1646135
THE DIRC COUNTER: A NEW TYPE OF PARTICLE IDENTIFICATION DEVICE FOR B FACTORIES*
A very thin, solid radiator, totally internally reflecting, imaging Cherenkov counter (DIRC) is described. This device is well matched to requirements at an asymmetric e+e- B Factory. the hadronic charged particle identification 1. INTR~IXJ~TI~N Particle identification at a B factory is difficult, and highly constrained by the machine environment and the need for good energy measurement of soft photons in the calorimeter which surrounds the particle identification device [l]. Because of the high beam crossing rate and the potential for large backgrounds, the particle identification detector must be robust and relatively fast. Good r~‘dK separation is required over a wide momentum range between about 0.25 and 4 GeV/c. Most detectors measure dE/dx in the tracking chamber which allows good X/K separation up to about 600 MeV/c, but a specific identification device is required over most of the momentum region [2]. The amount of material in the device should be small (preferably less than 10% LRAD) and should be distributed as close as possible to the calorimeter in order to avoid degradation in the resolution performance of the calorimeter, and the loss of low energy conversion electrons in the magnetic field. In addition, the cost of the high quality calorimeter scales roughly like the radius squared and there will be substantial cost savings if the particle identification device can be made thin.
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.
84154696
Results from PETRA on the Average Lifetime of B Hadrons
125346382
Precision tests of the Standard Model at electron colliders
We review electroweak physics studies in high-energy e + e − collisions at CERN and SLAC. Studies of couplings of the Z 0 boson to many of the fundamental fermions are now quite detailed, and those of the W ± bosons are well under way. Sensitivity to radiative corrections due to the massive top quark, the as yet undiscovered Higgs boson, and new physics at the TeV scale has been achieved. The Standard Model is consistent with all data, although further studies are indicated in several areas. In the absence of new physics, the Higgs mass is limited to <188 GeV/c2 at 95% C.L.
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.
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.
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.
119420912
Casimir energy in multiply connected static hyperbolic universes
We generalize a previously obtained result for the case of a few other static hyperbolic universes with manifolds of nontrivial topology as spatial sections.