Our method is the first to be applied directly to the gravitational-wave (GW) signal, rather than the orbital motion. The GW signal is in general less contaminated by gauge effects, which, in moving-puncture simulations, limit orbital-motion-based measurements of the eccentricity to an uncertainty of $\Delta e\sim 0.002$, making it difficult to reduce the eccentricity below this value. Our new method can reach eccentricities below ${10}^{-3}$ in one or two iteration steps; we find that this is well below the requirements for GW astronomy in the advanced detector era. Our method can be readily adapted to any compact-binary simulation with GW emission, including black-hole-binary simulations which use alternative approaches and neutron-star-binary simulations. We also comment on the differences in eccentricity estimates based on the strain $h$ and the Newman-Penrose scalar ${\Psi }_4$.

We study the four-dimensional Einstein-Yang-Mills black hole in the presence of a Dirac fermion field. Assuming a spherically symmetric, static, asymptotically flat black hole spacetime, we consider both massless and massive fermion fields. The $(4+1)$-dimensional Einstein-Yang-Mills system effectively reducing to the Einstein-Yang-Mills-Higgs-dilaton model was also taken into account. One finds that the fermion vacuum leads to the destruction of the black holes in question.

Recent numerical relativity simulations have shown that the final black hole produced in a binary merger can recoil with a velocity as large as $5000\mathrm{km}/\mathrm{s}$. Because of enhanced gravitational-wave emission in the so-called “hang-up” configurations, this maximum recoil occurs when the black-hole spins are partially aligned with the orbital angular momentum. We revisit our previous statistical analysis of post-Newtonian evolutions of black-hole binaries in the light of these new findings. We demonstrate that despite these new configurations with enhanced recoil velocities, spin alignment during the post-Newtonian stage of the inspiral will still significantly suppress (or enhance) kick magnitudes when the initial spin of the more massive black hole is more (or less) closely aligned with the orbital angular momentum than that of the smaller hole. We present a preliminary study of how this post-Newtonian spin alignment affects the ejection probabilities of supermassive black holes from their host galaxies with astrophysically motivated mass ratio and initial spin distributions. We find that spin alignment suppresses (enhances) ejection probabilities by $\sim 40\%$ (20%) for an observationally motivated mass-dependent galactic escape velocity, and by an even greater amount for a constant escape velocity of $1000\mathrm{km}/\mathrm{s}$. Kick suppression is thus at least a factor two more efficient than enhancement.

We use a de Sitter breaking graviton propagator [14,15] to compute the tree-order correlator between noncoincident Weyl tensors on a locally de Sitter background. An explicit and very simple result is obtained for any spacetime dimension $D$, in terms of a de Sitter invariant length function and the tensor basis constructed from the metric and derivatives of this length function. Our answer does not agree with the one derived previously by Kouris [26], but that result must be incorrect because it is not transverse and lacks some of the algebraic symmetries of the Weyl tensor. Taking the coincidence limit of our result (with dimensional regularization) and contracting the indices gives the expectation value of the square of the Weyl tensor at lowest order. We propose the next order computation of this as a true test of de Sitter invariance in quantum gravity.

A certain vector-tensor theory is revisited. It was proposed and analyzed as a theory of electromagnetism without the standard gauge invariance. Our attention is first focused on a detailed variational formulation of the theory, which leads to both a modified Lorentz force and the true energy-momentum tensor of the vector field. The theory is then applied to cosmology. A complete gauge invariant treatment of the scalar perturbations is presented. For appropriate gauge invariant variables describing the scalar modes of the vector field (A modes), it is proved that the evolution equations of these modes do not involve the scalar modes appearing in general relativity (GR modes), which are associated to the metric and the energy-momentum tensor of the cosmological fluids. However, the A modes modify the standard gauge invariant equations describing the GR modes. By using the new formalism, the evolution equations of the A perturbations are derived and separately solved and, then, the correction terms—due to the A perturbations—appearing in the evolution equations of the GR modes are estimated. The evolution of these correction terms is studied for an appropriate scale. The relevance of these terms depends on both the spectra and the values of the normalization constants involved in extended electromagnetism. Further applications of the new formalism will be presented elsewhere.

We will present a complete set of equations, in the form of an Einstein-Bianchi system, that describe the evolution of generic smooth lattices in spacetime. All 20 independent Riemann curvatures will be evolved in parallel with the leg lengths of the lattice. We will show that the evolution equations for the curvatures forms a hyperbolic system and that the associated constraints are preserved. This work is a generalization of our previous paper [L. Brewin, Phys. Rev. D 85, 124045 (2012)] on the Einstein-Bianchi system for the Schwarzschild spacetime to general $3+1$ vacuum spacetimes.

The second Bianchi identity can be recast as an evolution equation for the Riemann curvatures. Here we will report on such a system for a vacuum static spherically symmetric spacetime. This is the first of two papers. In the following paper we will extend the ideas developed here to general vacuum spacetimes. In this paper we will demonstrate our ideas on a Schwarzschild spacetime and give detailed numerical results. For suitable choices of lapse function we find that the system gives excellent results with long term stability.

In a previous paper [Phys. Rev. D 81, 043534 (2010)], we proposed a model where natural inflation is realized on a steep potential [$V(\varphi )\sim \cos (\varphi /f)$ with $f\ll M_P$] as a consequence of the interaction of the inflaton with gauge fields through the coupling $\varphi F_{\mu \nu }{\tilde{F}}^{\mu \nu }$. In the present work we study the non-Gaussianities and the spectrum of tensor modes generated in this scenario. The non-Gaussianities turn out to be compatible with current observations and can be large enough to be detectable by Planck. The nonobservation of tensor modes imposes new constraints on the parameter space of the system that are about one order of magnitude stronger than those found in our previous paper. More importantly, in certain regions of the parameter space, tensor modes might be detected by upcoming cosmic microwave background (CMB) experiments even if inflation occurs at energies as low as the TeV scale. In this case the tensor modes would be chiral, and would lead to distinctive parity-violating correlation functions in the CMB.

We discuss two Lagrangian interacting dark energy models in the context of the holographic principle. The potentials of the interacting fields are constructed. The models are compared with CMB distance information, baryonic acoustic oscillations, lookback time and the Constitution supernovae sample. For both models, the results are consistent with a nonvanishing interaction in the dark sector of the Universe and the sign of coupling is consistent with dark energy decaying into dark matter, alleviating the coincidence problem—with more than 3 standard deviations of confidence for one of them. However, this is because the noninteracting holographic dark energy model is a bad fit to the combination of data sets used in this work as compared to the cosmological constant with cold dark matter model, so that one needs to introduce the interaction in order to improve this model.

Electromagnetic radiation from superconducting cosmic string loops can reionize neutral hydrogen in the Universe at very early epochs, and affect the cosmic microwave background temperature and polarization correlation functions at large angular scales. We constrain the string tension and current using WMAP7 data, and compare with earlier constraints that employed cosmic microwave background spectral distortions. Over a wide range of string tensions, the current on the string has to be less than $\sim {10}^7\mathrm{GeV}$.

We point out that the metrics recently proposed [K. Balasubramanian and J. McGreevy, arXiv:1111.0634] as gravitational duals to Lifshitz Chern-Simons gauge theories contain both a hidden null singularity and a region of closed timelike curves accessible to asymptotic observers. Like the singularity in the original Liftshitz spacetime given by Kachru, Liu, and Mulligan, this singularity does not include large ${\alpha }^{\prime }$ or $g_s$ corrections and hence appears to be singular in string theory as well as classically.