This paper reports a search for nonstandard model topquark resonances, $Z^{\prime }$, decaying to $t\overline{t}\to W^{+}b{W}^{-}\overline{b}$, where both $W$ decay to quarks. We examine the top-antitop quark invariant mass spectrum for the presence of narrow resonant states. The search uses a data sample of $p\overline{p}$ collisions at a center of mass energy of 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron, with an integrated luminosity of $2.8{\mathrm{fb}}^{-1}$. No evidence for top-antitop quark resonant production is found. We place upper limits on the production cross section times branching ratio for a specific topcolor assisted technicolor model in which the $Z^{\prime }$ has a width of ${\Gamma }_{Z^{\prime }}=0.012M_{Z^{\prime }}$. Within this model, we exclude a $Z^{\prime }$ boson with masses below $805\mathrm{GeV}/c^2$ at the 95% confidence level.

We present a search for the pair production of first generation scalar leptoquarks ($LQ$) in data corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$ collected with the D0 detector at the Fermilab Tevatron Collider in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$. In the channel $LQLQ\to eq{\nu }_e{q}^{\prime }$, where $q$, $q^{\prime }$ are $u$ or $d$ quarks, no significant excess of data over background is observed, and we set a 95% C.L. lower limit of 326 GeV on the $LQ$ mass, assuming equal probabilities of $LQ$ decays to $eq$ and ${\nu }_e{q}^{\prime }$.

We report constraints on antineutrino oscillation parameters that were obtained by using the two MINOS detectors to measure the 7% muon antineutrino component of the NuMI neutrino beam. In the Far Detector, we select 130 events in the charged-current muon antineutrino sample, compared to a prediction of $136.4\pm 11.7(\mathrm{stat}{)}_{-8.9}^{+10.2}(\mathrm{syst})$ events under the assumption $|\Delta {\overline{m}}^2|=2.32\times {10}^{-3}{\mathrm{eV}}^2$, ${sin}^2(2\overline{\theta })=1.0$. Assuming no oscillations occur at the Near Detector baseline, a fit to the two-flavor oscillation approximation constrains $|\Delta {\overline{m}}^2|<3.37\times {10}^{-3}{\mathrm{eV}}^2$ at the 90% confidence level with ${sin}^2(2\overline{\theta })=1.0$.

We report the observation of the baryonic $B$ decay ${\overline{B}}^0\to {\Lambda }_c^{+}\overline{\Lambda }{K}^{-}$ with a significance larger than 7 standard deviations based on $471\times {10}^6$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II storage ring at SLAC. We measure the branching fraction for the decay ${\overline{B}}^0\to {\Lambda }_c^{+}\overline{\Lambda }{K}^{-}$ to be $(3.8\pm {0.8}_{\mathrm{stat}}\pm {0.2}_{\mathrm{sys}}\pm {1.0}_{{\Lambda }_c^{+}})\times {10}^{-5}$. The uncertainties are statistical, systematic, and due to the uncertainty in the ${\Lambda }_c^{+}$ branching fraction. We find that the ${\Lambda }_c^{+}{K}^{-}$ invariant-mass distribution shows an enhancement above $3.5\mathrm{GeV}/c^2$.

We propose a new model of intermediate inflation in the framework of brane cosmology in the presence of tachyonic field. We derive the expressions for the model parameters and estimate the observable parameters in the model numerically. We finally conclude that these parameters fit well with the observational data.

The calculation of quadratic divergences in Einstein-Maxwell theory with a possible cosmological constant is considered. We describe a method of calculation, using the background-field method, that is sensitive to quadratic divergences, is respectful of gauge invariance, and is independent of gauge conditions. A standard renormalization group analysis is applied to the result where it is shown that the quadratic divergences do lead to asymptotic freedom as found in the original paper of Robinson and Wilczek. The role and nature of these quadratic divergences is critically evaluated in light of recent criticism. Within the context of the background-field method, it is shown that it is possible to define the charge in a physically motivated way in which the quadratic divergences do not play a role. This latter view is studied in more depth in a toy model described in an appendix.

One of the main signatures of primordial non-Gaussianity of the local type is a scale-dependent correction to the bias of large-scale structure tracers such as galaxies or clusters, whose amplitude depends on the bias of the tracers itself. The dominant source of noise in the power spectrum of the tracers is caused by sampling variance on large scales (where the non-Gaussian signal is strongest) and shot noise arising from their discrete nature. Recent work has argued that one can avoid sampling variance by comparing multiple tracers of different bias, and suppress shot noise by optimally weighting halos of different mass. Here we combine these ideas and investigate how well the signatures of non-Gaussian fluctuations in the primordial potential can be extracted from the two-point correlations of halos and dark matter. On the basis of large $N$-body simulations with local non-Gaussian initial conditions and their halo catalogs we perform a Fisher matrix analysis of the two-point statistics. Compared to the standard analysis, optimal weighting and multiple-tracer techniques applied to halos can yield up to 1 order of magnitude improvements in $f_{\mathrm{NL}}$-constraints, even if the underlying dark matter density field is not known. In this case one needs to resolve all halos down to ${10}^{10}{h}^{-1}{\mathrm{M}}_{\odot }$ at $z=0$, while with the dark matter this is already achieved at a mass threshold of ${10}^{12}{h}^{-1}{\mathrm{M}}_{\odot }$. We compare our numerical results to the halo model and find satisfactory agreement. Forecasting the optimal $f_{\mathrm{NL}}$-constraints that can be achieved with our methods when applied to existing and future survey data, we find that a survey of $50h^{-3}{\mathrm{Gpc}}^3$ volume resolving all halos down to ${10}^{11}{h}^{-1}{\mathrm{M}}_{\odot }$ at $z=1$ will be able to obtain ${\sigma }_{f_{\mathrm{NL}}}\sim 1$ (68% cl), a factor of $\sim 20$ improvement over the current limits. Decreasing the minimum mass of resolved halos, increasing the survey volume or obtaining the dark matter maps can further improve these limits, potentially reaching the level of ${\sigma }_{f_{\mathrm{NL}}}\sim 0.1$. This precision opens up the possibility to distinguish different types of primordial non-Gaussianity and to probe inflationary physics of the very early Universe.

We present a holographic model of the Dvali-Gabadadze-Porrati scenario with a Gauss-Bonnet term in the bulk. We concentrate on the solution that generalizes the normal Dvali-Gabadadze-Porrati branch. It is well known that this branch cannot describe the late-time acceleration of the universe even with the inclusion of a Gauss-Bonnet term. Here, we show that this branch in the presence of a Gauss-Bonnet curvature effect and a holographic dark energy with the Hubble scale as the infrared cutoff can describe the late-time acceleration of the universe. It is worthwhile to stress that such an energy density component cannot do the same job on the normal Dvali-Gabadadze-Porrati branch (without Gauss-Bonnet modifications) nor in a standard four-dimensional relativistic model. The acceleration on the brane is also presented as being induced through an effective dark energy which corresponds to a balance between the holographic one and geometrical effects encoded through the Hubble parameter.

In a Universe with a detectable nontrivial spatial topology, the last scattering surface contains pairs of matching circles with the same distribution of temperature fluctuations—the so-called circles-in-the-sky. Searches undertaken for nearly antipodal pairs of such circles in cosmic microwave background maps have so far been unsuccessful. Previously, we had shown that the negative outcome of such searches, if confirmed, should in principle be sufficient to exclude a detectable nontrivial spatial topology for most observers in very nearly flat ($0<\mid {\Omega }_{\mathrm{tot}}-1\mid \lesssim {10}^{-5}$) (curved) universes. More recently, however, we have shown that this picture is fundamentally changed if the universe turns out to be exactly flat. In this case, there are many potential pairs of circles with large deviations from antipodicity that have not yet been probed by existing searches. Here, we study under what conditions the detection of a single pair of circles-in-the-sky can be used to uniquely specify the topology and the geometry of the spatial section of the Universe. We show that from the detection of a single pair of matching circles one can infer whether the spatial geometry is flat or not, and if so we show how to determine the topology (apart from one case) of the Universe using this information. An important additional outcome of our results is that the dimensionality of the circles-in-the-sky parameter space that needs to be spanned in searches for matching pairs of circles is reduced from six to 5 degrees of freedom, with a significant reduction in the necessary computational time.

The generalized Swiss-cheese model, consisting of a Lemaître-Tolman (inhomogeneous dust) region matched, by way of a comoving boundary surface, onto a Robertson-Walker background of homogeneous dust, has become a standard construction in modern cosmology. Here, we ask if this construction can be made more realistic by introducing some evolution of the boundary surface. The answer we find is no. To maintain a boundary surface using the Darmois-Israel junction conditions, as opposed to the introduction of a surface layer, the boundary must remain exactly comoving. The options are to drop the assumption of dust or allow the development of surface layers. Either option fundamentally changes the original construction.

We give the lens equation for light deflections caused by point mass condensations in an otherwise spatially homogeneous and flat universe. We assume the signal from a distant source is deflected by a single condensation before it reaches the observer. We call this deflector an embedded lens because the deflecting mass is part of the mean density. The embedded lens equation differs from the conventional lens equation because the deflector mass is not simply an addition to the cosmic mean. We prescribe an iteration scheme to solve this new lens equation and use it to compare our results with standard linear lensing theory. We also compute analytic expressions for the lowest order corrections to image amplifications and distortions caused by incorporating the lensing mass into the mean. We use these results to estimate the effect of embedding on strong lensing magnifications and ellipticities and find only small effects, $<1\%$, contrary to what we have found for time delays and for weak lensing, $\sim 5\%$.

We present a method for detection of weak continuous signals from sources in binary systems via the incoherent combination of many short coherently analyzed segments. The main focus of the work is on the construction of a metric on the parameter space for such signals for use in matched-filter based searches. The metric is defined using a maximum likelihood detection statistic applied to a binary orbit phase model including eccentricity. We find that this metric can be accurately approximated by its diagonal form in the regime where the segment length is $\ll$ the orbital period. Hence, correlations between parameters are effectively removed by the combination of many independent observations. We find that the ability to distinguish signal parameters is independent of the total semicoherent observation span (for the semicoherent span $\gg$ the segment length) for all but the orbital angular frequency. Increased template density for this parameter scales linearly with the observation span. We also present two example search schemes. The first use a reparametrized phase model upon which we compute the metric on individual short coherently analyzed segments. The second assumes long $\gg$ the orbital period segment lengths from which we again compute the coherent metric and find it to be approximately diagonal. In this latter case we also show that the semicoherent metric is equal to the coherent metric.

Based on the infrared improved soft-wall AdS/QCD model which can lead to a consistent prediction for the mass spectra of light resonance mesons, we extend it to the finite temperature system and carry out the calculation for the quark number susceptibility with finite quark mass. As a consequence, we show that the quark number susceptibility grows rapidly with a continuous blowup in a narrow temperature interval as the temperature increases, and there is a peak when the temperature is around $T\simeq 160\sim 190\mathrm{MeV}$ depending slightly on the models. The resulting critical temperature is about 170 MeV, which agrees remarkably with the lattice QCD calculation.

The extension of the standard model by a spontaneously broken abelian gauge group based on the $L_{\mu }-L_{\tau }$ lepton number can resolve the long-standing discrepancy between experimental and theoretical values for the magnetic moment of the muon. It furthermore naturally generates $\mu \mathrm{\text{−}}\tau$ symmetric lepton mixing, introduces neutrino nonstandard interactions, and the associated gauge boson $Z^{\prime }$ serves as a mediator to the right-handed neutrino sector. A detailed fit to electroweak data is performed to identify the allowed values for the mass of $Z^{\prime }$ and its mixing with the standard model $Z$. An economical new scalar sector is constructed that spontaneously breaks $L_{\mu }-L_{\tau }$ and leads to experimental consequences such as lepton flavor violation and collider signatures. Furthermore we discuss the nonabelian extension to an $SU(2{)}^{\prime }$, particularly the neutrino sector.

A quasiparticle model has been employed to describe the ($2+1$)-flavor lattice QCD equation of state with physical quark masses. The interaction part of the equation of state has been mapped to the effective fugacities of otherwise noninteracting quasigluons and quasiquarks. The mapping is found to be exact for the equation of state. The model leads to nontrivial dispersion relations for quasipartons. The dispersion relations, effective quasiparticle number densities, and trace anomaly have been investigated employing the model. A virial expansion for the equation of state has further been obtained to investigate the role of interactions in quark-gluon plasma. Finally, Debye screening in quark-gluon plasma has been studied employing the model.

The partial decay widths of lowest lying negative parity baryons belonging to the $\mathbf{70}$-plet of $SU(6)$ are analyzed in the framework of the $1/N_c$ expansion. The channels considered are those with single pseudoscalar meson emission. The analysis is carried out to sub-leading order in $1/N_c$ and to first order in $SU(3)$ symmetry breaking. Conclusions about the magnitude of $SU(3)$ breaking effects along with predictions for some unknown or poorly determined partial decay widths of known resonances are obtained.

The meson-photon transition form factors $\gamma {\gamma }^{*}\to P$ ($P$ stands for $\pi$, $\eta$ and ${\eta }^{\prime }$) provide strong constraints on the distribution amplitudes of the pseudoscalar mesons. In this paper, these transition form factors are calculated under the light-cone perturbative QCD approach, in which both the valence and nonvalence quarks’ contributions have been taken into consideration. To be consistent, a unified wave function model is adopted to analyze these form factors. It is shown that with the proper charm component $f_{{\eta }^{\prime }}^c\sim -30\mathrm{MeV}$ and a moderate DA with $B\sim 0.30$, the experimental data on $Q^2{F}_{\eta \gamma }(Q^2)$ and $Q^2{F}_{{\eta }^{\prime }\gamma }(Q^2)$ in the whole $Q^2$ region can be explained simultaneously. Furthermore, a detailed discussion on the form factors’ uncertainties caused by the constituent quark masses $m_q$ and $m_s$, the parameter $B$, the mixing angle $\varphi$, and $f_{{\eta }^{\prime }}^c$ are presented. It is found that, by adjusting these parameters within their reasonable regions, one can improve the form factor to a certain degree but cannot solve the puzzle for $Q^2{F}_{\pi \gamma }(Q^2)$, especially to explain the behavior of the $\pi -\gamma$ form factor within the whole $Q^2$ region consistently. We hope further experimental data on these form factors in the large $Q^2$ region can clarify the present situation.

We explore the discovery prospects for $B^{\prime }{\overline{B}}^{\prime }$ pair production followed by direct decays $B^{\prime }\to bX$, where $B^{\prime }$ is a new quark and $X$ is a long-lived neutral particle. We develop optimized cuts in the $(m_{B^{\prime }},m_X)$ plane and show that the 7 TeV LHC with an integrated luminosity of $1(10){\mathrm{fb}}^{-1}$ may exclude masses up to $m_{B^{\prime }}\sim 620(800)\mathrm{GeV}$, completely covering the mass range allowed for new quarks that get mass from electroweak symmetry breaking. This analysis is applicable to other models with $b\overline{b}{\mathrm{E̸}}_T$ signals, including supersymmetric models with bottom squarks decaying directly to neutralinos, and models with exotic quarks decaying directly to GeV-scale dark matter. To accommodate these and other interpretations, we also present model-independent results for the $b\overline{b}{\mathrm{E̸}}_T$ cross section required for exclusion and discovery.

We use ($111\pm 1$) million ${\rm Y}(3S)$ and ($89\pm 1$) million ${\rm Y}(2S)$ events recorded by the BABAR detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to $e^{+}{e}^{-}$ pairs by the detector material. We observe ${\rm Y}(3S)\to \gamma {\chi }_{b0,2}(1P)$ decay, make precise measurements of the branching fractions for ${\chi }_{b1,2}(1P,2P)\to \gamma {\rm Y}(1S)$ and ${\chi }_{b1,2}(2P)\to \gamma {\rm Y}(2S)$ decays, and search for radiative decay to the ${\eta }_b(1S)$ and ${\eta }_b(2S)$ states.

We study $B^{-}$ meson decays to $\overline{p}\Lambda D^{(*)0}$ final states using a sample of $657\times {10}^{6}B\overline{B}$ events collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The observed branching fraction for $B^{-}\to \overline{p}\Lambda D^0$ is $({1.43}_{-0.25}^{+0.28}\pm 0.18)\times {10}^{-5}$ with a significance of 8.1 standard deviations, where the uncertainties are statistical and systematic, respectively. Most of the signal events have the $\overline{p}\Lambda$ mass peaking near threshold. No significant signal is observed for $B^{-}\to \overline{p}\Lambda D^{*0}$ and the corresponding upper limit on the branching fraction is $4.8\times {10}^{-5}$ at the 90% confidence level.