We report on a search for the process $B^{+}\to {\overline{K}}^{*0}(892)K^{+}$ using $232\times {10}^6$ $\mathit{{\rm Y}}(4S)\to B\overline{B}$ decays collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at SLAC. From a signal yield of $25\pm 13[\mathrm{stat}]\pm 7[\mathrm{syst}]$ $B^{+}\to {\overline{K}}^{*0}(892)(\to K^{-}{\pi }^{+})K^{+}$ events, we place an upper limit on the branching fraction $\mathcal{B}(B^{+}\to {\overline{K}}^{*0}(892)K^{+})$ of $1.1\times {10}^{-6}$, at the 90% confidence level.

The axion modified electrodynamics is usually used as a model for description of possible violation of Lorentz invariance in field theory. The low-energy manifestation of Lorentz violation can hopefully be observed in experiments with electromagnetic waves. It justifies the importance of studying how a small axion addition can modify the wave propagation. Although a constant axion does not contribute to the dispersion relation at all, even a slowly varying axion field destroys the light cone structure. In this paper, we study the wave propagation in the axion modified electrodynamics in the framework of the premetric approach. In addition to the modified dispersion relation, we derive the axion generalization of the photon propagator in Feynman and Landau gauge. Our consideration is free of the usual restriction to the constant gradient axion field. It is remarkable that the axion modified propagator is Hermitian. Consequently, the dissipation effects are absent even in the phenomenological model considered here.

In this work we extend and apply a previous proposal to study noncommutative cosmology to the Friedmann-Robertson-Walker cosmological background coupled to a scalar field. This is done in classical and quantum scenarios. In both cases noncommutativity is introduced in the gravitational field as well as in the scalar field through a deformation of minisuperspace, and we are able to find exact solutions. Finally, the effects of noncommutativity on the classical evolution are analyzed.

We present explicit expressions for the conformal Killing-Yano tensors for the Plebański-Demiański family of type D solutions in four dimensions. Some physically important special cases are discussed in more detail. In particular, it is demonstrated how the conformal Killing-Yano tensor becomes the Killing-Yano tensor for the solutions without acceleration. A possible generalization into higher dimensions is studied. Whereas the transition from the nonaccelerating to accelerating solutions in four dimensions is achieved by the conformal rescaling of the metric, we show that such a procedure is not sufficiently general in higher dimensions—only the maximally symmetric spacetimes in “accelerated” coordinates are obtained.

A special test electromagnetic field in the spacetime of the higher-dimensional generally rotating NUT–(anti-)de Sitter black hole is found. It is adjusted to the hidden symmetries of the background represented by the principal Killing-Yano tensor. Such an electromagnetic field generalizes the field of charged black hole in four dimensions. In higher dimensions, however, the gravitational backreaction of such a field cannot be consistently solved.

In [Phys. Rev. Lett. 98, 061102 (2007)], we announced the complete integrability of geodesic motion in the general higher-dimensional rotating black-hole spacetimes. In the present paper we prove all the necessary steps leading to this conclusion. In particular, we demonstrate the independence of the constants of motion and the fact that they Poisson commute. The relation to a different set of constants of motion constructed in [J. High Energy Phys. 02 (2007) 004] is also briefly discussed.

“Einstein–aether” theory is a generally covariant theory of gravity containing a dynamical preferred frame. This article continues an examination of effects on the motion of binary pulsar systems in this theory, by incorporating effects due to strong fields in the vicinity of neutron star pulsars. These effects are included through an effective approach, by treating the compact bodies as point particles with nonstandard, velocity dependent interactions parametrized by dimensionless sensitivities. Effective post-Newtonian equations of motion for the bodies and the radiation damping rate are determined. More work is needed to calculate values of the sensitivities for a given fluid source; therefore, precise constraints on the theory’s coupling constants cannot yet be stated. It is shown, however, that strong field effects will be negligible given current observational uncertainties if the dimensionless couplings are less than roughly 0.1 and two conditions that match the PPN parameters to those of pure general relativity are imposed. In this case, weak field results suffice. There then exists a one-parameter family of Einstein–aether theories with “small-enough” couplings that passes all current observational tests. No conclusion can be reached for larger couplings until the sensitivities for a given source can be calculated.

We present a study of spinning black hole binaries focusing on the spin dynamics of the individual black holes as well as on the gravitational recoil acquired by the black hole produced by the merger. We consider two series of initial spin orientations away from the binary orbital plane. In one of the series, the spins are antialigned; for the second series, one of the spins points away from the binary along the line separating the black holes. We find a remarkable agreement between the spin dynamics predicted at 2nd post-Newtonian order and those from numerical relativity. For each configuration, we compute the kick of the final black hole. We use the kick estimates from the series with antialigned spins to fit the parameters in the Kidder kick formula, and verify that the recoil in the direction of the orbital angular momentum is $\propto \sin \theta$ and on the orbital plane $\propto \cos \theta$, with $\theta$ the angle between the spin directions and the orbital angular momentum. We also find that the black hole spins can be well estimated by evaluating the isolated horizon spin on spheres of constant coordinate radius.

We study the cosmological evolution of extended branes in 6D warped flux compactification models. The branes are endowed with the three ordinary spatial dimensions, which are assumed to be homogeneous and isotropic, as well as an internal extra dimension compactified on a circle. We embed these codimension 1 branes in a static bulk 6D spacetime, whose geometry is a solution of 6D Einstein-Maxwell or Einstein-Maxwell-dilaton theories, corresponding to a warped flux compactification. The brane matter consists of a complex scalar field which is coupled to the bulk $U(1)$ gauge field. In both models, we show that there is critical point which the brane cannot cross as it moves in the bulk. We study the cosmological behavior, especially when the brane approaches this critical point or one of the two conical singularities. In the present setup where the bulk geometry is fixed, we find that the brane cosmology does not coincide with the standard one in the low-energy limit.

A vectorlike colorless fermion doublet and a singlet added to the standard model allow a consistent interpretation of dark matter in terms of the lightest neutral particle, as they may help in obtaining successful gauge coupling unification. We analyze in detail the mass range of the lightest neutral particle below the $W$ mass, i.e. in a range of the parameters where the physics of the standard model Higgs boson may be substantially affected either directly or indirectly.

Cosmological backreaction has been suggested as an explanation of dark energy and is heavily disputed since. We combine cosmological perturbation theory with Buchert’s nonperturbative framework, calculate the relevant averaged observables up to second order in the comoving synchronous gauge, and discuss their gauge dependence. With the help of an integrability condition, the leading second order contributions follow from the first order calculation. We focus on the onset of cosmological backreaction, as a perturbative treatment is necessarily restricted to the era when the effect is still small. We demonstrate that the leading contributions to all averaged physical observables are completely specified on the boundary of the averaged domain. For any finite domain, these surface terms are nonzero in general and thus backreaction is for real. We map the backreaction effect on an effectively homogeneous and isotropic fluid. The generic effective equation of state is not only time dependent, but also depends on scale.

A model of the Universe with a small eccentricity due to the presence of a magnetic field at the decoupling time (i.e., an ellipsoidal universe) has been recently proposed for the solution of the low quadrupole anomaly of the angular power spectrum of cosmic microwave background anisotropies. We present a complete statistical analysis of that model showing that the probability of increasing of the amplitude of the quadrupole is larger than the probability of decreasing in the whole parameters’ space.

The origin of the ultrahigh-energy (UHE) cosmic rays (CRs) from the second knee ($\sim 6\times {10}^{17}\mathrm{eV}$) above in the CR spectrum is still unknown. Recently, there has been growing evidence that a peculiar type of supernovae, called hypernovae, are associated with subenergetic gamma-ray bursts, such as SN1998bw/GRB980425 and SN2003lw/GRB031203. Such hypernovae appear to have high (up to mildly relativistic) velocity ejecta, which may be linked to the subenergetic gamma-ray bursts. Assuming a continuous distribution of the kinetic energy of the hypernova ejecta as a function of its velocity $E_k\propto (\Gamma \beta {)}^{-\alpha }$ with $\alpha \sim 2$, we find that (1) the external shock wave produced by the high-velocity ejecta of a hypernova can accelerate protons up to energies as high as ${10}^{19}\mathrm{eV}$; (2) the cosmological hypernova rate is sufficient to account for the energy flux above the second knee; and (3) the steeper spectrum of CRs at these energies can arise in these sources. In addition, hypernovae would also give rise to a faint diffuse UHE neutrino flux, due to $p\gamma$ interactions of the UHE CRs with hypernova optical-UV photons.

Energies for excited isospin $I=\frac{1}{2}$ and $I=\frac{3}{2}$ states that include the nucleon and $\Delta$ families of baryons are computed using quenched, anisotropic lattices. Baryon interpolating field operators that are used include nonlocal operators that provide $G_2$ irreducible representations of the octahedral group. The decomposition of spin $\frac{5}{2}$ or higher spin states is realized for the first time in a lattice QCD calculation. We observe patterns of degenerate energies in the irreducible representations of the octahedral group that correspond to the subduction of the continuum spin $\frac{5}{2}$ or higher. The overall pattern of low-lying excited states corresponds well to the pattern of physical states subduced to the irreducible representations of the octahedral group.

One of the most important tasks in high energy physics is the search for the exotic states, such as glueball, hybrid, and multiquark states. The transitions $\psi (ns)\to \psi (ms)+\pi \pi$ and ${\rm Y}(ns)\to {\rm Y}(ms)+\pi \pi$ attract great attention because they may reveal characteristics of hybrids. In this work, we analyze those transition modes in terms of the theoretical framework established by Yan and Kuang. It is interesting to notice that the intermediate states between the two gluon emissions are hybrids, therefore by fitting the data, we are able to determine the mass spectra of hybrids. The ground hybrid states are predicted as 4.23 GeV (for charmonium) and 10.79 GeV (for bottonium) which do not correspond to any states measured in recent experiments, thus it may imply that, very possibly, hybrids mix with regular quarkonia to constitute physical states. Comprehensive comparisons of the potentials for hybrids whose parameters are obtained in this scenario with the lattice results are presented.

The experimental results obtained in the last few years on kaon decays ($K\to 2\pi$ and, above all, Ke4 decays) allow a reliable, model-independent determination of low energy $\pi \pi$ scattering in the S0 wave. Using them and, eventually, other sets of data, it is possible to give a precise parametrization of the S0 wave as well as to find the scattering length and effective range parameter. One can also perform an extrapolation to the pole of the “sigma resonance” [$f_0(600)$]. We obtain the results $a_0^{(0)}=0.233\pm 0.013M_{\pi }^{-1}$, $b_0^{(0)}=0.285\pm 0.012M_{\pi }^{-3}$, and, for the sigma pole, $M_{\sigma }=484\pm 17\mathrm{MeV}$, ${\Gamma }_{\sigma }/2=255\pm 10\mathrm{MeV}$.

The signatures of sterile neutrinos in the supernova neutrino signal in megaton water Cerenkov detectors are studied. Time dependent modulation of the neutrino signal emerging from the sharp changes in the oscillation probability due to shock waves is shown to be a smoking gun for the existence of sterile neutrinos. These modulations and indeed the entire neutrino oscillation signal is found to be different for the case with just three active neutrinos and the cases where there are additional sterile species mixed with the active neutrinos. The effect of turbulence is taken into account and it is found that the effect of the shock waves, while modified, remains significant and measurable. Supernova neutrino signals in water detectors can therefore give unambiguous proof for the existence of sterile neutrinos, the sensitivity extending beyond that for terrestrial neutrino experiments. In addition the time dependent modulations in the signal due to shock waves can be used to trace the evolution of the shock wave inside the supernova.

We study the problem of determination of the sign of $\Delta m_{31}^2$, or the neutrino mass hierarchy, through observations of atmospheric neutrinos in future detectors. We consider two proposed detector types: (a) Megaton sized water C̆erenkov detectors, which can measure the event rates of ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ and ${\nu }_e+{\overline{\nu }}_e$ and (b) 100 kton sized magnetized iron detectors, which can measure the event rates of ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$. For energies and path lengths relevant to atmospheric neutrinos, these rates obtain significant matter contributions from $P_{\mu e}$, $P_{\mu \mu }$ and $P_{ee}$, leading to an appreciable sensitivity to the hierarchy. We do a binned ${\chi }^2$ analysis of simulated data in these two types of detectors which includes the effect of smearing in neutrino energy and direction and incorporates detector efficiencies and relevant statistical, theoretical and systematic errors. We also marginalize the ${\chi }^2$ over the allowed ranges of neutrino parameters in order to accurately account for their uncertainties. Finally, we compare the performance of both types of detectors vis a vis the hierarchy determination.

We search for direct pair production of supersymmetric top quarks and supersymmetric bottom quarks in proton-antiproton collisions at $\sqrt{s}=1.96\mathrm{TeV}$, using $295{\mathrm{pb}}^{-1}$ of data recorded by the Collider Detector at Fermilab (CDF II) experiment. The supersymmetric top (supersymmetric bottom) quarks are selected by reconstructing their decay into a charm (bottom) quark and a neutralino, which is assumed to be the lightest supersymmetric particle. The signature of such processes is two energetic heavy-flavor jets and missing transverse energy. The number of events that pass our selection for each search process is consistent with the expected standard model background. By comparing our results to the theoretical production cross sections of the supersymmetric top and supersymmetric bottom quarks in the minimal supersymmetric standard model, we exclude, at a 95% confidence level in the frame of that model, a supersymmetric top quark mass up to $132\mathrm{GeV}/c^2$ for a neutralino mass of $48\mathrm{GeV}/c^2$, and a supersymmetric bottom quark mass up to $193\mathrm{GeV}/c^2$ for a neutralino mass of $40\mathrm{GeV}/c^2$.