18543905
Test of a conceptual prototype of the total internal reflection Cherenkov imaging detector (DIRC) with cosmic muons
The DIRC is a totally internally reflecting Cherenkov imaging detector proposed for particle identification at the asymmetric e/sup +/e/sup -/ B factories. First test results from a conceptual prototype using cosmic muons are reported. The photo-electron yield and the single Cherenkov photon resolution at various track dip angles and positions along the radiator bar have been measured. The results are consistent with estimates and Monte-Carlo simulations. >
17701102
Recent Tests of QCD at SLD
We present selected results on strong interaction physics from the SLD experiment at the SLAC Linear Collider. We report on several new studies of 3- and 4-jet hadronic Z{sup 0} decays, in which jets are identified as quark, antiquark or gluon. The gluon energy spectrum is measured over the full kinematic range, providing an improved test of QCD and limits on anomalous bbg and bbg couplings. The parity violation in Z{sup 0} {yields} b{bar b}g decays is consistent with electroweak theory plus QCD. New tests of T- and CP-conservation at the bbg vertex are performed. An improved measurement of the rate of gluon splitting into b{bar b} pairs yields g{sub b{bar b}} = 0.00244 {+-} 0.00059(stat.) {+-} 0.00034(syst.). We also present a number of new results on jet fragmentation into identified hadrons. The B hadron energy spectrum is measured over the full kinematic range using a new, inclusive technique, allowing stringent tests of predictions for its shape and a precise measurement of 0 corresponds to the quark direction provides additional new insights into fragmentation, including the first direct observation of baryon number ordering along the q{bar q} axis.« less
18652498
Hadron Physics at BaBar
The BABAR experiment at SLAC is designed to measure CP violation in the B meson system, however the very high statistics combined with the different e+ and e− beam energies, the detector design and the open trigger allow a wide variety of spectroscopic measurements. We are beginning to tap this potential via several production mechanisms. Here we present recent results from initial state radiation, hadronic jets, few body B and D hadron decays, and interactions in the detector material. We also summarize measurements relevant to Ds meson spectroscopy, pentaquarks and charmonium spectroscopy from multiple production mechanisms.
120017490
QCD studies of hadronic decays of Z0 bosons by SLD
Z0 bosons have been produced by collisions of longitudinally polarized electrons with unpolarized positrons at the SLAC Linear Collider and their decays have been recorded by the SLD experiment. We present preliminary QCD results based on the first 6000 such decays. We find good agreement between the inclusive properties of these data and the predictions of perturbative QCD plus fragmentation models. The strong coupling, αs, has been measured by three methods: jet rates yield αs(MZ)=0.119±0.002(stat.)±0.003(exp. syst.)±0.014(theor.); energy‐energy correlations yield αs(MZ)=0.121±0.002±0.004±0.0160.009; and the energy‐energy correlation asymmetry gives αs(MZ)=0.108±0.003±0.005±0.0080.003.
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.
119054667
About Starobinsky inflation
It is believed that soon after the Planck era, space-time should have a semiclassical nature. According to this, the escape from the general relativity theory is unavoidable. Two geometric counterterms are needed to regularize the divergences which come from the expected value. These counterterms are responsible for a higher derivative metric gravitation. Starobinsky's idea was that these higher derivatives could mimic a cosmological constant. In this work numerical solutions are considered for general Bianchi I anisotropic space-times in this higher derivative theory. The approach is 'experimental' in the sense that there is no attempt for an analytical investigation of the results. It is shown that for zero cosmological constant {lambda}=0, there are sets of initial conditions which form basins of attraction that asymptote Minkowski space. The complement of this set of initial conditions form basins which are attracted to some singular solutions. It is also shown, for a cosmological constant {lambda}>0, that there are basins of attraction to a specific de Sitter solution. This result is consistent with Starobinsky's initial idea. The complement of this set also forms basins that are attracted to some type of singular solution. Because the singularity is characterized by curvature scalars, it must be stressedmore » that the basin structure obtained is a topological invariant, i.e., coordinate independent.« less
36454783
Casimir energy density in closed hyperbolic universes
The original Casimir effect results from the difference in the vacuum energies of the electromagnetic field, between that in a region of space with boundary conditions and that in the same region without boundary conditions. In this paper we develop the theory of a similar situation, involving a scalar field in spacetimes with closed spatial sections of negative curvature.
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.
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.
118937097
Numerical Bianchi type I solutions in semiclassical gravitation
It is believed that soon after the Planck era, spacetime should have a semiclassical nature. In this context we consider quantum fields propagating in a classical gravitational field and study the backreaction of these fields, using the expected value of the energy-momentum tensor as source of the gravitational field. According to this theory, the escape from general relativity theory is unavoidable. Two geometric counter-term are needed to regularize the divergences which come from the expected value. There is a parameter associated to each counter-term and in this work we found numerical solutions of this theory to particular initial conditions, for general Bianchi Type I spaces. We show that even though there are spurious solutions some of them can be considered physical. These physical solutions include de Sitter and Minkowski that are obtained asymptotically.