The newly observed resonances $D_{s_1}^{*}$ and $D_{s_0}$ are discussed in a potential model. The relationship between the mass difference between the p states $D_{s_1}^{*}{(1\mathrm{}}^{+}{),D}_{s_0}{(0\mathrm{}}^{+})$ and the s states $D_s^{*}{(1\mathrm{}}^{-}{),D}_s{(0\mathrm{}}^{-})$ is also examined. Some remarks about the states $D_{{}_1}^{*}{(1\mathrm{}}^{+})$ and $D_{{}_0}{(0\mathrm{}}^{+})$ in the nonstrange sectors are also made.

We calculate the branching ratios of $\overrightarrow{B}{K}_1\gamma$ at next-to-leading order (NLO) of ${\alpha }_s$ where $K_1$ is the orbitally excited axial vector meson. The NLO decay amplitude is divided into the vertex correction and the hard spectator interaction part. The one is proportional to the weak form factor of $\overrightarrow{B}{K}_1$ transition while the other is a convolution between light-cone distribution amplitudes and the hard scattering kernel. Using the light-cone sum rule results for the form factor, we have $\mathcal{B}(B^0\to K_1^0\mathrm{}(1270\left)\mathrm{}\gamma \right)=(0.828\mathrm{}\pm 0.335)\times {10}^{-5}$ and $\mathcal{B}(B^0\to K_1^0\mathrm{}(1400\left)\mathrm{}\gamma \right)=(0.393\mathrm{}\pm 0.151)\times {10}^{-5}.$

We analyze the end-point region of the photon spectrum in semi-inclusive radiative decays of very heavy quarkonium $\left(m{\alpha }_{\mathrm{s}}^2\gg {\Lambda }_{\mathrm{QCD}}\right).\mathrm{}$ We discuss the interplay of the scales arising in the soft-collinear effective theory, m, $m(1\mathrm{}-{z)}^{1/2},$ and $m\left(1\mathrm{}-z\right)$ for z close to 1, with the scales of heavy quarkonium systems in the weak coupling regime, m, $m{\alpha }_{\mathrm{s}},$ and $m{\alpha }_{\mathrm{s}}^2.$ For $1-z\sim {\alpha }_{\mathrm{s}}^2$ only collinear and (ultra)soft modes are seen to be relevant, but the recently discovered soft-collinear modes show up for $1-z\ll {\alpha }_{\mathrm{s}}^2.$ The S- and P-wave octet shape functions are calculated. When they are included in the analysis of the photon spectrum of the ${\rm Y}\mathrm{}\left(1S\right)\mathrm{}$ system, the agreement with data in the end-point region becomes excellent. The nonrelativistic QCD matrix elements $〈1^3{S}_1|O_8{(}^1{S}_0)|1^3{S}_1〉$ and $〈1^3{S}_1|O_8{(}^3{P}_J)|1^3{S}_1〉$ are also obtained.

Previously published CTEQ6 parton distributions adopt the conventional zero-mass parton scheme since the corresponding hard cross sections are universally available. For precision observables which are sensitive to charm and bottom quark mass effects, we provide in this paper an improved CTEQ6HQ parton distribution set determined in the more general variable flavor number scheme that incorporates heavy flavor mass effects. We describe in detail the QCD scheme and analysis procedure used, examine the predominant features of the new distributions, and compare them with previous distributions.

The lowest order radiative corrections to the width and spectra of the radiative $\pi e2\mathrm{}$ decay are calculated. We take into account the virtual photon emission contribution as well as soft and hard real photon emission contributions. The result turns out to be consistent with the standard Drell-Yan picture for the width and spectra in the leading logarithmical approximation which permits us to generalize it to all orders of perturbation theory. Explicit expressions of nonleading contributions are obtained. The contribution of the short distance is found to be in agreement with standard model predictions. It is presented as a general normalization factor. We check the validity of the Kinoshita-Lee-Nauenberg theorem about the cancellation in the total width of the mass singularities at the zero limit of the electron mass. We discuss the results of the previous papers devoted to this problem. The Dalitz plot distribution is illustrated numerically.

It is shown that the weak phase $\gamma \equiv \arg \left(-V_{\mathrm{ud}}{V}_{\mathrm{ub}}^{*}{V}_{\mathrm{cb}}{V}_{\mathrm{cd}}^{*}\right)$ can be determined using only untagged decays $B^0/B^0\to {\mathrm{DK}}_S.$ In order to reduce the uncertainty in $\gamma ,$ we suggest combining information from $B^{\pm }\to {\mathrm{DK}}^{\pm }$ and from untagged $B^0$ decays, where the D meson is observed in common decay modes. Theoretical assumptions, which may further reduce the statistical error, are also discussed.

The Homestake result is about $\sim 2\sigma$ lower than the Ar-production rate, $Q_{\mathrm{Ar}},$ predicted by the large mixing angle (LMA) Mikheyev-Smirnov-Wolfenstein solution of the solar neutrino problem. Also there is no apparent upturn of the energy spectrum $\left(R\equiv N_{\mathrm{obs}}{/N}_{\mathrm{SSM}}\right)$ at low energies in SNO and Super-Kamiokande. Both these facts can be explained if a light, $\Delta m_{01}^2\sim (0.2\mathrm{}–2)\times {10}^{-5}{\mathrm{eV}}^2,$ sterile neutrino exists which mixes very weakly with active neutrinos: ${\sin }^{2}2\alpha \sim {(10\mathrm{}}^{-5}–{10}^{-3}).\mathrm{}$ We perform both the analytical and numerical study of the conversion effects in the system of two active neutrinos with the LMA parameters and one weakly mixed sterile neutrino. The presence of sterile neutrino leads to a dip in the survival probability in the intermediate energy range $E=(0.5\mathrm{}–5)\mathrm{MeV}$ thus suppressing the Be, or/and pep, CNO, as well as B electron neutrino fluxes. Apart from diminishing $Q_{\mathrm{Ar}}$ it leads to decrease of the Ge-production rate and may lead to the decrease of the BOREXINO signal as well as the CC/NC ratio at SNO. Future studies of the solar neutrinos by SNO, SK, BOREXINO, and KamLAND as well as by the new low energy experiments will allow us to check this possibility.

Experiment E158 at SLAC can measure an azimuthal asymmetry in single-spin, transversely polarized Møller scattering, $e^{-\uparrow }{e}^{-}\to e^{-}{e}^{-},$ which arises from a QED rescattering phase. We recompute the leading-order (one-loop) asymmetry, confirming previous results, and calculate the leading logarithmic QED corrections due to initial-state radiation from the beam and target electrons and due to final-state radiation. The size of these radiative corrections is quite sensitive to experimental details, such as the acceptance in energy and in polar angle of the scattered electron. For E158, the corrections are modest, increasing the parts-per-million asymmetry by roughly 1%.

We report improved measurements of branching fractions for $\overrightarrow{B}K\pi ,$ ${\pi }^{+}{\pi }^{-},$ ${\pi }^{+}{\pi }^0,$ and $K\overline{K}$ decays based on a data sample of 85.0 million $B\overline{B}$ pairs collected at the ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ resonance with the Belle detector at the KEKB $e^{+}{e}^{-}$ storage ring. This data sample is almost three times larger than the sample previously used. We observe clear signals for $\overrightarrow{B}K\pi ,$ ${\pi }^{+}{\pi }^{-},$ and ${\pi }^{+}{\pi }^0$ decays and set upper limits on $\overrightarrow{B}K\overline{K}$ decays. The results can be used to give model-dependent constraints on the CKM angle ${\phi }_3,$ as well as limits on the hadronic uncertainty in the time-dependent analysis of the angle ${\phi }_2.$

We present the results of a search for the production of new particles decaying into two jets in $\overline{p}p$ collisions at $\sqrt{s}=1.8\mathrm{}\mathrm{TeV},$ using the DØ 1992–1995 data set corresponding to ${109\mathrm{}\mathrm{pb}}^{-1}.$ We exclude at the 95% confidence level the production of excited quarks ${(q}^{*})$ with masses below 775 GeV/$c^2,$ the most restrictive limit to date. We also exclude standard-model-like $W^{\prime }$ ${(Z}^{\prime })$ bosons with masses between 300 and 800 GeV/$c^2$ (400 and 640 GeV/$c^2).\mathrm{}$ A $W^{\prime }$ boson with mass $<786\mathrm{}\mathrm{GeV}{/c}^2$ has been excluded by previous measurements, and our lower limit is therefore the most stringent to date.

A relativistic definition of the physically adequate proper reference system of a test observer is suggested within the framework of the parametrized post-Newtonian formalism. According to the nomenclature accepted within the GAIA project this reference system is called the center-of-mass reference system (CoMRS). The interrelation between the suggested definition of the CoMRS and the International Astronomical Union (IAU) Resolutions 2000 on relativity are elucidated. The tetrad representation of the CoMRS at its origin is also explicated. It is demonstrated how to use this tetrad representation to calculate the relation between the observed direction of a light ray and the corresponding coordinate direction in the barycentric celestial reference system of the IAU. It is argued that the kinematically nonrotating CoMRS is the natural choice of the reference system where the attitude of the observer (e.g., of the GAIA satellite) should be modeled. The relativistic equations of rotational motion of a satellite relative to its CoMRS are briefly discussed. A simple algorithm for the attitude description of the satellite is proposed.

We perform a thorough phase-plane analysis of the flow defined by the equations of motion of a FRW Universe filled with a tachyonic fluid plus a barotropic one. The tachyon potential is assumed to be of inverse square form, thus allowing for a two-dimensional autonomous system of equations. The Friedmann constraint, combined with a convenient choice of coordinates, renders the physical state compact. We find the fixed-point solutions, and discuss whether or not they represent attractors. The way the two fluids contribute at late times to the fractional energy density depends on how fast the barotropic fluid redshifts. If it does it fast enough, the tachyonic fluid takes over at late times, but if the opposite happens, the situation will not be completely dominated by the barotropic fluid; instead there will be a residual non-negligible contribution from the tachyon subject to restrictions coming from nucleosynthesis.

We provide a “Baedecker” or travel guide to the directions on the sky where the dark matter annihilation signal may be expected. We calculate the flux of high energy $\gamma$ rays from annihilation of neutralino dark matter in the center of the Milky Way and the three nearest dwarf spheroidals (Sagittarius, Draco, and Canis Major), using realistic models of the dark matter distribution. Other investigators have used cusped dark halo profiles (such as the Navarro-Frenk-White profile) to claim a significant signal. This ignores the substantial astrophysical evidence that the Milky Way is not dark-matter dominated in the inner regions. We show that the annihilation signal from the Galactic Center falls by two orders of magnitude on substituting a cored dark matter density profile for a cusped one. The present and future generation of high energy $\gamma$-ray detectors, whether atmospheric Cherenkov telescopes or space missions such as GLAST, lack the sensitivity to detect any of the monochromatic $\gamma$-ray annihilation lines. The continuum $\gamma$-ray signal above 1 GeV and above 50 GeV may, however, be detectable either from the dwarf spheroidals or from the Milky Way itself. If the density profiles of the dwarf spheroidals are cusped, then the best prospects are for detecting Sagittarius and Canis Major. However, if the dwarf spheroidals have milder, cored profiles, then the annihilation signal is not detectable. For GLAST, an attractive strategy is to exploit the wide field of view and observe the Milky Way at medium latitudes, as suggested by Stoehr et al. This is reasonably robust against changes in the density profile.

The contribution of gravitational neutrino oscillations to the solar neutrino problem is studied by constructing a Dirac Hamiltonian and calculating the corresponding dynamical phase in the vicinity of the Sun in a non-Riemann background Kerr space-time with torsion and nonmetricity. We show that certain components of nonmetricity and the axial as well as nonaxial components of torsion may contribute to neutrino oscillations. We also note that the rotation of the Sun may cause a suppression of transitions among neutrinos. However, the observed solar neutrino deficit could not be explained by any of these effects because they are of the order of Planck scale.

In the gravitational evolution of a cold infinite particle distribution, two-body interactions can be predominant at early times: we show that, by treating the simple case of a Poisson particle distribution in a static universe as an ensemble of isolated two-body systems, one may capture the origin of the first nonlinear correlated structures. The developed power-law-like behavior of the two-point correlation function is then simply related to the functional form of the time-evolved nearest-neighbor probability distribution, whose time dependence can be computed by using the Liouville theorem for the gravitational two-body problem. We then show that a similar dynamical evolution is also found in a large-scale ordered distribution, which has striking similarities to the case of a cosmological cold dark matter simulation which we also consider.

The $8,$ $10,$ and $\overline{10}$ baryon mass spectra as a function of the Skyrme charge e and the $\mathrm{SU}{\mathrm{}\left(3\right)\mathrm{}}_f$ symmetry breaking parameters are given in tabular form. We also estimate the decuplet-octet and the antidecuplet-octet mass difference. A comparison with existing literature is given.

We investigate the possibility of using the center-edge asymmetry to distinguish graviton exchange from other new physics effects at hadron colliders. Specifically, we study lepton-pair production within the Arkani-Hamed–Dimopoulos–Dvali (ADD) and Randall-Sundrum (RS) scenarios. At the Fermilab Tevatron, the graviton-$Z$ interference is the most important contribution to the center-edge asymmetry, whereas at the CERN LHC, the dominant contribution comes from gluon fusion via graviton exchange, which has no analog at $e^{+}{e}^{-}$ colliders. We find that spin-2 and spin-1 exchange can be distinguished up to an ADD cutoff scale, $M_H,$ of about 5 TeV, at the 95% C.L. In the RS scenario, spin-2 resonances can be identified in most of the favored parameter space.

Quantum chromodynamics (QCD) at sufficiently high density is expected to undergo a chiral phase transition. Understanding such a transition is of particular importance for neutron star or quark star physics. In Lagrangian SU(3) lattice gauge theory, the standard approach breaks down at large chemical potential $\mu ,$ due to the complex action problem. The Hamiltonian formulation of lattice QCD does not encounter such a problem. In a previous work, we developed a Hamiltonian approach at finite chemical potential $\mu$ and obtained reasonable results in the strong-coupling regime. In this paper, we extend the previous work to Wilson fermions. We study the chiral behavior and calculate the vacuum energy, chiral condensate, and quark number density, as well as the masses of light hadrons. There is a first-order chiral phase transition at zero temperature.

We calculate the transverse momentum dependence of the medium-induced gluon energy distribution radiated off massive quarks in spatially extended QCD matter. In the absence of a medium, the distribution shows a characteristic mass-dependent depletion of the gluon radiation for angles $\theta <m/E,$ the so-called dead cone effect. Medium modifications of this spectrum are calculated as a function of quark mass m, initial quark energy E, in-medium path length and density. Generically, medium-induced gluon radiation is found to fill the dead cone, but it is reduced at large gluon energies compared to the radiation off light quarks. We quantify the resulting mass dependence for momentum-averaged quantities (gluon energy distribution and average parton energy loss), compare it to simple approximation schemes and discuss its observable consequences for nucleus-nucleus collisions at the BNL RHIC and CERN LHC. In particular, our analysis does not favor the complete disappearance of energy loss effects from leading open charm spectra at the RHIC.