Within the “pseudo-Dirac” scenario for massive neutrinos the existence of sterile neutrinos which are almost degenerate in mass with the active ones is hypothesized. The presence of these sterile neutrinos can affect the flavor composition of cosmic neutrinos arriving at Earth after traveling large distances from astrophysical objects. We examine the prospects of neutrino telescopes such as IceCube to probe the very tiny mass squared differences ${10}^{-12}{\mathrm{eV}}^2>\Delta m^2>{10}^{-19}{\mathrm{eV}}^2$, by analyzing the ratio of $\mu$-track events to showerlike events. Considering various sources of uncertainties which enter this analysis, we examine the capability of neutrino telescopes to verify the validity of the pseudo-Dirac neutrino scenario and especially to discriminate it from the conventional scenario with no sterile neutrino. We also discuss the robustness of our results with respect to the uncertainties in the initial flavor ratio of neutrinos at the source.

We construct general models for holographic superconductivity parametrized by three couplings which are functions of a real scalar field and show that under general assumptions they describe superconducting phase transitions. While some features are universal and model independent, important aspects of the quantum critical behavior strongly depend on the choice of couplings, such as the order of the phase transition and critical exponents of second-order phase transitions. In particular, we study a one-parameter model where the phase transition changes from second to first order above some critical value of the parameter and a model with tunable critical exponents.

We consider a real massless scalar field inside a cavity with a moving mirror in a two-dimensional spacetime, satisfying the Dirichlet or Neumann boundary condition at the instantaneous position of the boundaries, for an arbitrary and relativistic law of motion. Considering an arbitrary initial field state, we show that the exact value of the energy density in the cavity can be obtained by tracing back a sequence of null lines, connecting the value of the energy density at the given spacetime point to a certain known value of the energy density at a point in the region where the initial field modes are not affected by the boundary motion. We obtain the particular formulas for the energy density of the field and the quantum force acting on the boundaries for a vacuum, thermal, and a coherent state. We thus generalize a previous result in literature [17], where this problem is approached for only one mirror. For the particular cases of vacuum and Dirichlet boundary condition, nonrelativistic velocities, or in the limit of large length of the cavity, our results coincide with those found in the literature.

We show that the averaged null energy condition can be violated by a conformally coupled scalar field in a conformally flat spacetime in $3+1$ dimensions. The violation is dependent on the quantum state and can be made as large as desired. It does not arise from the presence of anomalies, although anomalous violations are also possible. Since all geodesics in conformally flat spacetimes are achronal, the achronal averaged null energy condition is likewise violated.

A null line is a complete achronal null geodesic. It is proven that for any quantum fields minimally coupled to semiclassical Einstein gravity, the averaged null energy condition (ANEC) on null lines is a consequence of the generalized second law of thermodynamics for causal horizons. This result is shown to leading order in Planck’s constant for perturbations to classical backgrounds satisfying the null energy condition. Auxiliary assumptions include CPT and the existence of a suitable renormalization scheme for the generalized entropy. Although the ANEC can be violated on general geodesics in curved spacetimes, as long as the ANEC holds on null lines there exist theorems showing that semiclassical gravity should satisfy positivity of energy, topological censorship, and should not admit closed timelike curves. It is pointed out that these theorems fail once the linearized graviton field is quantized, because then the renormalized shear-squared term in the Raychaudhuri equation can be negative. A “shear-inclusive” generalization of the ANEC is proposed to remedy this, and is proven under an additional assumption about perturbations to horizons in classical general relativity.

We study fluctuations of conserved charges including baryon number, electric charge, and strangeness as well as the correlations among these conserved charges in the $2+1$ flavor Polyakov–Nambu–Jona-Lasinio model at finite temperature. The calculated results are compared with those obtained from recent lattice calculations performed with an improved staggered fermion action at two values of the lattice cutoff with almost physical up and down quark masses and a physical value for the strange quark mass. We find that our calculated results are well consistent with those obtained in lattice calculations except for some quantitative differences for fluctuations related with strange quarks. Our calculations indicate that there is a pronounced cusp in the ratio of the quartic to quadratic fluctuations of baryon number, i.e. ${\chi }_4^B/{\chi }_2^B$, at the critical temperature during the phase transition, which confirms that ${\chi }_4^B/{\chi }_2^B$ is a useful probe of the deconfinement and chiral phase transition.

We consider a holographic model constructed from the intersecting brane configuration $\mathrm{D}4\mathrm{\text{−}}\overline{\mathrm{D}4}/\mathrm{D}4$ in noncritical string theory. We study the chiral phase diagram of this holographic QCD-like model with a finite baryon chemical potential through the supergravity dual approximation.

We holographically engineer a periodic lattice of localized fermionic impurities within a plasma medium by putting an array of probe D5-branes in the background produced by $N$ D3-branes. Thermodynamic quantities are computed in the large $N$ limit via the holographic dictionary. We then dope the lattice by replacing some of the D5-branes by anti-D5-branes. In the large $N$ limit, we determine the critical temperature below which the system dimerizes with bond ordering. Finally, we argue that for the special case of a square lattice our system is glassy at large but finite $N$, with the low temperature physics dominated by a huge collection of metastable dimerized configurations without long-range order, connected only through tunneling events.

Within the framework of the ($3+1$)-dimensional Lorentz-violating extended electrodynamics including the CPT-odd Chern-Simons term, we consider the electromagnetic field between two parallel perfectly conducting plates. We find the one-particle eigenstates of such a field, as well as the implicit expression for the photon energy spectrum. We also show that the tachyon-induced vacuum instability is negligible when the separation between the plates is sufficiently small though finite. In order to find the leading Chern-Simons correction to the vacuum energy, we renormalize and evaluate the sum over all one-particle eigenstate energies using the two different methods, the zeta function technique and the transformation of the discrete sum into a complex plane integral via the residue theorem. The resulting correction to the Casimir force, which is attractive and quadratic in the Chern-Simons term, disagrees with the one obtained in [M. Frank and I. Turan, Phys. Rev. D 74, 033016 (2006)], using the misinterpreted equations of motion. Compared with experimental data, our result places a constraint on the absolute value of the Chern-Simons term.

Seven different refinements of trapped surfaces are proposed, each intended as potential stability conditions. This article concerns spherical symmetry, but each condition can be generalized. Involute trapped spheres satisfy a similar condition to minimal trapped spheres, which are strictly minimal with respect to the Kodama vector. There is also a weaker version of involute trapped spheres. Outer trapped spheres have positive surface gravity. Increasingly (future, respectively, past) trapped spheres generate spheres which are more trapped in a (future, respectively, past) causal direction, with three types: in any such causal direction, along the dual Kodama vector, and in some such causal direction. Assuming the null energy condition, the seven conditions form a strict hierarchy, in the above order. In static space-times, they reduce to three inequivalent definitions, namely, minimal, outer, and increasingly trapped spheres. For a widely considered class of so-called nice (or nondirty) black holes, minimal trapped and outer trapped become equivalent. Reissner-Nordström black holes provide examples of this, and that the increasingly trapped differs. Examples where all three refinements differ are provided by a simple family of dirty black holes parametrized by mass and singularity area.

Decaying dark matter particles could be indirectly detected as an excess over a simple power law in the energy spectrum of the diffuse extragalactic gamma-ray background. Furthermore, since the Earth is not located at the center of the Galactic dark matter halo, the exotic contribution from dark matter decay to the diffuse gamma-ray flux is expected to be anisotropic, offering a complementary method for the indirect search for decaying dark matter particles. In this paper we discuss in detail the expected dipolelike anisotropies in the dark matter signal, taking also into account the radiation from inverse Compton scattering of electrons and positrons from dark matter decay. A different source for anisotropies in the gamma-ray flux are the dark matter density fluctuations on cosmic scales. We calculate the corresponding angular power spectrum of the gamma-ray flux and comment on observational prospects. Finally, we calculate the expected anisotropies for the decaying dark matter scenarios that can reproduce the electron/positron excesses reported by PAMELA and the Fermi LAT, and we estimate the prospects for detecting the predicted gamma-ray anisotropy in the near future.

The GammeV experiment has constrained the couplings of chameleon scalar fields to matter and photons. Here, we present a detailed calculation of the chameleon afterglow rate underlying these constraints. The dependence of GammeV constraints on various assumptions in the calculation is studied. We discuss the GammeV-CHameleon Afterglow SEarch, a second-generation GammeV experiment, which will improve upon GammeV in several major ways. Using our calculation of the chameleon afterglow rate, we forecast model-independent constraints achievable by GammeV-CHameleon Afterglow SEarch. We then apply these constraints to a variety of chameleon models, including quartic chameleons and chameleon dark energy models. The new experiment will be able to probe a large region of parameter space that is beyond the reach of current tests, such as fifth force searches, constraints on the dimming of distant astrophysical objects, and bounds on the variation of the fine structure constant.

Two-body hadronic weak decays of $B_c$ meson involving tensor meson in the final state are studied by using the Isgur-Scora-Grinstein-Wise II model. Decay amplitudes are obtained using the factorization scheme in the spectator quark model. Branching ratios for the charm changing and bottom changing decay modes are predicted.

MiniBooNE reports the first absolute cross sections for neutral current single ${\pi }^0$ production on ${\mathrm{CH}}_2$ induced by neutrino and antineutrino interactions measured from the largest sets of NC ${\pi }^0$ events collected to date. The principal result consists of differential cross sections measured as functions of ${\pi }^0$ momentum and ${\pi }^0$ angle averaged over the neutrino flux at MiniBooNE. We find total cross sections of $(4.76\pm {0.05}_{\mathrm{stat}}\pm {0.76}_{\mathrm{sys}})\times {10}^{-40}{\mathrm{cm}}^2/\mathrm{\text{nucleon}}$ at a mean energy of $⟨E_{\nu }⟩=808\mathrm{MeV}$ and $(1.48\pm {0.05}_{\mathrm{stat}}\pm {0.23}_{\mathrm{sys}})\times {10}^{-40}{\mathrm{cm}}^2/\mathrm{\text{nucleon}}$ at a mean energy of $⟨E_{\nu }⟩=664\mathrm{MeV}$ for ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$ induced production, respectively. In addition, we have included measurements of the neutrino and antineutrino total cross sections for incoherent exclusive NC $1{\pi }^0$ production corrected for the effects of final state interactions to compare to prior results.

We study the masses of the Higgs bosons in the most general two-Higgs-doublet model in a basis-independent approach. We adapt the recently developed Minkowski-space formalism to this problem and calculate traces of any power of the mass matrix in a compact and reparametrization-invariant form. Our results can be used to gain insight into the dynamics of the scalar sector of the general two-Higgs-doublet model.

A recent update of data on the decays of $D^0$, $D^{+}$, and $D_s^{+}$ to pairs of light pseudoscalars calls for a renewed analysis of key decay amplitudes and tests of flavor symmetry. The present data change our previous understanding of relative phases between amplitudes that describe Cabibbo-favored decays of the charmed mesons. The new data also seem to favor a smaller octet-singlet mixing angle for the $\eta$ and ${\eta }^{\prime }$ mesons when singly Cabibbo-suppressed processes are taken into account. We also discuss the effects of the new data on interference between Cabibbo-favored and doubly Cabibbo-suppressed decays.

It is shown that it is possible to perform a model-independent extraction of the Cabibbo-Kobayashi-Maskawa unitarity triangle angle $\gamma$ using only the decays $B^0\to D{K}^{+}{\pi }^{-}$ with $D\to K_S^0{\pi }^{+}{\pi }^{-}$ and $B^0\to D{K}^{+}{\pi }^{-}$ with flavor-specific $D$ decays. The proposed method can also utilize the $B^0\to D{K}^{+}{\pi }^{-}$ data with $CP$-eigenstate decays of the $D$ meson in a model-independent way.

A soft-wall anti–de Sitter/QCD model with a modified five-dimensional metric at the infrared region is constructed to obtain a nontrivial dilaton solution, which incorporates the chiral symmetry breaking and linear confinement. By taking the pion mass and decay constant as two input mass scales, the resulting predictions for the resonance states of pseudoscalar, scalar, vector, and axial-vector mesons agree remarkably with the experimentally confirmed resonance states. The effects of the quartic interaction term are investigated by taking an appropriate sign and magnitude for maintaining the stability of the bulk scalar potential. It is shown that such a simply modified soft-wall anti–de Sitter/QCD model can lead to a consistent prediction for the mass spectra of resonance states in the pseudoscalar, scalar, vector, and axial-vector mesons; the agreement with the experimental data is found to be better than 10% for the excited meson states. The resulting pion form factor also agrees well with the experimental data.

It has recently been proposed that neutrino mass could originate from Yukawa interactions of leptons with new colored particles. This raises the interesting possibility of testing mass generation through copious production of those particles at hadron colliders. A realistic assessment of this, however, should take into account how large those interactions could be, based on available precision results. In this work we make a systematic analysis of the flavor structure in Yukawa couplings, provide a convenient parametrization, and investigate the rare radiative and pure leptonic decays of the muon and tau leptons. For general values of the parameters, the muon decays set stringent constraints on the couplings, and all rare tau decays are far below the current experimental sensitivity. However, there is room in parameter space in which the muon decays could be significantly suppressed by destructive interference between colored particles without generically reducing the couplings themselves. This is also the region of parameters that is relevant to collider physics. We show that for this part of parameter space some tau decays can reach or are close to the current level of precision.

We present a study of the inclusive $D^{*\pm }$ production in the decay of $\mathit{{\rm Y}}(1S)$ using $(98.6\pm 0.9)\times {10}^6$ $\mathit{{\rm Y}}(2S)$ mesons collected with the BABAR detector at the $\mathit{{\rm Y}}(2S)$ resonance. Using the decay chain $\mathit{{\rm Y}}(2S)\to {\pi }^{+}{\pi }^{-}\mathit{{\rm Y}}(1S)$, $\mathit{{\rm Y}}(1S)\to D^{*\pm }X$, where $X$ is unobserved, we measure the branching fraction $\mathcal{B}[\mathit{{\rm Y}}(1S)\to D^{*\pm }X]=(2.52\pm 0.13(\mathrm{stat})\pm 0.15(\mathrm{syst}))\%$ and the $D^{*\pm }$ momentum distribution in the rest frame of the $\mathit{{\rm Y}}(1S)$. We find evidence for an excess of $D^{*\pm }$ production over the expected rate from the virtual photon annihilation process $\mathit{{\rm Y}}(1S)\to {\gamma }^{*}\to c\overline{c}\to D^{*\pm }X$.