Two methods are employed to measure the neutrino flux of the antineutrino-mode beam observed by the MiniBooNE detector. The first method compares data to simulated event rates in a high-purity ${\nu }_{\mu }$-induced charged-current single ${\pi }^{+}$ ($\mathrm{CC}1{\pi }^{+}$) sample while the second exploits the difference between the angular distributions of muons created in ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$ charged-current quasielastic (CCQE) interactions. The results from both analyses indicate the prediction of the neutrino flux component of the predominately antineutrino beam is overestimated—the $\mathrm{CC}1{\pi }^{+}$ analysis indicates the predicted ${\nu }_{\mu }$ flux should be scaled by $0.76\pm 0.11$, while the CCQE angular fit yields $0.65\pm 0.23$. The energy spectrum of the flux prediction is checked by repeating the analyses in bins of reconstructed neutrino energy, and the results show that the spectral shape is well-modeled. These analyses are a demonstration of techniques for measuring the neutrino contamination of antineutrino beams observed by future nonmagnetized detectors.

We present a new framework for defining fuzzy approximations to geometry in terms of a cutoff on the spectrum of the Dirac operator, and a generalization of it that we call the Dirac-flux operator. This framework does not require a symplectic form on the manifold, and is completely rotation invariant on an arbitrary $n$-sphere. The framework is motivated by the formalism of holographic space-time, whose fundamental variables are sections of the spinor bundle over a compact Euclidean manifold. The strong holographic principle requires the space of these sections to be finite dimensional. We discuss applications of fuzzy spinor geometry to holographic space-time and to matrix theory.

In this paper, we investigate the $Q$-ball Ansatz in the baby Skyrme model. First, the appearance of peakons, i.e. solutions with extremely large absolute values of the second derivative at maxima, is analyzed. It is argued that such solutions are intrinsic to the baby Skyrme model and do not depend on the detailed form of a potential used in calculations. Next, we concentrate on compact nonspinning $Q$-balls. We show the failure of a small parameter expansion in this case. Finally, we explore the existence and parameter dependence of $Q$-ball solutions.

The standard axionlike particle explanation of the observed large-scale coherent orientations of quasar polarization vectors is ruled out by the recent measurements of vanishing circular polarization. We introduce a more general wave-packet formalism and show that, although decoherence effects between waves of different frequencies can reduce significantly the amount of circular polarization, the axionlike particle hypothesis is disfavored given the bandwidth with which part of the observations were performed. Finally, we show that a more sophisticated model of extragalactic fields does not lead to an alignment of polarizations.

In the present work a closed system of kinetic equations is obtained from the truncation of the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy for the description of the vacuum creation of an electron-positron plasma and secondary photons due to a strong laser field. This truncation is performed in the Markovian approximation for the one-photon annihilation channel which is accessible due to the presence of the strong external field. Estimates of the photon production rate are obtained for different domains of laser field parameters (frequency $\nu$ and field strength $E$). A huge quantity of optical photons of the quasiclassical laser field is necessary to satisfy the conservation laws of the energy and momentum of the constituents ($e^{-}$, $e^{+}$ and $\gamma$) in this channel. Since the number of these optical photons corresponds to the order of perturbation theory, a vanishingly small photon production rate results for the optical region and strongly subcritical fields $E\ll E_c$. In the $\gamma$-ray region $\nu \lesssim m$ the required number of laser photons is small and the production rate of photons from the one-photon annihilation process becomes accessible to observations for subcritical fields $E\lesssim E_c$. In the infrared region the photon distribution has a $1/k$ spectrum typical for flicker noise.

In this article, we derive the integral equation that controls the momentum dependence of the effective gluon mass in the Landau gauge. This is accomplished by means of a well-defined separation of the corresponding “one-loop dressed” Schwinger-Dyson equation into two distinct contributions, one associated with the mass and one with the standard kinetic part of the gluon. The entire construction relies on the existence of a longitudinally coupled vertex of nonperturbative origin, which enforces gauge invariance in the presence of a dynamical mass. The specific structure of the resulting mass equation, supplemented by the additional requirement of a positive-definite gluon mass, imposes a rather stringent constraint on the derivative of the gluonic dressing function, which is comfortably satisfied by the large-volume lattice data for the gluon propagator, both for $SU(2)$ and $SU(3)$. The numerical treatment of the mass equation, under some simplifying assumptions, is presented for the aforementioned gauge groups, giving rise to a gluon mass that is a nonmonotonic function of the momentum. Various theoretical improvements and possible future directions are briefly discussed.

Classical light-bending is investigated for weak gravitational fields in the presence of hypothetical local Lorentz violation. Using an effective field theory framework that describes general deviations from local Lorentz invariance, we derive a modified deflection angle for light passing near a massive body. The results include anisotropic effects not present for spherical sources in General Relativity as well as Weak Equivalence Principle violation. We develop an expression for the relative deflection of two distant stars that can be used to analyze data in past and future solar-system observations. The measurement sensitivities of such tests to coefficients for Lorentz violation are discussed.

Solutions to the Balitsky-Kovchegov equation are considered which respect an $SO(3)$ subgroup of the conformal group. The symmetry dictates a specific dependence of the saturation scale on the impact parameter. Applications to deep inelastic scattering are considered.

A difficulty with previous treatments of the gravitational self-force is that an explicit formula for the force is available only in a particular gauge (Lorenz gauge), where the force in other gauges must be found through a transformation law once the Lorenz-gauge force is known. For a class of gauges satisfying a “parity condition” ensuring that the Hamiltonian center of mass of the particle is well-defined, I show that the gravitational self-force is always given by the angle average of the bare gravitational force. To derive this result I replace the computational strategy of previous work with a new approach, wherein the form of the force is first fixed up to a gauge-invariant piece by simple manipulations, and then that piece is determined by working in a gauge designed specifically to simplify the computation. This offers significant computational savings over the Lorenz gauge, since the Hadamard expansion is avoided entirely and the metric perturbation takes a very simple form. I also show that the rest mass of the particle does not evolve due to first-order self-force effects. Finally, I consider the “mode sum regularization” scheme for computing the self-force in black hole background spacetimes, and use the angle-average form of the force to show that the same mode-by-mode subtraction may be performed in all parity-regular gauges. It appears plausible that suitably modified versions of the Regge-Wheeler and radiation gauges (convenient to Schwarzschild and Kerr, respectively) are in this class.

The thermodynamics of Myers-Perry black holes in general dimensions are studied using a particle probe. When undergoing particle absorption, the changes of the entropy and irreducible mass are shown to be dependent on the particle radial momentum. The black hole thermodynamic behaviors are dependent on dimensionality for specific rotations. For a 4-dimensional Kerr black hole, its black hole properties are maintained for any particle absorption. 5-dimensional black holes can avoid a naked ring singularity by absorbing a particle in specific momenta ranges. Black holes over 6 dimensions become ultraspinning black holes through a specific form of particle absorption. The microscopical changes are interpreted in limited cases of Myers-Perry black holes using Kerr/CFT correspondence. We systematically describe the black hole properties changed by particle absorption in all dimensions.

The absorption cross section of Reissner-Nordström black holes for the gravitational field is computed numerically, taking into account the coupling of the electromagnetic and gravitational perturbations. Our results are in excellent agreement with low- and high-frequency approximations. We find equality between gravitational and electromagnetic absorption cross sections of extreme Reissner-Nordström black holes for all frequencies, which we explain analytically. This gives the first example of objects in general relativity in four dimensions that absorb the electromagnetic and gravitational waves in exactly the same way.

We argue that the decays of radioactive nuclei related to ${}^{44}\mathrm{Ti}$ and ${}^{56}\mathrm{Ni}$ ejected during supernova explosions can provide a vast pool of mildly relativistic positrons and electrons which are further accelerated to ultrarelativistic energies by reverse and forward shocks. This interesting link between two independent processes—the radioactivity and the particle acceleration—can be a clue for solution of the well known theoretical problem of electron injection in supernova remnants. In the case of the brightest radio source Cas A, we demonstrate that the radioactivity can supply adequate number of energetic electrons and positrons for interpretation of observational data provided that they are stochastically preaccelerated in the upstream regions of the forward and reverse shocks.

So far the squarks have not been detected at the LHC indicating that they are heavier than a few hundred GeVs, if they exist. The lighter stop can be considerably lighter than the other squarks. We study the possibility that a supersymmetric partner of the top quark, stop, is the next-to-lightest supersymmetric particle in the constrained supersymmetric standard model. Various constraints, on top of the mass limits, are taken into an account, and the allowed parameter space for this scenario is determined. Observing stop which is the next-to-lightest supersymmetric particle at the LHC may be difficult.

In this work, we calculate the CP-averaged branching ratios and the polarization fractions of the charmless hadronic $B_c\to A_2{A}_3$ decays within the framework of perturbative QCD (pQCD) approach, where $A$ is either a light ${}^{3}P_1$ or ${}^{1}P_1$ axial-vector meson. These 32 decay modes can occur through the annihilation topology only. Based on the perturbative calculations and phenomenological analysis, we find the following results: (a) the branching ratios of the considered 32 $B_c\to A_2{A}_3$ decays are in the range of ${10}^{-5}$ to ${10}^{-8}$; (b) $B_c\to a_1{b}_1$, ${\overline{K}}_1^0{K}_1^{+}$ and some other decays have sizable branching ratios and can be measured at the LHC experiments; (c) the branching ratios of $B_c\to A_2({}^{1}P_1)A_3({}^{1}P_1)$ decays are generally much larger than those of $B_c\to A_2({}^{3}P_1)A_3({}^{3}P_1)$ decays with a factor around ($10\sim 100$); (d) the branching ratios of $B_c\to {\overline{K}}_1^0{K}_1^{+}$ decays are sensitive to the value of ${\theta }_K$, which will be tested by the running LHC and forthcoming SuperB experiments; (e) the large longitudinal polarization contributions govern most considered decays and play the dominant role.

We present the results of fits of short-baseline neutrino-oscillation data in $3+1$ and $3+2$ neutrino-mixing schemes. In spite of the presence of a tension in the interpretation of the data, $3+1$ neutrino mixing is attractive for its simplicity and for the natural correspondence of one new entity (a sterile neutrino) with a new effect (short-baseline oscillations). The allowed regions in the oscillation parameter space can be tested in near-future experiments. In the framework of $3+2$ neutrino mixing, there is less tension in the interpretation of the data, at the price of introducing a second sterile neutrino. Moreover, the improvement of the parameter goodness of fit is mainly a statistical effect due to an increase in the number of parameters. The $CP$ violation in short-baseline experiments allowed in $3+2$ neutrino mixing can explain the positive ${\overline{\nu }}_{\mu }\to {\overline{\nu }}_e$ signal and the negative ${\nu }_{\mu }\to {\nu }_e$ measurement in the MiniBooNE experiment. For the $CP$-violating phase, we obtained two minima of the marginal ${\chi }^2$ close to the two values where $CP$ violation is maximal.

We use gauge/gravity duality to study simultaneously the mass spectrum and the thermodynamics of a generic quasiconformal gauge theory, specified by its beta function. The beta function of a quasiconformal theory almost vanishes, and the coupling is almost constant between two widely separated energy scales. Depending on whether the gravity dual has a black hole or not, the mass spectrum is either a spectrum of quasinormal oscillations or a normal $T=0$ mass spectrum. The mass spectrum is quantitatively correlated with the thermal properties of the system. As the theory approaches conformality, the masses have to vanish. We show that in this limit, the masses calculated via gauge/gravity duality satisfy expected scaling properties.

We have studied the localization of a scalar field on a 3-brane embedded in a six-dimensional warped bulk of the form $M_4\times C_2$, where $M_4$ is a 3-brane and $C_2$ is a 2-cycle of a six-dimensional resolved conifold ${\mathcal{C}}_6$ over a $T^{1,1}$ space. Since the resolved conifold is singularity-free in $r=0$ depending on a resolution parameter $a$, we have analyzed the behavior of the localization of a scalar field when we vary the resolution parameter. On one hand, this enables us to study the effects that a singularity has on the field. On the other hand we can use the resolution parameter as a fine-tuning between the bulk Planck mass and 3-brane Planck mass and so it opens a new perspective to extend the hierarchy problem. Using a linear and a nonlinear warp factor, we have found that the massive and massless modes are trapped to the brane even in the singular cone ($a\ne 0$). We have also compared the results obtained in this geometry and those obtained in other six-dimensional models, such as stringlike geometry and cigarlike universe geometry.

Using a Kolmogorov turbulence model, we investigate the effects of fluctuations in matter and neutrino density in the region near a supernova core on the flavor oscillations of neutrinos emitted in the core collapse in a single-angle, two-flavor approximation. Deviation from a smooth background neutrino density causes significant alterations in the final flavor state of the neutrino ensemble after 400 km, but even very large fluctuations in the matter density do not strongly affect the state of the neutrinos after the collective phase. In both cases, there is a strong effect on the neutrino flavor evolution at intermediate radii, with the flavor evolution becoming much more chaotic. The effect of fluctuations also depends strongly on the initial neutrino spectra. We conclude that the true neutrino fluxes arriving at Earth from core-collapse supernova could differ considerably from predictions of neutrino fluxes based on approximate models with smoothly decreasing matter and neutrino densities.