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.
84154696
Results from PETRA on the Average Lifetime of B Hadrons
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.
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.
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.
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.
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.
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
13486962
Wave functions, evolution equations and evolution kernels from light ray operators of QCD
The widely used nonperturbative wave functions and distribution functions of QCD are determined as matrix elements of light-ray operators. These operators appear as large momentum limit of non-local hadron operators or as summed up local operators in light-cone expansions. Nonforward one-particle matrix elements of such operators lead to new distribution amplitudes describing both hadrons simultaneously. These distribution functions depend besides other variables on two scaling variables. They are applied for the description of exclusive virtual Compton scattering in the Bjorken region near forward direction and the two meson production process. The evolution equations for these distribution amplitudes are derived on the basis of the renormalization group equation of the considered operators. This includes that also the evolution kernels follow from the anomalous dimensions of these operators. Relations between different evolution kernels (especially the Altarelli-Parisi and the Brodsky-Lepage kernels) are derived and explicitly checked for the existing two-loop calculations of QCD. Technical basis of these results are support and analytically properties of the anomalous dimensions of light-ray operators obtained with the help of the α-representation of Green's functions.