We analyze the stress-energy tensor, and the resulting energy conditions, for a scalar field with general curvature coupling, outside a perfectly reflecting sphere with Dirichlet boundary conditions. For conformal coupling we find that the null energy condition is always obeyed, and therefore the averaged null energy condition (ANEC) is also obeyed. Since the ANEC is independent of curvature coupling, we conclude that the ANEC is obeyed for scalar fields with any curvature coupling in this situation. We also show explicitly how the spherical case goes over to that of a flat plate as one approaches the sphere.

One-loop amplitudes of gluons in supersymmetric Yang-Mills are four-dimensional cut-constructible. This means that they can be determined from their unitarity cuts. We present a new systematic procedure to explicitly carry out any finite unitarity cut integral. The procedure naturally separates the contributions from bubble, triangle and box scalar integrals. This technique allows the systematic calculation of $\mathcal{N}=1$ amplitudes of gluons. As an application we compute all next-to-MHV six-gluon amplitudes in $\mathcal{N}=1$ super-Yang-Mills.

The probability for quantum creation of an inflationary universe with a pair of black holes in $1/R$-gravitational theory has been studied. Considering a gravitational action which includes a cosmological constant ($\Lambda$) in addition to $\delta R^{-1}$ term, the probability has been evaluated in a semiclassical approximation with Hartle-Hawking boundary condition. We obtain instanton solutions determined by the parameters $\delta$ and $\Lambda$ satisfying the constraint $\delta \le \frac{4{\Lambda }^2}{3}$. However, we note that two different classes of instanton solutions exists in the region $0<\delta <\frac{4{\Lambda }^2}{3}$. The probabilities of creation of such configurations are evaluated. It is found that the probability of creation of a universe with a pair of black holes is strongly suppressed with a positive cosmological constant except in one case when $0<\delta <{\Lambda }^2$. It is also found that gravitational instanton solution is permitted even with $\Lambda =0$ but one has to consider $\delta <0$. However, in the later case a universe with a pair of black holes is less probable.

Within the framework of geodesic brane gravity, the deviation from general relativity is parametrized by the conserved bulk energy. The corresponding geodesic evolution/nucleation of a de Sitter brane is shown to be exclusively driven by a double-well Higgs potential, rather than by a plain cosmological constant. The (hairy) horizon serves then as the locus of unbroken $Z_2$ symmetry. The quartic structure of the scalar potential, singled out on finiteness grounds of the total (including the dark component) energy density, chooses the Hartle-Hawking no-boundary proposal.

Two leading dark matter candidates from supersymmetry and other theories of physics beyond the standard model are WIMPs and weak scale gravitinos. If the lightest stable particle is a gravitino, then a WIMP will decay into it with a natural lifetime of order a month $\sim M_{\mathrm{pl}}^2/M_{\mathrm{weak}}^3$. We show that if the bulk of dark matter today came from decays of neutral particles with lifetimes of order a year or smaller, then it could lead to a reduction in the amount of small scale substructure, less concentrated halos and constant density cores in the smallest mass halos. Such beneficial effects may therefore be realized naturally, as discussed by Cembranos, Feng, Rajaraman, and Takayama, in the case of supersymmetry.

Magnetic fields in the early Universe could have played an important role in sourcing cosmological perturbations. While not the dominant source, even a small contribution might be traceable through its intrinsic non-Gaussianity. Here we calculate analytically the one-, two-, and three-point statistics of the magnetic stress energy resulting from tangled Gaussian fields, and confirm these with numerical realizations of the fields. We find significant non-Gaussianity, and importantly predict higher order moments that will appear between the scalar, vector, and tensor parts of the stress energy (e.g., scalar-tensor-tensor moments). Such higher order cross correlations are a generic feature of nonlinear theories and could prove to be an important probe of the early Universe.

We study the IR dynamics of the cascading nonconformal quiver theory on $N$ regular and $M$ fractional D3 branes at the tip of the complex cone over the first del Pezzo surface. The horizon of this cone is the irregular Sasaki-Einstein manifold $Y^{2,1}$. Our analysis shows that at the end of the cascade supersymmetry is dynamically broken.

Within the context of modified gravity and dark energy scenarios of the accelerated universe, we study the stability of de Sitter space with respect to inhomogeneous perturbations using a gauge-independent formalism. In modified gravity the stability condition is exactly the same that one obtains from a homogeneous perturbation analysis, while the stability condition in scalar-tensor gravity is more restrictive.

We propose the $K\to \pi \gamma$ decay mode as a signature of the violation of the Lorentz invariance and the appearance of new physics via space-time noncommutativity.

We examine the multiplet structure and decay channels of baryon resonances in the large $N_c$ QCD generalization of the $N_c=3$ SU(6) spin-flavor $\mathbf{70}$. We show that this “$\mathbf{70}$,” while a construct of large $N_c$ quark models, actually consists of five model-independent irreducible spin-flavor multiplets in the large $N_c$ limit. The preferred decay modes for these resonances fundamentally depend upon which of the five multiplets to which the resonance belongs. For example, there exists an SU(3) “$\mathbf{8}$” of resonances that is $\eta$-philic and $\pi$-phobic, and an “$\mathbf{8}$” that is the reverse. Moreover, resonances with a strong SU(3) “$\mathbf{1}$” component prefer to decay via a $\overline{K}$ rather than via a $\pi$. Remarkably, available data appears to bear out these conclusions.

We show three types of neutrino mass textures, which give maximal $CP$ violation as well as maximal atmospheric neutrino mixing. These textures are described by six real mass parameters: one specified by two complex flavor neutrino masses and two constrained ones and the others specified by three complex flavor neutrino masses. In each texture, we calculate mixing angles and masses, which are consistent with observed data, as well as Majorana $CP$ phases.

Grand unified theories can lead to nonuniversal boundary conditions for the gaugino masses at the unification scale. We consider the implications of such nonuniversal boundary conditions for the composition of the lightest neutralino as well as for the upper bound on its mass in the simplest supersymmetric grand unified theory based on the $SU(5)$ gauge group. We derive sum rules for neutralino and chargino masses in different representations of $SU(5)$ which lead to different nonuniversal boundary conditions for the gaugino masses at the unification scale. We also consider the phenomenological implications of the nonuniversal gaugino masses arising from a grand unified theory in the context of large hadron collider. In particular we investigate the detection of heavy neutral Higgs bosons $H^0$, $A^0$from $H^0$, $A^0\to {\tilde{\chi }}_2^0{\tilde{\chi }}_2^0\to 4l$ and study the possibilities of detecting the neutral Higgs bosons in cascade decays, including the decays ${\tilde{\chi }}_2^0\to h^0(H^0,A^0){\tilde{\chi }}_1^0\to b\overline{b}{\tilde{\chi }}_1^0$.

The reduced matrix elements $a_2$ and $d_2$ are computed in lattice QCD with $N_f=2$ flavors of light dynamical (sea) quarks. For proton and neutron targets we obtain as our best estimates $d_2^{(p)}=0.004(5)$ and $d_2^{(n)}=-0.001(3)$, respectively, in the $\overline{\mathrm{MS}}$ scheme at $Q^2=5{\mathrm{GeV}}^2$, while for $a_2$ we find $a_2^{(p)}=0.077(12)$ and $a_2^{(n)}=-0.005(5)$, where the errors are purely statistical.

We study the productions of $p$-wave mesons $K_0^{*}(1430)$, $K_1(1270)$, and $K_1(1400)$ in $B$ decays. By the generalized factorization approach, we find that the branching ratios of $B\to K_0^{*}(1430)\varphi$ are similar to those of $B\to K\varphi$ while the branching ratios of $B\to K_1(1270)\varphi$ and $B\to K_1(1400)\varphi$ are $O({10}^{-5})$ and $O({10}^{-6})$, respectively. In terms of the observation of $B\to K_1(1270)\gamma$ by BELLE, we can remove the sign ambiguity in the mixing angle for physical states $K_1(1270)$ and $K_1(1400)$. In addition, we analyze annihilation contributions in the decays $B\to K_1\varphi$ and we conclude that they could be neglected.

Within an explicit scalar QED model we compare, at fixed $x\ll 1$, the leading-twist $K_{\perp }$-dependent “quark” distribution $f_{\mathrm{q}}(x,K_{\perp })$ probed in deep inelastic scattering and Drell-Yan production and show that the model is consistent with the universality of $f_{\mathrm{q}}(x,K_{\perp })$. The extension of the model from the aligned jet to the symmetric kinematical regime reveals interesting properties of the physics of Coulomb rescatterings when comparing DIS and DY processes. At small $x$ the transverse momentum $⟨k_{\perp }^2⟩$ induced by multiple scattering on a single center is process dependent, as well as the transverse momentum broadening occurring in collisions on a finite size nuclear target.

The quartic Higgs self-coupling is the final measurement in the Higgs potential needed to fully understand electroweak symmetry breaking. None of the present or future colliders are known to be able to determine this parameter. We study the chances of measuring the quartic self-coupling at hadron colliders in general and at the very large hadron collider in particular. We find the prospects challenging.

Upward-going stopping muons initiated by atmospheric ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$ interactions in the rock below the Soudan 2 detector have been isolated, together with a companion sample of neutrino-induced single muons, created within the detector, which travel downwards and exit. The downward-going sample is consistent with the atmospheric-neutrino flux prediction, but the upward-going sample exhibits a sizable depletion. Both are consistent with previously reported Soudan 2 neutrino-oscillation results. Inclusion of the two samples in an all-event likelihood analysis, using recent 3D-atmospheric-neutrino-flux calculations, reduces both the allowed oscillation parameter region and the probability of the no-oscillation hypothesis.

We present a measurement of the time-dependent $CP$-violating asymmetry in $B^0\to K^{*0}\gamma$ decays with $K^{*0}\to K_S^0{\pi }^0$ based on $232\times {10}^6$ ${\rm Y}(4S)\to B\overline{B}$ decays collected with the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider at SLAC. In a sample containing $157\pm 16$ signal decays, we measure $S_{K^{*0}\gamma }=-0.21\pm 0.40\pm 0.05$ and $C_{K^{*0}\gamma }=-0.40\pm 0.23\pm 0.03$, where the first error is statistical and the second systematic. We also explore $B^0\to K_S^0{\pi }^0\gamma$ decays with $1.1<m_{K_S^0{\pi }^0}<1.8$ $\mathrm{GeV}/c^2$ and find $59\pm 13$ signal events with $S_{K_S^0{\pi }^0\gamma }=0.9\pm 1.0\pm 0.2$ and $C_{K_S^0{\pi }^0\gamma }=-1.0\pm 0.5\pm 0.2$.

We consider the first law of black hole thermodynamics in an asymptotically anti-de Sitter spacetime in the class of gravitational theories whose gravitational Lagrangian is an arbitrary function of the Ricci scalar. We first show that the conserved quantities in this class of gravitational theories constructed through conformal completion remain unchanged under the conformal transformation into the Einstein frame. We then prove that the mass and the angular momenta defined by these conserved quantities, along with the entropy defined by the Noether charge, satisfy the first law of black hole thermodynamics, not only in Einstein gravity but also in the higher curvature gravity within the class under consideration. We also point out that it is naturally understood in the symplectic formalism that the mass satisfying the first law should be necessarily defined associated with the timelike Killing vector nonrotating at infinity. Finally, a possible generalization into a wider class of gravitational theories is discussed.

We present a measurement of the top pair production cross section in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$. We collect a data sample with an integrated luminosity of $194\pm 11{\mathrm{pb}}^{-1}$ with the CDF II detector at the Fermilab Tevatron. We use an artificial neural network technique to discriminate between top pair production and background processes in a sample of 519 lepton+jets events, which have one isolated energetic charged lepton, large missing transverse energy and at least three energetic jets. We measure the top pair production cross section to be ${\sigma }_{t\overline{t}}=6.6\pm 1.1\pm 1.5\mathrm{pb}$, where the first uncertainty is statistical and the second is systematic.