We present “state-of-the-art” theoretical expressions for the triple differential $\overline{B}\to X_u{l}^{-}\overline{\nu }$ decay rate and for the $\overline{B}\to X_s\gamma$ photon spectrum, which incorporate all known contributions and smoothly interpolate between the “shape-function region” of large hadronic energy and small invariant mass, and the “OPE region” in which all hadronic kinematical variables scale with $M_B$. The differential rates are given in a form which has no explicit reference to the mass of the $b$ quark, avoiding the associated uncertainties. Dependence on $m_b$ enters indirectly through the properties of the leading shape function, which can be determined by fitting the $\overline{B}\to X_s\gamma$ photon spectrum. This eliminates the dominant theoretical uncertainties from predictions for $\overline{B}\to X_u{l}^{-}\overline{\nu }$ decay distributions, allowing for a precise determination of $|V_{ub}|$. In the shape-function region, short-distance and long-distance contributions are factorized at next-to-leading order in renormalization-group improved perturbation theory. Higher-order power corrections include effects from subleading shape functions where they are known. When integrated over sufficiently large portions in phase space, our results reduce to standard OPE expressions up to yet unknown $O({\alpha }_s^2)$ terms. Predictions are presented for partial $\overline{B}\to X_u{l}^{-}\overline{\nu }$ decay rates with various experimental cuts. An elaborate error analysis is performed that contains all significant theoretical uncertainties, including weak annihilation effects. We suggest that the latter can be eliminated by imposing a cut on high leptonic invariant mass.

In the framework of the extended $SU(2{)}_h\times SU(2{)}_l$ model we study the radiative decay of an extra gauge boson $Z^{\prime }$, $Z^{\prime }\to \gamma Z$. The data analysis results of the CDF collaboration at the Fermilab Tevatron allow one to establish not only the lower bound of the decay probability $Z^{\prime }\to \gamma Z$ normalized to Drell-Yan process $Z^{\prime }\to {\mu }^{+}{\mu }^{-}$, $R(Z^{\prime }\to \gamma Z/{\mu }^{+}{\mu }^{-})>1.4\times {10}^{-5}{cot}^2\varphi$, but also to estimate the mixing angle $\xi$ between the states $Z^{\prime }$ and $Z$, $|\xi |<5\times {10}^{-2}$, taking into account the additional mixing angle $\varphi$ related to the extended gauge group $SU(2{)}_h\times SU(2{)}_l$. The comparison with the decays $Z^{\prime }\to {\tau }^{+}{\tau }^{-}$ and $Z^{\prime }\to \overline{b}b$, $Z^{\prime }\to \overline{t}t$ based on the LEP data is also presented.

The effects of the Gribov copies on the gluon and ghost propagators are investigated in SU(2) Euclidean Yang-Mills theory quantized in the maximal Abelian gauge. The diagonal component of the gluon propagator displays the characteristic Gribov-type behavior. The off-diagonal component of the gluon propagator is found to be of the Yukawa type, with a dynamical mass originating from the dimension two condensate $⟨A_{\mu }^a{A}_{\mu }^a⟩$, which is also taken into account. Finally, the off-diagonal ghost propagator exhibits infrared enhancement.

Based on the Mathisson-Papapetrou-Dixon (MPD) equations and the Vaidya metric, the motion of a spinning point particle orbiting a nonrotating star while undergoing radiation-induced gravitational collapse is studied in detail. A comprehensive analysis of the orbital dynamics is performed assuming distinct central mass functions which satisfy the weak energy condition, in order to determine a correspondence between the choice of mass function and the spinning particle’s orbital response, as reflected in the gravitational waves emitted by the particle. The analysis presented here is likely most beneficial for the observation of rotating solar mass black holes or neutron stars in orbit around intermediate-sized Schwarzschild black holes undergoing radiation collapse. The possibility of detecting the effects of realistic mass accretion based on this approach is considered. While it seems unlikely to observe such effects based on present technology, they may perhaps become observable with the advent of future detectors.

We discuss and compare at length the results of two methods used recently to describe the thermodynamics of Taub-Newman-Unti-Tamburino (NUT) solutions in a de Sitter background. In the first approach ($\mathbb{C}$ approach), one deals with an analytically continued version of the metric while in the second approach ($\mathbb{R}$ approach), the discussion is carried out using the unmodified metric with Lorentzian signature. No analytic continuation is performed on the coordinates and/or the parameters that appear in the metric. We find that the results of both these approaches are completely equivalent modulo analytic continuation and we provide the exact prescription that relates the results in both methods. The extension of these results to the AdS/flat cases aims to give a physical interpretation of the thermodynamics of NUT-charged spacetimes in the Lorentzian sector. We also briefly discuss the higher-dimensional spaces and note that, analogous with the absence of hyperbolic NUTs in AdS backgrounds, there are no spherical Taub-NUT-dS solutions.

The metric ansatz (1) is used to describe the gravitational field of a beam pulse of spinning radiation (gyraton) in an arbitrary number of spacetime dimensions $D$. First we demonstrate that this metric belongs to the class of metrics for which all scalar invariants constructed from the curvature and its covariant derivatives vanish. Next, it is shown that the vacuum Einstein equations reduce to two linear problems in $(D-2)$-dimensional Euclidean space. The first is to find the static magnetic potential $\mathbf{A}$ created by a pointlike source. The second requires finding the electric potential $\Phi$ created by a pointlike source surrounded by given distribution of the electric charge. To obtain a generic gyraton-type solution of the vacuum Einstein equations it is sufficient to allow the coefficients in the corresponding harmonic decompositions of solutions of the linear problems to depend arbitrarily on retarded time $u$ and substitute the obtained expressions in the metric ansatz. These solutions are generalizations of the gyraton metrics found in [V. P. Frolov and D. V. Fursaev, Phys. Rev. D 71, 104034 (2005).]. We discuss properties of the solutions for relativistic gyratons and consider special examples.

We study the pulsar timing, focusing on the time delay induced by the gravitational field of the binary systems. In particular, we study the gravitomagnetic correction to the Shapiro time delay in terms of Keplerian and post-Keplerian parameters, and we introduce a new post-Keplerian parameter which is related to the intrinsic angular momentum of the stars. Furthermore, we evaluate the magnitude of these effects for the binary pulsar systems known so far. The expected magnitude is indeed small, but the effect is important per se.

We study here the gravitational collapse of a matter cloud with a nonvanishing tangential pressure in the presence of a nonzero cosmological term $\Lambda$. It is investigated how $\Lambda$ modifies the dynamics of the collapsing cloud and whether it affects the cosmic censorship. Conditions for bounce and singularity formation are derived. It is seen that when the tangential pressure vanishes, the bounce and singularity conditions reduce to the dust case studied earlier. The collapsing interior is matched to an exterior which is asymptotically de Sitter or anti–de Sitter, depending on the sign of the cosmological constant. The junction conditions for matching the cloud to the exterior are specified. The effect of $\Lambda$ on apparent horizons is studied in some detail and the nature of central singularity is analyzed. The visibility of singularity and implications for the cosmic censorship conjecture are discussed. It is shown that for a nonvanishing cosmological constant, both black hole and naked singularities do form as collapse end states in spacetimes which are asymptotically de Sitter or anti–de Sitter.

We show that one may pass from bulk to boundary thermodynamic quantities for rotating anti-de Sitter (AdS) black holes in arbitrary dimensions so that if the bulk quantities satisfy the first law of thermodynamics then so do the boundary conformal field theory (CFT) quantities. This corrects recent claims that boundary CFT quantities satisfying the first law may only be obtained using bulk quantities measured with respect to a certain frame rotating at infinity, and which therefore do not satisfy the first law. We show that the bulk black-hole thermodynamic variables, or equivalently therefore the boundary CFT variables, do not always satisfy a Cardy-Verlinde type formula, but they do always satisfy an AdS-Bekenstein bound. The universal validity of the Bekenstein bound is a consequence of the more fundamental cosmic-censorship bound, which we find to hold in all cases examined. We also find that at fixed entropy, the temperature of a rotating black hole is bounded above by that of a nonrotating black hole, in four and five dimensions, but not in six or more dimensions. We find evidence for universal upper bounds for the area of cosmological event horizons and black-hole horizons in rotating black-hole spacetimes with a positive cosmological constant.

New upper bounds on direct detection rates have been presented recently by a number of experimental collaborations working on searches for weakly interacting massive particles (WIMPs). In this paper we analyze how the constraints on relic neutralinos which can be derived from these results are affected by the uncertainties in the distribution function of WIMPs in the halo. Various different categories of velocity distribution functions are considered, and the ensuing implications for supersymmetric configurations derived. We conservatively conclude that current experimental data do not constrain neutralinos of small mass (below 50 GeV).

In the two-Higgs-doublet model (2HDM) with large extra dimensions (LED), we study the contributions of virtual Kaluza-Klein (KK) gravitons to 2HDM charged Higgs production, especially in the two important production processes $e^{+}{e}^{-}\to H^{+}{H}^{-}$ and $e^{+}{e}^{-}\to H^{-}t\overline{b}$, at future linear colliders (LC). We find that KK graviton effects can significantly modify these total cross sections and also their differential cross sections compared to their respective 2HDM values and, therefore, can be used to probe the effective scale ${\Lambda }_T$ up to several TeV. For example, at $\sqrt{s}=2\mathrm{TeV}$, the cross sections for $e^{+}{e}^{-}\to H^{+}{H}^{-}$ and $e^{+}{e}^{-}\to H^{-}t\overline{b}$ in the 2HDM are 7.4 fb for $m_{H^{-}}=150\mathrm{GeV}$ and 0.003 fb for $m_{H^{-}}=1.1\mathrm{TeV}$ and $\tan \beta =40$, while in LED they are 12.1 and 0.01 fb, respectively, for ${\Lambda }_T=4\mathrm{TeV}$.

The LENA (Low Energy Neutrino Astronomy) detector is proposed to be a large-volume liquid-scintillator device which will be highly suitable for the investigation of a variety of topics in astrophysics, geophysics and particle physics. In this paper, the potential of such a detector concerning the search for proton decay in the SUSY favored decay channel $p\to K^{+}\overline{\nu }$ is investigated. Based on Geant4, Monte Carlo simulations of the proton decay in the LENA detector as well as of the background radiation in the detection energy windows have been developed. From these simulations an efficiency of $65\%$ for the detection of a possible proton decay has been determined. Within ten years of measuring time a lower limit for the proton lifetime, concerning the decay channel investigated, of $\tau >4\times {10}^{34}\mathrm{y}$ could be reached.

I make a number of observations concerning discretization errors in twisted-mass lattice QCD that can be deduced by applying chiral perturbation theory including lattice artifacts. (1) The line along which the partially conserved axial current quark mass vanishes in the untwisted-mass–twisted-mass plane makes an angle to the twisted-mass axis which is a direct measure of $O(a)$ terms in the chiral Lagrangian, and is found numerically to be large; (2) Numerical results for pionic quantities in the mass plane show the qualitative properties predicted by chiral perturbation theory, in particular, an asymmetry in slopes between positive and negative untwisted quark masses; (3) By extending the description of the “Aoki regime” (where $m_q\sim a^2{\Lambda }_{\mathrm{QCD}}^3$) to next-to-leading order in chiral perturbation theory I show how the phase-transition lines and lines of maximal twist (using different definitions) extend into this region, and give predictions for the functional form of pionic quantities; (4) I argue that the recent claim that lattice artifacts at maximal twist have apparent infrared singularities in the chiral limit results from expanding about the incorrect vacuum state. Shifting to the correct vacuum (as can be done using chiral perturbation theory) the apparent singularities are summed into nonsingular, and furthermore predicted, forms. I further argue that there is no breakdown in the Symanzik expansion in powers of lattice spacing, and no barrier to simulating at maximal twist in the Aoki regime.

We perform $SU(3)$ lattice gauge theory simulations of the deconfinement transition attempting to mimic conditions encountered in heavy-ion collisions. Specifically, we perform a sudden temperature quench across the deconfinement temperature, and follow the response of the system in successive simulation sweeps under spatial lattice expansion and temperature falloff. In measurements of the Polyakov loop and structure functions a robust strong signal of global instability response is observed through the exponential growth of low momentum modes. Development of these long range modes isotropizes the system which reaches thermalization shortly afterwards, and enters a stage of quasiequilibrium expansion and cooling till its return to the confinement phase. The time scale characterizing full growth of the long range modes is largely unaffected by the conditions of spatial expansion and temperature variation in the system, and is much shorter than the scale set by the interval to return to the confinement phase. The wide separation of these two scales is such that it naturally results in isotropization times well inside 1 fm/c.

Study of the spectrum and structure of color nonsinglet combinations of quarks and antiquarks, neutralized by a nondynamical compensating color source, may provide an interesting way to address questions about QCD that cannot be addressed by experiment at the present time. These states can be simulated in lattice QCD and the results can be used to improve phenomenological models of hadrons. Here these ideas are applied to color triplet states of $qqqq$ and $qq\overline{q}$.

The possible discovery of the ${\Theta }^{+}$ pentaquark has motivated a number of studies of its nature using lattice QCD. While all the analyses thus far have focused on spin-$\frac{1}{2}$ states, here we report the results of the first exploratory study in quenched lattice QCD of pentaquarks with spin $\frac{3}{2}$. For the spin-$\frac{3}{2}$ interpolating field we use a product of the standard $N$ and $K^{*}$ operators. We do not find any evidence for the standard lattice resonance signature of attraction (i.e., binding at quark masses near the physical regime) in the $J^P={\frac{3}{2}}^{-}$ channel. Some evidence of binding is inferred in the isoscalar ${\frac{3}{2}}^{+}$ channel at several quark masses, in accord with the standard lattice resonance signature. This suggests that this is a good candidate for the further study of pentaquarks on the lattice.

Non-$D\overline{D}$ decay $\psi (3770)\to \rho \pi$ is searched for using a data sample of $(17.3\pm 0.5)\mathrm{p}{\mathrm{b}}^{-1}$ taken at the center-of-mass energy of 3.773 GeV by the BESII detector at the BEPC. No $\rho \pi$ signal is observed, and the upper limit of the cross section is measured to be $\sigma (e^{+}{e}^{-}\to \rho \pi )<6.0\mathrm{pb}$ at 90% C. L. Considering the interference between the continuum amplitude and the $\psi (3770)$ resonance amplitude, the branching fraction of $\psi (3770)$ decays to $\rho \pi$ is determined to be $\mathcal{B}(\psi (3770)\to \rho \pi )\in (6.0\times {10}^{-6},2.4\times {10}^{-3})$ at 90% C. L. This is in agreement with the prediction of the $S$- and $D$-wave mixing scheme of the charmonium states for solving the “$\rho \pi$ puzzle” between $J/\psi$ and $\psi (2S)$ decays.

We study a Hamiltonian realization of the phase space of $\kappa$-Poincaré algebra that yields a definition of velocity consistent with the deformed Lorentz symmetry. We are also able to determine the laws of transformation of spacetime coordinates and to define an invariant spacetime metric, discussing some possible experimental consequences.

Detection template families (DTFs) are built to capture the essential features of true gravitational waveforms using a small set of phenomenological waveform parameters. Buonanno, Chen, and Vallisneri [Phys. Rev. D 67, 104025 (2003)] proposed the BCV2 DTF to perform computationally efficient searches for signals from precessing binaries of compact stellar objects. Here we test the signal-matching performance of the BCV2 DTF for asymmetric-mass-ratio binaries, and specifically for double-black-hole binaries with component masses $(m_1,m_2)\in [6,12]M_{\odot }\times [1,3]M_{\odot }$, and for black-hole–neutron-star binaries with component masses $(m_1,m_2)=(10M_{\odot },1.4M_{\odot })$; we take all black holes to be maximally spinning. We find a satisfactory signal-matching performance, with fitting factors averaging between 0.94 and 0.98. We also scope out the region of BCV2 parameters needed for a template-based search, we evaluate the template match metric, we discuss a template-placement strategy, and we estimate the number of templates needed for searches at the LIGO design sensitivity. In addition, after gaining more insight in the dynamics of spin-orbit precession, we propose a modification of the BCV2 DTF that is parametrized by physical (rather than phenomenological) parameters. We test this modified “BCV2P” DTF for the ($10M_{\odot }$, $1.4M_{\odot }$) black-hole–neutron-star system, finding a signal-matching performance comparable to the BCV2 DTF, and a reliable parameter-estimation capability for target-binary quantities such as the chirp mass and the opening angle (the angle between the black-hole spin and the orbital angular momentum).