The reaction rates of the beta processes for all particles at arbitrary degeneracy are derived, and an analytic steady state equilibrium condition ${\mu }_n={\mu }_p+2{\mu }_e$ which results from the equality of electron and positron capture rates in the hot electron-positron plasma with nucleons is also found, if the matter is transparent to neutrinos. This simple analytic formula is valid only if electrons are nondegenerate or mildly degenerate, which is generally satisfied in the hot electron-positron plasma. Therefore, it can be used to efficiently determine the steady state of the hot matter with plenty of positrons. Based on this analytic condition, given the baryon number density and the temperature, if the nucleons are nondegenerate, only one algebraic equation for determining the electron fraction is obtained, which shows the great advantage of the analytic equilibrium condition.

The Belle Collaboration results on the observation of the $f_0(980)$ resonance in the reaction $\gamma \gamma \to {\pi }^{+}{\pi }^{-}$ are analyzed. It is argued that they point to the presence of mechanisms which give rise to a strong distortion of the $f_0(980)$ resonance shape in comparison with the shape of a solitary Breit-Wigner resonance. It is shown that the main factors responsible for the formation of the specific, steplike, shape of the $f_0(980)$ resonance in the $\gamma \gamma \to {\pi }^{+}{\pi }^{-}$ reaction cross section are the $K^{+}{K}^{-}$ loop mechanism of the $f_0(980)$ coupling to the $\gamma \gamma$ system and the destructive interference between the background and $f_0(980)$ resonance contributions in the ${\pi }^{+}{\pi }^{-}$ invariant mass region below the $K^{+}{K}^{-}$ threshold.

We report on the search for the rare decays $B^{+}\to D^{(*)+}{K}_S^0$ in approximately $226\times {10}^6$ ${\rm Y}(4S)\to B\overline{B}$ decays collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at SLAC. We do not observe any significant signal and we set 90% confidence-level upper limits on the branching fractions, $\mathcal{B}(B^{+}\to D^{+}{K}^0)<0.5\times {10}^{-5}$ and $\mathcal{B}(B^{+}\to D^{*+}{K}^0)<0.9\times {10}^{-5}$.

The analysis of geometric phases associated with level crossing is reduced to the familiar diagonalization of the Hamiltonian in the second quantized formulation. A hidden local gauge symmetry, which is associated with the arbitrariness of the phase choice of a complete orthonormal basis set, becomes explicit in this formulation (in particular, in the adiabatic approximation) and specifies physical observables. The choice of a basis set which specifies the coordinate in the functional space is arbitrary in the second quantization, and a subclass of coordinate transformations, which keeps the form of the action invariant, is recognized as the gauge symmetry. We discuss the implications of this hidden local gauge symmetry in detail by analyzing geometric phases for cyclic and noncyclic evolutions. It is shown that the hidden local symmetry provides a basic concept alternative to the notion of holonomy to analyze geometric phases and that the analysis based on the hidden local gauge symmetry leads to results consistent with the general prescription of Pancharatnam. We however note an important difference between the geometric phases for cyclic and noncyclic evolutions. We also explain a basic difference between our hidden local gauge symmetry and a gauge symmetry (or equivalence class) used by Aharonov and Anandan in their definition of generalized geometric phases.

In this paper we present a nonsingular black hole model as a possible end-product of gravitational collapse. The depicted spacetime which is type $[II,(II)]$, by Petrov classification, is an exact solution of the Einstein equations and contains two horizons. The equation of state $p_r(\rho )$ in the radial direction, is a well-behaved function of the density $\rho (r)$ and smoothly reproduces vacuumlike behavior near $r=0$ while tending to a polytrope at larger $r$, low $\rho$ values. The final equilibrium configuration comprises a de Sitter-like inner core surrounded by a family of 2-surfaces $\Sigma$ of matter fields with variable equation of state. The fields are all concentrated in the vicinity of the radial center $r=0$. The solution depicts a spacetime that is asymptotically Schwarzschild at large $r$, while it becomes de Sitter-like as $r\to 0$. Possible physical interpretations of the macro-state of the black hole interior in the model are offered. We find that the possible state admits two equally viable interpretations, namely, either a quintessential intermediary region or a phase transition in which a two-fluid system is in both dynamic and thermodynamic equilibrium. We estimate the ratio of pure matter present to the total energy and in both cases find it to be virtually the same, being $\sim 0.83$. Finally, the well-behaved dependence of the density and pressure on the radial coordinate provides some insight on dealing with the information loss paradox.

While large scale cosmic microwave background (CMB) anisotropies involve a combination of the scalar and tensor fluctuations, the scalar amplitude can be independently determined through the CMB-galaxy cross correlation. Using recently measured cross correlation amplitudes, arising from the cross correlation between galaxies and the integrated Sachs-Wolfe (ISW) effect in CMB anisotropies, we obtain a constraint $r<0.5$ at 68% confidence level on the tensor-to-scalar fluctuation amplitude ratio. The data also allow us to exclude gravity waves at a level of a few percent, relative to the density field, in a low-Lambda dominated universe (${\Omega }_{\Lambda }\sim 0.5$). In future, joining cross correlation ISW measurements, which captures cosmological parameter information, with independent determinations of the matter density and CMB anisotropy power spectrum, may constrain the tensor-to-scalar ratio to a level above 0.05. This value is the ultimate limit on tensor-to-scalar ratio from temperature anisotropy maps when all other cosmological parameters except for the tensor amplitude are known and the combination with CMB-galaxy correlation allows this limit to be reached easily be accounting for degeneracies in certain cosmological parameters.

We report on further SLAC measurements of the Askaryan effect: coherent radio emission from charge asymmetry in electromagnetic cascades. We used synthetic rock salt as the dielectric medium, with cascades produced by GeV bremsstrahlung photons at the Final Focus Test Beam. We extend our prior discovery measurements to a wider range of parameter space and explore the effect in a dielectric medium of great potential interest to large-scale ultra-high-energy neutrino detectors: rock salt (halite), which occurs naturally in high purity formations containing in many cases hundreds of ${\mathrm{km}}^3$ of water-equivalent mass. We observed strong coherent pulsed radio emission over a frequency band from 0.2–15 GHz. A grid of embedded dual-polarization antennas was used to confirm the high degree of linear polarization and track the change of direction of the electric-field vector with azimuth around the shower. Coherence was observed over 4 orders of magnitude of shower energy. The frequency dependence of the radiation was tested over 2 orders of magnitude of UHF and microwave frequencies. We have also made the first observations of coherent transition radiation from the Askaryan charge excess, and the result agrees well with theoretical predictions. Based on these results we have performed a detailed and conservative simulation of a realistic GZK neutrino telescope array within a salt dome, and we find it capable of detecting 10 or more contained events per year from even the most conservative GZK neutrino models.

The matched filtering technique is used to search for gravitational wave signals of a known form in the data taken by ground-based detectors. However, the analyzed data contains a number of artifacts arising from various broad-band transients (glitches) of instrumental or environmental origin which can appear with high signal-to-noise ratio on the matched filtering output. This paper describes several techniques to discriminate genuine events from the false ones, based on our knowledge of the signals we look for. Starting with the ${\chi }^2$ discriminator, we show how it may be optimized for free parameters. We then introduce several alternative vetoing statistics and discuss their performance using data from the GEO 600 detector.

The existing experimental data on total cross sections for hadron production in $e^{+}{e}^{-}$ annihilation in the resonance region $\sqrt{s}=3.8-4.8\mathrm{GeV}$, usually presented in terms of the parameter $R$, are critically examined. It is shown that the Crystal Ball and BES measurements are in excellent agreement, and their analysis leads to consistent resonance parameters for the three vector resonances above the $D\overline{D}$ threshold. The results for the widths are found to be considerably different from the presently adopted values, and have much smaller errors.

In a SUSY GUT seesaw scenario, the largeness of the atmospheric neutrino mixing can reflect itself into an enhanced flavor changing mixing of beauty and strange right-handed scalar quarks. If the $CP$ violating phase in such down-type squark $RR$ insertion is the main source of $CP$ asymmetry in $B_d\to \varphi K_S$ and the gluino contributions to $K^0$–$\overline{K^0}$ and $B^0$–$\overline{B^0}$ mixing are negligible, there is a correlation between Re (${ϵ}^{\prime }/{ϵ}_K$) and $B_d\to \varphi K_S$ $CP$ asymmetry, in addition to that with the strange quark CEDM. The current data on Re (${ϵ}^{\prime }/{ϵ}_K)=(16.7\pm 2.6)\times {10}^{-4}$ imply that $S_{\varphi K}$ should be greater than $\sim 0.5(0.25)$ for $\mu \tan \beta =1(5)$ TeV, assuming the $RR$ dominance in $b\to s$ transition and the minimal supergravity type boundary conditions for soft parameters.

In this note we examine the properties of deconstructed Higgsless models for the case of a fermion whose $SU(2)$ properties arise from delocalization over many sites of the deconstructed lattice. We derive expressions for the correlation functions and use these to establish a generalized consistency relation among correlation functions. We discuss the form of the $W$ boson wavefunction and show that if the probability distribution of the delocalized fermions is appropriately related to the $W$ wavefunction, then deviations in precision electroweak parameters are minimized. In particular, we show that this “ideal fermion delocalization” results in the vanishing of three of the four leading zero-momentum electroweak parameters defined by Barbieri et al. We then discuss ideal fermion delocalization in the context of two continuum Higgsless models, one in Anti-deSitter space and one in flat space. Our results may be applied to any Higgsless linear moose model with multiple $SU(2)$ groups, including those with only a few extra vector bosons.

We calculate numerically the phase diagram of the three-flavor Nambu–Jona-Lasinio model at zero and finite temperature as a function of the up, down, and strange quark chemical potentials. We focus on the competition between pseudoscalar condensation and color superconductivity. We find that the two types of phases are separated by first-order transitions.

We study the resummation of large logarithmic perturbative corrections to the partonic cross sections relevant for the process $pp\to \gamma X$ at high transverse momentum of the photon. These corrections arise near the threshold for the partonic reaction and are associated with soft-gluon emission. We especially focus on the resummation effects for the contribution to the cross section where the photon is produced in jet fragmentation. Previous calculations in perturbation theory at fixed order have established that this contribution is a subdominant part of the cross section. We find, however, that it is subject to much larger resummation effects than the direct (nonfragmentation) piece and therefore appears to be a significant contribution in the fixed-target regime, not much suppressed with respect to the direct part. Inclusion of threshold resummation for the fragmentation piece leads to some improvement in comparisons between theoretical calculations and experimental data.

The main contribution to the radiative $B\to K^{*}\gamma$ mode is from penguin operators which are quantum corrections. Thus, this mode may be useful in the search for physics beyond the standard model. In this paper, we compute the branching ratio, direct $CP$ asymmetry, and isospin breaking effects within the standard model in the framework of perturbative QCD, and discuss how new physics might show up in this decay.

We calculate the expectation value of the stress-energy tensor for a massless dilaton-coupled 2D scalar field propagating on an extremal Reissner-Nordström black hole formed by the collapse of a timelike shell, showing its regularity on the horizon.

We find the constraints from Wilkinson microwave anisotropy probe (WMAP) and Sloan digital sky survey (SDSS) data on the fraction of cosmological fluctuations sourced by local cosmic strings using a Markov Chain Monte Carlo (MCMC) analysis. In addition to varying the usual 6 cosmological parameters and the string tension ($\mu$), we also varied the amount of small-scale structure on the strings. Our results indicate that cosmic strings can account for up to 7 (14)% of the total power of the microwave anisotropy at 68 (95)% confidence level. The corresponding bound on the string mass per unit length, within our string model, is $G\mu <3.4(5)\times {10}^{-7}$ at 68 (95)% C.L. We also calculate the $B$-type polarization spectra sourced by cosmic strings and discuss the prospects of their detection.

At the classical level, two-dimensional dilaton gravity coupled to an abelian gauge field has charged black hole solutions, which have much in common with four-dimensional Reissner-Nordström black holes, including multiple asymptotic regions, timelike curvature singularities, and Cauchy horizons. The black hole spacetime is, however, significantly modified by quantum effects, which can be systematically studied in this two-dimensional context. In particular, the back-reaction on the geometry due to pair-creation of charged fermions destabilizes the inner horizon and replaces it with a spacelike curvature singularity. The semiclassical geometry has the same global topology as an electrically neutral black hole.

We introduce a random matrix model with the symmetries of QCD with two colors at nonzero isospin and baryon chemical potentials and temperature. We analyze its phase diagram and find phases with condensation of pion and diquark states in addition to the phases with spontaneously broken chiral symmetries. In the limit of small chemical potentials and quark masses, we reproduce the mean field results obtained from chiral Lagrangians. As in the case of QCD with three colors, the presence of two chemical potentials breaks the flavor symmetry and leads to phases that are characterized by different behaviors of the chiral condensates for each flavor. In particular, the phase diagram we obtain is similar to QCD with three colors and three flavors of quarks of equal masses at zero baryon chemical potential and nonzero isospin and strange chemical potentials. A tricritical point of the superfluid transitions found in lattice calculations and from an analysis in terms of chiral Lagrangians does not appear in the random matrix model. Remarkably, at fixed isospin chemical potential, for the regions outside of the superfluid phases, the phase diagrams in the temperature—baryon chemical potential plane for two colors and three colors are qualitatively the same.

As computing resources are limited, choosing the parameters for a full lattice QCD simulation always amounts to a compromise between the competing objectives of a lattice spacing as small, quarks as light, and a volume as large as possible. Aiming to push unquenched simulations with the Wilson action towards the computationally expensive regime of small quark masses we address the question whether one can possibly save computing time by extrapolating results from small lattices to the infinite volume, prior to the usual chiral and continuum extrapolations. In the present work the systematic volume dependence of simulated pion and nucleon masses is investigated and compared with a long-standing analytic formula by Lüscher and with results from chiral perturbation theory (ChPT). We analyze data from hybrid Monte Carlo simulations with the standard (unimproved) two-flavor Wilson action at two different lattice spacings of $a\approx 0.08$ and 0.13 fm. The quark masses considered correspond to approximately 85% and 50% (at the smaller $a$) and 36% (at the larger $a$) of the strange quark mass. At each quark mass we study at least three different lattices with $L/a=10$ to 24 sites in the spatial directions ($L=0.85–2.08\mathrm{fm}$). We find that an exponential ansatz fits the volume dependence of the pion masses well, but with a coefficient about an order of magnitude larger than the theoretical leading-order prediction. In the case of the nucleon we observe a remarkably good agreement between our lattice data and a recent formula from relativistic baryon ChPT.

The notion of semiclassical states is first sharpened by clarifying two issues that appear to have been overlooked in the literature. Systems with linear and quadratic constraints are then considered and the group averaging procedure is applied to kinematical coherent states to obtain physical semiclassical states. In the specific examples considered, the technique turns out to be surprisingly efficient, suggesting that it may well be possible to use kinematical structures to analyze the semiclassical behavior of physical states of an interesting class of constrained systems.