In this paper, we discuss the observation of exclusive events using the dijet mass fraction as measured by the CDF Collaboration at the Fermilab Tevatron. We compare the data to Pomeron exchange inspired models as well as soft color interaction ones. We also provide the prediction on the dijet mass fraction at the CERN LHC using both exclusive and inclusive diffractive events.

A charged Higgs pair can be produced at an $ee$ collider through a $t$-channel exchange of a heavy neutrino ($N$) via $e^{+}{e}^{-}\to H^{+}{H}^{-}$ and, if $N$ is a Majorana particle, also via the lepton number violating (LNV) like-sign reaction $e^{\pm }{e}^{\pm }\to H^{\pm }{H}^{\pm }$. Assuming no a priori relation between the effective $eN{H}^{+}$ coupling ($\xi$) and light neutrino masses, we show that this interaction vertex can give a striking enhancement to these charged Higgs pair production processes. In particular, the LNV $H^{-}{H}^{-}$ signal can probe $N$ at the International Linear Collider (ILC) in the mass range $100\mathrm{GeV}\lesssim m_N\lesssim {10}^4\mathrm{TeV}$ and with the effective mixing angle $\xi$ in the range ${10}^{-4}\lesssim {\xi }^2\lesssim {10}^{-8}$—well within its perturbative unitarity bound and the $\beta {\beta }_{0\nu }$ limit. The lepton number conserving $e^{+}{e}^{-}\to H^{+}{H}^{-}$ mode can be sensitive to, e.g., an $\mathcal{O}(10)\mathrm{TeV}$ heavy Majorana neutrino at a 500 GeV ILC, if ${\xi }^2\gtrsim 0.001$.

We calculate the signal-to-noise ratio (SNR) of the stochastic gravitational-wave background in an extreme case that its spectrum has a sharp falloff with its amplitude close to the detection threshold. Such a spectral feature is a characteristic imprint of the change in the number of relativistic degrees of freedom on the stochastic background generated during inflation in the early Universe. We find that, although SNR is maximal with the correct template which is proportional to the assumed real spectrum, its sensitivity to the shape of template is fairly weak indicating that a simple power-law template is sufficient to detect the signature.

We perform the first three-dimensional measurement of the amplitudes of $B\to \psi (2S)K^{*}$ and $B\to {\chi }_{c1}{K}^{*}$ decays and update our previous measurement for $B\to J/\psi K^{*}$. We use a data sample collected with the BABAR detector at the PEP-II storage ring, corresponding to $232\times {10}^6$ $B\overline{B}$ pairs. The longitudinal polarization of decays involving a $J^{PC}=1^{++}$ ${\chi }_{c1}$ meson is found to be larger than that with a $1^{--}$ $J/\psi$ or $\psi (2S)$ meson. No direct $CP$-violating charge asymmetry is observed.

The Casimir effect giving rise to an attractive or repulsive force between the configuration boundaries that confine the massless scalar field is reexamined for one- to three-dimensional pistons in this paper. Especially, we consider Casimir pistons with hybrid boundary conditions, where the boundary condition on the piston is Neumann and those on other surfaces are Dirichlet. We show that the Casimir force on the piston is always repulsive, in contrast with the same problem where the boundary conditions are Dirichlet on all surfaces.

We study the global geometry of a general class of spacetimes of relevance to the supersymmetric three-dimensional anti–de Sitter space/two-dimensional conformal field theory (${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$) correspondence in 11-dimensional supergravity. Specifically, we study spacetimes admitting a globally defined ${\mathbb{R}}^{1,1}$ frame, a globally defined frame bundle with structure group contained in $\mathrm{Spin}(7)$, and an ${\mathrm{AdS}}_3$ event horizon or conformal boundary. We show how the global frame bundle may be canonically realized by globally defined null sections of the spin bundle, which we use to truncate 11-dimensional supergravity to a gravitational theory of a frame with structure group $\mathrm{Spin}(7)$, $SU(4)$, or $Sp(2)$. By imposing an ${\mathrm{AdS}}_3$ boundary condition on the truncated supergravity equations, we define the geometry of all ${\mathrm{AdS}}_3$ horizons or boundaries which can be obtained from solutions of these truncations. In the most generic case we study, we reproduce the most general conditions for an ${\mathrm{AdS}}_3$ manifold in M-theory to admit a Killing spinor. As a consistency check on our definitions of AdS geometries we verify that they are satisfied by known gauged supergravity ${\mathrm{AdS}}_3$ solutions. We discuss future applications of our results.

We show that the maximally supersymmetric vacua of minimal $d=5$ $N=1$ sugra remain maximally supersymmetric solutions when taking into account higher order corrections.

Thermalization of quark-gluon plasmas in heavy-ion collisions is a difficult theoretical problem. One theoretical goal has been to understand the physics of thermalization in the relatively simplifying limit of arbitrarily high energy collisions, where the running coupling ${\alpha }_{\mathrm{s}}$ is weak. One of the current roadblocks to achieving this goal is lack of knowledge about the behavior of plasma instabilities when particle distributions are highly anisotropic. In particular, it has not been known how the magnetic fields generated by plasma instabilities scale with anisotropy. In this paper, we use numerical simulations in a first attempt to determine this scaling.

The combined action of gravity and quantum mechanics gives rise to a minimum time uncertainty in the lowest order approximation of a perturbative scheme, in which quantum effects are regarded as corrections to the classical spacetime geometry. From the nonperturbative point of view, both gravity and quantum mechanics are treated on equal footing in a description that already contains all possible backreaction effects as those above in a nonlinear manner. In this paper, the existence or not of such minimum time uncertainty is analyzed in the context of Schwarzschild–anti-de Sitter black holes using the isolated horizon formalism. We show that from a perturbative point of view, a nonzero time uncertainty is generically present owing to the energy scale introduced by the cosmological constant, while in a quantization scheme that includes nonperturbatively the effects of that scale, an arbitrarily high time resolution can be reached.

We present a robust strategy to veto certain classes of instrumental glitches that appear at the output of interferometric gravitational-wave detectors. This veto method is “physical” in the sense that, in order to veto a burst trigger, we make use of our knowledge of the coupling of different detector subsystems to the main detector output. The main idea behind this method is that the noise in an instrumental channel $X$ can be transferred to the detector output (channel $H$) using the transfer function from $X$ to $H$, provided the noise coupling is linear and the transfer function is unique. If a nonstationarity in channel $H$ is causally related to one in channel $X$, the two have to be consistent with the transfer function. We formulate two methods for testing the consistency between the burst triggers in channel $X$ and channel $H$. One method makes use of the null stream constructed from channel $H$ and the transferred channel $X$, and the second involves cross correlating the two. We demonstrate the efficiency of the veto by “injecting” instrumental glitches in the hardware of the GEO 600 detector. The veto safety is demonstrated by performing gravitational-wave–like hardware injections. We also show an example application of this method using 5 days of data from the fifth science run of GEO 600. The method is found to have very high veto efficiency with a very low accidental veto rate.

As current and future experiments probe strong gravitational regimes around neutron stars and black holes, it is desirable to have theoretically sound alternatives to general relativity against which to test observations. Here we study the consequences of one such generalization, Einstein-aether theory, for the properties of nonrotating neutron stars. This theory has a parameter range that satisfies all current weak-field tests. We find that within this range it leads to lower maximum neutron star masses, as well as larger surface redshifts at a particular mass, for a given nuclear equation of state. For nonrotating black holes and neutron stars, the innermost stable circular orbit is only slightly modified in this theory.

The left-handed sneutrino in the minimal supersymmetric standard model (MSSM) has been ruled out as a viable thermal dark matter candidate, due to conflicting constraints from direct detection experiments and from the measurement of the dark matter relic density. The intrinsic fine-tuning problem of the MSSM, however, motivates an extension with a new $U(1{)}^{\prime }$ gauge symmetry. We show that in the $U(1{)}^{\prime }$-extended MSSM the right-handed sneutrino ${\tilde{\nu }}_R$ becomes a good thermal dark matter candidate. We identify two generic parameter space regions where the combined constraints from relic density determinations, direct detection, and collider searches are all satisfied.

In this paper we show how some flavor symmetries may be derived from the heterotic string, when compactified on a 6D orbifold. In the body of the paper we focus on the $D_4$ family symmetry, recently obtained in $Z_3\times Z_2$ orbifold constructions. We show how this flavor symmetry constrains fermion masses, as well as the soft SUSY breaking mass terms. Flavor symmetry breaking can generate the hierarchy of fermion masses and at the same time the flavor symmetry suppresses large flavor changing neutral current processes.

IceCube, a cubic kilometer neutrino telescope, will be capable of probing neutrino-nucleon interactions in the ultrahigh energy regime, far beyond the energies reached by colliders. In this article we introduce a new observable that combines several advantages; it only makes use of the upward-going neutrino flux, so that the Earth filters the atmospheric muons, and it is only weakly dependent on the initial astrophysical flux uncertainties.

The potential to discover a standard model-like Higgs boson at the LHC in the mass range from 150–180 GeV, decaying into a pair of W bosons with subsequent leptonic decays, has been established during the last 10 years. Assuming that such a signal will eventually be observed, the analysis described in this paper investigates how accurate the signal cross section can be measured and how the observable lepton $p_{\mathrm{T}}$ spectra can be used to constrain the mass of the Higgs boson. Combining the signal cross section with the analysis of the lepton $p_{\mathrm{T}}$ spectra and assuming the SM Higgs cross section is known with an accuracy of $\pm 5\%$, our study indicates that an integrated luminosity of about $10{\mathrm{fb}}^{-1}$ allows to measure the mass of a SM Higgs boson with an accuracy between 2 and 2.5 GeV.

We study the decays $B^0\to J/\psi {\pi }^{+}{\pi }^{-}$ and $B^{+}\to J/\psi {\pi }^{+}{\pi }^0$, including intermediate resonances, using a sample of $382\times {10}^6$ $B\overline{B}$ pairs recorded by the BABAR detector at the PEP-II $e^{+}{e}^{-}$ $B$ factory. We measure the branching fractions $\mathcal{B}(B^0\to J/\psi {\rho }^0)=(2.7\pm 0.3\pm 0.2)\times {10}^{-5}$ and $\mathcal{B}(B^{+}\to J/\psi {\rho }^{+})=(5.0\pm 0.7\pm 0.3)\times {10}^{-5}$. We also set the following upper limits at the 90% confidence level: $\mathcal{B}(B^0\to J/\psi {\pi }^{+}{\pi }^{-}\mathrm{\text{nonresonant}})<1.2\times {10}^{-5}$, $\mathcal{B}(B^0\to J/\psi f_2)<4.6\times {10}^{-6}$, and $\mathcal{B}(B^{+}\to J/\psi {\pi }^{+}{\pi }^0\mathrm{\text{nonresonant}})<7.3\times {10}^{-6}$. We measure the charge asymmetry in charged $B$ decays to $J/\psi \rho$ to be $-0.11\pm 0.12\pm 0.08$.

We consider  $\mathcal{N}=(1,1)$ super Yang-Mills theory in $1+1$ dimensions with fundamentals at large $N_c$. A Chern-Simons term is included to give mass to the adjoint partons. Using the spectrum of the theory, we calculate thermodynamic properties of the system as a function of the temperature and the Yang-Mills coupling. In the large-$N_c$ limit there are two noncommunicating sectors, the glueball sector, which we presented previously, and the mesonlike sector that we present here.  We find that the mesonlike sector dominates the thermodynamics. Like the glueball sector, the meson sector has a Hagedorn temperature $T_H$, and we show that the Hagedorn temperature grows with the coupling. We calculate the temperature and coupling dependence of the free energy for temperatures below $T_H$. As expected, the free energy for weak coupling and low temperature grows quadratically with the temperature. Also the ratio of the free energies at strong coupling compared to weak coupling, $r_{s-w}$, for low temperatures grows quadratically with $T$. In addition, our data suggest that $r_{s-w}$ tends to zero in the continuum limit at low temperatures.

A version of the virial theorem, which takes into account the effects of the noncompact extra dimensions, is derived in the framework of the brane world models. In the brane world scenario, the four-dimensional effective Einstein equation has some extra terms, called dark radiation and dark pressure, respectively, which arise from the embedding of the 3-brane in the bulk. To derive the generalized virial theorem, we use a method based on the collisionless Boltzmann equation. The dark radiation term generates an equivalent mass term (the dark mass), which gives an effective contribution to the gravitational energy. This term may account for the well-known virial theorem mass discrepancy in actual clusters of galaxies. An approximate solution of the vacuum field equations on the brane, corresponding to weak gravitational fields, is also obtained, and the expressions for the dark radiation and dark mass are derived. The qualitative behavior of the dark mass is similar to that of the observed virial mass in clusters of galaxies. We compare our model with the observational data for galaxy clusters, and we express all the physical parameters of the model in terms of observable quantities. In particular, we predict that the dark mass must extend far beyond the presently considered virial radius. The behavior of the galaxy cluster velocity dispersion in brane world models is also considered. Therefore the study of the matter distribution and velocity dispersion at the extragalactic scales could provide an efficient method for testing the multidimensional physical models.

We show that the vorticity appearing in stationary vacuum spacetimes is always related to the existence of a flow of superenergy on the plane orthogonal to the vorticity vector. This result, together with the previously established link between vorticity and superenergy in radiative (Bondi-Sachs) spacetimes, strengthens further the case for this latter quantity as the cause of frame dragging.

We construct a conserved, symmetric energy-momentum (pseudo-)tensor for Chern-Simons modified gravity, thus demonstrating that the theory is Lorentz invariant. The tensor is discussed in relation to other gravitational energy-momentum tensors and analyzed for the Schwarzschild, Reissner-Nordstrom, and Friedmann-Robertson-Walker solutions. To our knowledge this is the first confirmation that the Reissner-Nordstrom and Friedmann-Robertson-Walker metrics are solutions of the modified theory.