84154696
Results from PETRA on the Average Lifetime of B Hadrons
124860285
Review of c, b and τ Lifetimes from e+e- Experiments
The current status of lifetime measurements of heavy flavored particles by experiments at e + e - colliders and their implications for the standard model are reviewed. This includes the most recent measurents of lifetimes of the tau lepton, the D mesons and B hadrons. The emphasis is on B hadron lifetimes, since there are several new results contributed to this conference. The first use of the B lifetime to tag and study bƃ events is also discussed.
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.
42652971
Hadron Production in Quark and Antiquark Jets
We present a number of jet fragmentation measurements e{sup +}e{sup -} --> hadrons. The ALEPH collaboration measures inclusive rho{sup 0}(770), f{sub 0}(980) and f{sub 2}(1270) production rates, improving the world averages. The SLD collaboration measures pi{sup {+-}}, K{sup {+-}} and p/anti-p production in light-, c- and b-flavor Z{sup 0} decays, as well as leading hadrons in light-quark jets, precisely. The DELPHI collaboration measures the average charged multiplicity in light- and b-flavor events at 183 and 189 GeV, verifying a precise prediction of QCD and excluding flavor-independent fragmentation.
117111758
A study of jet handedness in hadronic Z0 decays
56136446
Hadron production in e+e- annihilation at BaBar, and implication for the muon anomalous magnetic moment.
The BABAR collaboration has an intensive program of studying hadroni c cross sections in lowenergyee collisions, accessible at BABAR via initial-state radiation. Our measurements allow significant improvements in the precision of the predicted v alue of the muon anomalous magnetic moment. These improvements are necessary for shedding ligh t on t e current ∼3.5σ difference between the predicted and experimental values. We have publ ished results on a number of processes with two to six hadrons in the final state. We report her e the results of recent studies of the processese+e−→K+K− ande+e− → 4 hadrons, which constitute the main contribution to the hadronic cross section in the energy region between 1 and 3 Ge V.
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.
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.
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
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.
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.