W.B. Atwood

Parity Non-Conservation in Inelastic Electron Scattering

Abstract We have measured parity violating asymmetries in the inelastic scattering of longitudinally polarized electrons from deuterium and hydrogen. For deuterium near Q2 = 1.6 (GeV/c)2 the asymmetry is (−9.5 × 10−5)Q2 with statistical and systematic uncertainties each about 10%.

Further measurements of parity non-conservation in inelastic electron scattering☆

Measurements of the y-dependence of the parity nonconserving asymmetries for inelastic electron scattering from deuterium. The measurements cover a range of y values from 0.15 to 0.36 and show only a small y-dependence. The results are in good agreement with the Weinberg-Salam model for sin/sup 2/theta/sub W/ = 0.224 +- 0.020. 20 references.

Inelastic electron scattering from hydrogen at 50° and 60°☆

Abstract Inelastic electron scattering cross sections have been measured for four-momentum transfers between 4.1 GeV 2 and 30.5 GeV 2 . At the large scattering angles of this experiment, the dominant contribution to the cross section comes from the W 1 structure function. In the conventional scaling variables, x and x ′, this structure function does not exhibit scaling behavior, and at fixed x or x ′ it is found to decrease with increasing four-momentum transfer.

Properties of bottom quark jets in e+e- annihilation at 29 GeV☆

Abstract A sample of events enriched with b b production is obtained with the DELCO detector at PEP and is used to measure the mean multiplicity and spectra of charged particles in bottom-quark jets. Bottom-quark jets are found to be significantly softer and more spherical than jets in general hadronic events.

Measurement of the Cabibbo Suppressed Decays

The branching fractions for the Cabibbo-suppressed tau decays are measured using the DELCO detector at PEP. The results, R(tau..-->..K..nu../sub tau/) = (0.59 +- 0.18)% and R(tau..-->..K..nu../sub tau/+n..pi../sup 0/) = (1.71 +- 0.2 9)% including n = 0, are in agreement with the standard theory of sequential leptons and with tau-..mu..-e universality.

\tau \to K

Quantum chromodynamics (QCD) is a precise and complete theory of quarks and gluons that purports to be an ultimate explanation of all strong interaction experiments at all energies, high and low. There are many reasons to hope and expect that it is right. An annual summer institute on particle physics at the Stanford Linear Accelerator Center (SLAC) has for the past nine years provided an excellent forum for the confrontation of high energy theory with experiment. This book is a collection of four lectures originally given at the seventh of these institutes. The lectures explain the development of high energy theory form the parton and quark model to our present understanding of QCD.

\nu_\tau

Abstract Results are presented of an untagged e + e − → e + e − + π + π − experiment performed at PEP with the DELCO detector. In the invariant-mass range 0.7 ⩽ W ππ c 2 , the QED e + e − background is identified and eliminated, and both the π + π − predictions and the μ + μ − and K + K − background substractions are normalized to the measurement of the e e + e − events. The results agree with a simple model of superposition and interference of the f 0 (1270) resonance, produced with helicity 2, with a Born-term continuum. From a fit of the model to the data, the radiative width of the f 0 is determined to be Γ f 0 → γγ = 2.70 ± 0.21 keV.

and

Abstract The forward-backward asymmetry in e + e − annihilation induced by neutral currents allows an effective particle-antiparticle separation. This is used to define a simple CP violating observable. At the Z o resonance, where th production rates are high, polarized electrons may increase the forward-backward asymmetries by up to a factor six. The number of events necessary to establish a CP -violating effect with neutral B mesons is reduced by about an order of magnitude compared with the usual lepton tag method.

\tau \to K

Abstract The forward-backward asymmetry in polarized e + e − annihilation at the Z 0 resonance separates particle from antiparticle. This separation facilitates CP violation measurements in neutral B meson decays. The final states of those decays can either be CP eigenstates or not. This note discusses the CP asymmetries expected for the general final state.

\nu_\tau n \pi^0

The branching fractions for the Cabibbo-suppressed tau decays are measured using the DELCO detector at PEP. The results, R(tau..-->..K..nu../sub tau/) = (0.59 +- 0.18)% and R(tau..-->..K..nu../sub tau/+n..pi../sup 0/) = (1.71 +- 0.2 9)% including n = 0, are in agreement with the standard theory of sequential leptons and with tau-..mu..-e universality.