18978265
Orbits in a Neighboring Dwarf Galaxy According to MOND
We study the orbits in the MOND theory within a dwarf galaxy of mass Md ∼ 108M⊙ at a distance of ∼ 100kpc from a neighboring galaxy of mass Mg = 5 × 1011M⊙, such as ours. It is assumed that a second mass m << Md is gravitationally bound to Md by a previously calculated potential for the MOND theory. This potential is obtained for a free falling mass Md in a constant external gravitational acceleration field ∇φg. The numerical technique of surfaces of section is used to study the stability of the phase-space orbits in the dwarf galaxy. Equatorial orbits with sufficiently small eccentricities e < 0.65 are found to be stable with respect to small changes in the initial conditions. (The equatorial plane is perpendicular to the direction of ∇φg, which is along the line joining Md and Mg.) For decreasing values of the conserved component of the angular momentum, in the direction of ∇φg, equatorial stability is lost. Subject headings: cosmology — gravitation — galaxies: dwarf.
118472353
BIANCHI I SOLUTIONS OF EFFECTIVE QUADRATIC GRAVITY
It is believed that soon after the Planck time, Einstein's general relativity theory should be corrected to an effective quadratic theory. Numerical solutions for the anisotropic generalization of the Friedmann "flat" model E3 for this effective gravity are given. It must be emphasized that although numeric, these solutions are exact in the sense that they depend only on the precision of the machine. The solutions are identified asymptotically in a certain sense. It is found solutions which asymptote de Sitter space, Minkowski space and a singularity. This work is a generalization for nondiagonal spatial metrics of a previous result obtained by one of us and a collaborator for Bianchi I spaces.
119495652
Casimir energy in a small volume multiply connected static hyperbolic preinflationary universe
A few years ago, Cornish, Spergel and Starkman (CSS) suggested that a multiply connected ''small'' universe could allow for classical chaotic mixing as a preinflationary homogenization process. The smaller the volume, the more important the process. Also, a smaller universe has a greater probability of being spontaneously created. Previously DeWitt, Hart and Isham (DHI) calculated the Casimir energy for static multiply connected flat space-times. Because of the interest in small volume hyperbolic universes (e.g., CSS), we generalize the DHI calculation by making a numerical investigation of the Casimir energy for a conformally coupled, massive scalar field in a static universe, whose spatial sections are the Weeks manifold, the smallest universe of negative curvature known. In spite of being a numerical calculation, our result is in fact exact. It is shown that there is spontaneous vacuum excitation of low multipolar components.
119377344
Casimir Effect in Compact Universes
The Casimir effect in compact hyperbolic Universes was numerically obtained in previous publications. In this talk, I expose these results.
119193340
The concept of phenomenological light-front wave functions -- Regge improved diquark model predictions
We introduce a classification scheme for parton distribution models and we model generalized parton distributions (GPDs), their form factors, and parton distribution functions (PDFs), integrated and unintegrated ones, in terms of unintegrated double distributions that are obtained from the parton number conserved overlap of effective light-front wave functions. For a so-called "spherical" model we present general expressions for all twist-two related non-perturbative quantities in terms of one effective light-front wave function, including chiral-odd GPDs. We also discuss the Regge improvement of such quark models from the $s$-channel point of view and study the relations between zero-skewness GPDs and unintegrated PDFs on a more general ground. Finally, we provide a few phenomenological applications that emphasize the role of orbital angular momenta.
84154696
Results from PETRA on the Average Lifetime of B Hadrons
121044718
A Study of Correlations Between Identified Charged Hadrons in Hadronic Z0 Decays
We present a preliminary study of correlations in rapidity between pairs of identified charged pions, kaons and protons in the SLD data. Details of short-range charge correlations between all combinations of these hadron species are used to study the locality of quantum number conservation, and suggest local charge ordering along the entire hadronization chain. A strong long-range K{sup +}K{sup -} correlation is observed at high-momentum and weaker long-range {pi}{sup +}-{pi}{sup -}, {pi}{sup +}-K{sup -} and p-K{sup -} correlations are observed in light flavor events, providing new information on leading particle production in u, d and s jets. The long-range correlations observed in c{bar c} and b{bar b} events are markedly different and consistent with expectations based on known decay properties of the leading heavy hadrons. The SLC electron beam polarization is used to tag the quark hemisphere in each event, allowing the first study of rapidities signed relative to the quark (vs. antiquark) direction. Distributions of ordered, signed rapidity differences provide a new probes of the fragmentation process, including the first direct observation of baryon number ordering along the q {yields} {bar q} axis.
123690218
Identified hadron production at SLD and BABAR
We present measurements of identified hadron spectra in $e^+e^-\!\!\rightarrow$ hadrons from the BABAR and SLD experiments at respective c.m. energies of 10.54 GeV and 91.2 GeV. The scaling violations between the two energies are found to be large and described by hadronization models for charged pions, but not for heavier hadrons. SLD measurements show large differences between $b\bar{b}$, $c\bar{c}$ and light-flavor events that are qualitatively consistent with expectations. The light flavor events are somewhat more consistent with the predictions of MLLA QCD than are events of all flavors, but a discrepancy in the mass dependence remains. SLD have made several new and/or improved measurements of light leading particle production, paving the way for future tagging of u, d and s jets. They have also made a unique study of signed rapidity correlations, showing direct evidence for charge ordering of protons along the quark-antiquark axis.
119092137
Physics results from SLD using the CRID
Abstract We review recent Z 0 physics results from SLD that use CRID particle identification. The performance of the detector and likelihood method are described briefly. Several hadronization measurements are presented, including identified hadron production in events of different primary flavors, leading hadron production, and new correlation studies sensitive to details of both leading and nonleading hadron production. Identified K ± have been used in conjunction with precision vertexing to study charmless and doubly charmed B-hadron decays. This combination has also been used to tag b, b , c and c jets, yielding precise measurements of B 0 - B 0 mixing and of the asymmetric couplings A b and A c . Identified K ± and Λ 0 / Λ 0 have been used to tag s and s jets, yielding a measurement of A s . The clean identified particle samples provided efficiently by the CRID allow the purities of these tags to be measured from the data, an essential ingredient for precision physics.