We present a search for core-collapse supernovae in the Milky Way galaxy, using the MiniBooNE neutrino detector. No evidence is found for core-collapse supernovae occurring in our Galaxy in the period from December 14, 2004 to July 31, 2008, corresponding to 98% live time for collection. We set a limit on the core-collapse supernova rate out to a distance of 13.4 kpc to be less than 0.69 supernovae per year at 90% C.L.

Previous solar system constraints of the Brans-Dicke (BD) parameter $\omega$ have either ignored the effects of the scalar field potential (mass terms) or assumed a highly massive scalar field. Here, we interpolate between the above two assumptions and derive the solar system constraints on the BD parameter $\omega$ for any field mass. We show that for $\omega =O(1)$ the solar system constraints relax for a field mass $m\gtrsim 20\times m_{\mathrm{AU}}=20\times {10}^{-27}\mathrm{GeV}$.

In this work we study the generalization of twisted homology to geometric and nongeometric backgrounds. In the process, we describe the necessary conditions to wrap a network of D-branes on twisted cycles. If the cycle is localized in time, we show how by an instantonic brane mediation, some D-branes transform into fluxes on different backgrounds, including nongeometric fluxes. As a consequence, we show that in the case of a IIB six-dimensional torus compactification on a simple orientifold, the flux superpotential is not invariant by this brane-flux transition, allowing the connection among different Minkowski vacuum solutions. For the case in which nongeometric fluxes are turned on, we also discuss some topological restrictions for the transition to occur. In this context, we show that there are some vacuum solutions protected to change by a brane-flux transition.

We study the effects of finite chemical potential and impurity scattering on dynamical fermion mass generation in $(2+1)$-dimensional quantum electrodynamics. In any realistic systems, these effects usually cannot be neglected. The longitudinal component of the gauge field develops a finite static length produced by chemical potential and impurity scattering, while the transverse component remains long-ranged because of the gauge invariance. Another important consequence of impurity scattering is that the fermions have a finite damping rate, which reduces their lifetime. By solving the Dyson-Schwinger equation for the fermion mass function, it is found that these effects lead to strong suppression of the critical fermion flavor $N_c$ and the dynamical fermion mass in the symmetry broken phase.

We compute the ratio of the coefficient of shear viscosity to entropy density at finite coupling and at zero chemical potential using holographic duality, up to ten derivative terms in the low energy effective five-dimensional action, of a specific kind, which may or may not be connected to the supersymmetric completion of type IIB theory. The result suggests that this ratio can be positive only for the 8th derivative term even with the form of that term in the action as $\mathcal{C}^{ij}{}_{kl}\mathcal{C}^{kl}{}_{mn}\mathcal{C}^{mn}{}_{rs}\mathcal{C}^{rs}{}_{ij}$, where $\mathcal{C}$ is the Weyl tensor.

We study the stability of $D\ge 7$ asymptotically flat black holes rotating in a single two-plane against tensor-type gravitational perturbations. The extensive search of quasinormal modes for these black holes did not indicate any presence of growing modes, implying the stability of simply rotating Myers-Perry black holes against tensor-type perturbations.

We study Hořava-Lifshitz gravity in the presence of a scalar field. When the detailed balance condition is implemented, a new term in the gravitational sector is added in order to maintain ultraviolet stability. The four-dimensional theory is of a scalar-tensor type with a positive cosmological constant and gravity is nonminimally coupled with the scalar and its gradient terms. The scalar field has a double-well potential and, if required to play the role of the inflation, can produce a scale-invariant spectrum. The total action is rather complicated, and there is no analog of the Einstein frame where Lorentz invariance is recovered in the infrared. For these reasons it may be necessary to abandon detailed balance. We comment on open problems and future directions in anisotropic critical models of gravity.

In this paper we seek static spherically symmetric solutions of Hořava-Lifshitz-like gravity with the projectability condition. We consider the most general form of gravity action without detailed balance, and require the spacetime metric to respect the projectability condition. We find that for any value of $\lambda$, the solutions of topology $\mathbb{R}\times {\mathbb{M}}_3$ may exist, where $\mathbb{R}$ is the time direction and ${\mathbb{M}}_3$ is a three-dimensional maximally symmetric space depending on the value of cosmological constant and the potential of the action. Besides, in the UV region where $\lambda \ne 1$, we find Minkowski or de Sitter spacetime as the solution, while in the IR region where $\lambda =1$, we prove that (dS-)Schwarzschild solution is the only nontrivial solution. We also notice that the other static spherically symmetric solutions found in the literature do not satisfy the projectability condition and are not the solutions we get. Our study shows that in Hořava-Lifshitz gravity with the projectability condition, there is no novel correction to Einstein’s general relativity in solar system tests.

We study the generation of primordial perturbations in a (single-field) slow-roll inflationary Universe. In momentum space, these (Gaussian) perturbations are characterized by a zero mean and a nonzero variance ${\Delta }^2(k,t)$. However, in position space the variance diverges in the ultraviolet. The requirement of a finite variance in position space forces one to regularize ${\Delta }^2(k,t)$. This can (and should) be achieved by proper renormalization in an expanding Universe in a unique way. This affects the predicted scalar and tensorial power spectra (evaluated when the modes acquire classical properties) for wavelengths that today are at observable scales. As a consequence, the imprint of slow-roll inflation on the cosmic microwave background anisotropies is significantly altered. We find a nontrivial change in the consistency condition that relates the tensor-to-scalar ratio $r$ to the spectral indices. For instance, an exact scale-invariant tensorial power spectrum, $n_t=0$, is now compatible with a nonzero ratio $r\approx 0.12\pm 0.06$, which is forbidden by the standard prediction ($r=-8n_t$). The influence of relic gravitational waves on the cosmic microwave background may soon come within the range of planned measurements, offering a nontrivial test of the new predictions.

We systematically study the unification of gauge couplings in the presence of (one or more) effective dimension-5 operators $cH{G}_{\mu \nu }{G}^{\mu \nu }/4M_{\mathrm{pl}}$, induced into the grand unified theory by gravitational interactions at the Planck scale. These operators alter the usual condition for gauge-coupling unification, which can, depending on the Higgs content $H$ and vacuum expectation value, result in unification at scales $M_X$ significantly different than naively expected. We find nonsupersymmetric models of $SU(5)$ and $SO(10)$ unification, with natural Wilson coefficients $c$, that easily satisfy the constraints from proton decay. Furthermore, gauge-coupling unification at scales as high as the Planck scale seems feasible, possibly hinting at simultaneous unification of gauge and gravitational interactions. In the Appendix we work out the group theoretical aspects of this scenario for $SU(5)$ and $SO(10)$ unified groups in detail; this material is also relevant in the analysis of nonuniversal gaugino masses obtained from supergravity.

We evaluate the cross sections for new heavy fermion production at three Large Hadron Collider energies accurate to next-to-leading order in perturbative quantum chromodynamics. We treat the cases of pair production of heavy quarks via strong interactions, single heavy quark production via electroweak interactions, and the production of heavy leptons. Theoretical uncertainties associated with the choice of the renormalization scale and the parton distribution functions are specified. We derive a simple and useful parametrization of our results which should facilitate phenomenological studies of new physics models that predict new heavy quarks and/or leptons.

We compare three different methods to determine the lattice spacing in lattice QCD and give results from calculations on the MILC ensembles of configurations that include the effect of $u$, $d$, and $s$ sea quarks. It is useful, for ensemble to ensemble comparison, to express the results as giving a physical value for $r_1$, a parameter from the heavy quark potential. Combining the three methods gives a value for $r_1$ in the continuum limit of 0.3133(23)(3) fm. Using the MILC values for $r_0/r_1$, this corresponds to a value for the $r_0$ parameter of 0.4661(38) fm. One of our methods involves using the ${\eta }_s$ to determine the lattice spacing and to tune the $s$-quark mass accurately. We give values for $m_{{\eta }_s}$ [0.6858(40) GeV] and $f_{{\eta }_s}$ [0.1815(10) GeV] needed to implement this. We show that the ${\eta }_s$ method by itself is competitive with the $r_1$ method on an ensemble by ensemble basis and compare the two.

Low-lying $\Lambda$ baryons with spin $1/2$ are analyzed in full (unquenched) lattice QCD. We construct $2\times 2$ cross correlators from flavor SU(3) octet and singlet baryon operators, and diagonalize them so as to extract information of two low-lying states for each parity. The two-flavor $CP$-PACS gauge configurations are used, which are generated in the renormalization-group improved gauge action and the $\mathcal{O}(a)$-improved quark action. Three different $\beta$’s, $\beta =1.80$, 1.95, and 2.10, are employed, whose corresponding lattice spacings are $a=0.2150$, 0.1555, and 0.1076 fm. For each cutoff, we use four hopping parameters, (${\kappa }_{\mathrm{val}},{\kappa }_{\mathrm{sea}}$), which correspond to the pion masses ranging about from 500 MeV to 1.1 GeV. Results indicate that there are two negative-parity $\Lambda$ states nearly degenerate at around 1.6 GeV, while no state as low as $\Lambda (1405)$ is observed. By decomposing the flavor components of each state, we find that the lowest (1st-excited) negative-parity state is dominated by flavor-singlet (flavor-octet) component. We also discuss meson-baryon components of each state, which has drawn considerable attention in the context of multiquark pictures of $\Lambda (1405)$.

Predictions for the transverse single spin asymmetry (SSA), $A_N$, are given for the inclusive processes $l{p}^{\uparrow }\to hX$ and $l{p}^{\uparrow }\to \mathrm{\text{jet}}+X$, which could be measured in operating or future experiments. These estimates are based on the Sivers distributions and the Collins fragmentation functions which fit the azimuthal asymmetries measured in semi-inclusive deep inelastic scattering (SIDIS) processes ($l{p}^{\uparrow }\to l^{\prime }hX$). The factorization in terms of transverse momentum dependent distribution and fragmentation functions (TMD factorization)—which supplies the theoretical framework in which SIDIS azimuthal asymmetries are analyzed—is assumed to hold also for the $lp\to hX$ inclusive process at large $P_T$. A measurement of $A_N$ would then provide a direct test of the validity of the TMD factorization in this case and would have important consequences for the study and understanding of SSAs in $p{p}^{\uparrow }\to hX$ processes.

The factorization theorem in decays of $B_{(s)}$ mesons to two charmed mesons (both pseudoscalar and vector) can be proved in the leading order in $m_D/m_B$ and ${\Lambda }_{\mathrm{QCD}}/m_D$ expansion. Working in the perturbative QCD approach, we find that the factorizable emission diagrams are dominant. Most of branching ratios we compute agree with the experimental data well, which means that the factorization theorem seems to be reliable in predicting branching ratios for these decays. In the decays of a $B$ meson to two vector charmed mesons, the transverse polarization states contribute 40%–50% both in the processes with an external $W$ emission and in the pure annihilation decays. This is in agreement with the present experimental data. We also calculate the $CP$ asymmetry parameters. The results show that the direct $CP$ asymmetries are very small. Thus observation of any large direct $CP$ asymmetry will be a signal for new physics. The mixing induced $CP$ asymmetry in the neutral modes is large. This is also in agreement with the current experimental measurements. They can give a cross-check of the $\sin 2\beta$ measurement from other channels.

We present a study of electroweak production of top and antitop quarks in the $s$-channel mode at the LHC, including next-to-leading order QCD corrections to the production and decay of the single (anti)top quark. The spin is preserved in production and decay by using the narrow width approximation for the (anti)top quark. We show the effect of different $O({\alpha }_s)$ contributions on the inclusive cross section and various kinematic distributions at parton level after imposing relevant kinematic cuts to select $s$-channel single top quark events. We also discuss several possibilities for measuring the top quark polarization.

We have performed a dynamical analysis of the mixing in the pseudoscalar channel with the goal of understanding the existence and behavior of the pseudoscalar glueball. Our philosophy has not been to predict precise values of the glueball mass but to exploit an adequate effective theory to the point of breaking and to analyze which kind of mechanisms restore compatibility with data. Our study has led to analytical solutions which allow a clear understanding of the phenomena. The outcome of our calculation leads to a large mass glueball $M_{\Theta }>2000\mathrm{MeV}$, to a large glue content of the ${\eta }^{\prime }$, and to mixing angles in agreement with previous numerical studies.

The SciBooNE Collaboration reports inclusive neutral current neutral pion production by a muon neutrino beam on a polystyrene target (${\mathrm{C}}_8{\mathrm{H}}_8$). We obtain $(7.7\pm 0.5(\mathrm{stat})\pm 0.5(\mathrm{sys}))\times {10}^{-2}$ as the ratio of the neutral current neutral pion production to total charged current cross section; the mean energy of neutrinos producing detected neutral pions is 1.1 GeV. The result agrees with the Rein-Sehgal model implemented in our neutrino interaction simulation program with nuclear effects. The spectrum shape of the ${\pi }^0$ momentum and angle agree with the model. We also measure the ratio of the neutral current coherent pion production to total charged current cross section to be $(0.7\pm 0.4)\times {10}^{-2}$.

We present a study of $B^0\to D_s^{*+}{\pi }^{-}$ and $B^0\to D_s^{*-}{K}^{+}$ decays based on a sample of $657\times {10}^6$ $B\overline{B}$ events collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We measure the branching fractions to be $\mathcal{B}(B^0\to D_s^{*+}{\pi }^{-})=(1.75\pm 0.34(\mathrm{stat})\pm 0.17(\mathrm{syst})\pm 0.11(\mathcal{B}))\times {10}^{-5}$ and $\mathcal{B}(B^0\to D_s^{*-}{K}^{+})=(2.02\pm 0.33(\mathrm{stat})\pm 0.18(\mathrm{syst})\pm 0.13(\mathcal{B}))\times {10}^{-5}$, with significances of 6.1 and 8.0 standard deviations, respectively. The first uncertainty is statistical, the second is due to the experimental systematics, and the third is from uncertainties in the $D_s^{+}$ decay branching fractions. From our measurements, we obtain the most precise determination so far of $R_{D^{*}\pi }$, where $R_{D^{*}\pi }$ is the ratio between amplitudes of the doubly Cabibbo-suppressed decay $B^0\to D^{*+}{\pi }^{-}$ and the Cabibbo-favored $B^0\to D^{*-}{\pi }^{+}$ decay.

We calculate the fundamental quasinormal modes of the Kerr–de Sitter black hole for the first time. In order to calculate the quasinormal modes, we employ the master equations derived by Suzuki, Takasugi, and Umetsu, who transform the Teukolsky equations for the Kerr–de Sitter black hole into the standard form of the Heun’s equation. The transformed functions are expanded around the outer horizon of the black hole or the symmetric axis in the Fröbenius series whose coefficients satisfy a three-term recurrence relation. These three-term recurrence relations allow us to use Leaver’s continued fraction method to calculate the angular separation constant and the quasinormal mode frequency. Any unstable fundamental quasinormal mode is not found in this paper. It is also observed that for some black holes characterized by a large mass parameter, some retrograde modes in the slow rotation limit become prograde as the black hole spin increases. This phenomenon does not occur for the fundamental modes of the Kerr black hole.