F. A. Harris

Heavy quarkonium physics

This report is the result of the collaboration and research effort of the Quarkonium Working Group over the last three years. It provides a comprehensive overview of the state of the art in heavy-quarkonium theory and experiment, covering quarkonium spectroscopy, decay, and production, the determination of QCD parameters from quarkonium observables, quarkonia in media, and the effects on quarkonia of physics beyond the Standard Model. An introduction to common theoretical and experimental tools is included. Future opportunities for research in quarkonium physics are also discussed.

Determination of ±s from a differential-jet-multiplicity distribution in e+e- collisions at ss =29 and 91 GeV

We measured the differential jet-multiplicity distribution in {ital e}{sup +}{ital e}{sup {minus}} annihilation with the Mark II detector. This distribution is compared with the second-order QCD prediction and {alpha}{sub {ital s}} is determined to be 0.123{plus minus}0.009{plus minus}0.005 at {radical}{ital s}{approx}{ital M}{sub {ital Z}} (at the SLAC Linear Collider) and 0.149{plus minus}0.002{plus minus}0.007 at {radical}{ital s}=29 GeV (at the SLAC storage ring PEP). The running of {alpha}{sub {ital s}} between these two center-of-mass energies is consistent with the QCD prediction.

The experimental identification of individual particles by the observation of transition radiation in the x-ray region

Abstract Transition radiation in the X-ray region produced by 1.3 GeV/c and 3.0 GeV/c electrons has been detected using multi-wire proportional chambers (MWPC). The radiation was generated in eleven stacks of 100 mylar foils (thickness 1 2 mil. or 1 6 mil. ) each preceding one of eleven MWPC placed in line; two inch thick slabs of styrofoam were also used. The incident particles, electrons or π−-mesons, passed through the MWPC as well as the foils. Results are given on the numbers of transition radiation photons detected, the energy deposition in the chambers and the relativistic rise of ionisation loss in argon and krypton. The distribution in total pulse height obtained with krypton shows a good separation of π−-mesons and electrons at 3 GeV/c.

The external muon identifier for the fermilab 15 ft bubble chamber

Abstract An external muon identifier to aid in the identification of muons produced in neutrino interactions in the Fermilab 15 ft bubble chamber has been constructed. Details of design and analysis procedures are discussed. The spatial resolution and efficiency have been calibrated using muons regenerated by neutrino interactions in material upstream of the bubble chamber. A formalism to describe the statistical significance of muon matches in the identifier is developed and tested using tracks from actual neutrino interactions.

Muon Identification Using Multiwire Proportional Chambers

Abstract Test data are summarized for a muon identifier consisting of iron absorber plates followed by multiwire proportional chambers. Because of the penetrating secondaries that result from hadronic interactions, conventional muon identifiers lacking spatial resolution require many collision lengths to attenuate, and thus to separate incident hadrons from muons. By using multiwire proportional chambers, hadronic interactions can be detected well before the subsequent hadron cascades have been fully absorbed. This permits a substantial reduction in absorber thickness and is important in applications in which the muons originate in a large volume or in which they are to be identified over a large area or large solid angle. A typical result from these tests is that at 3 GeV/c a single multiwire proportional chamber, following only 50 cm of iron, can reject pions with 96±1% efficiency while accepting 96% of the incident muons. An important advantage of this technique is that the performance is expected to be rather independent of energy above a few GeV.

Limits on the neutrino oscillations ν ¯ μ → ν ¯ e and ν ¯ μ → ν ¯ τ using a narrow-band beam

In an exposure of the Fermilab 15-ft bubble chamber to the dichromatic antineutrino beam, 427 nu-bar/sub ..mu../ charged-current interactions were obtained. Taking advantage of the small and well understood background flux of nu-bar/sub e/s in the dichromatic nu-bar/sub ..mu../ beam, upper limits on the rates of antineutrino oscillations are obtained, with the precision limited by statistical rather than systematic errors, in contrast to previous experiments. The 90%-C.L. upper limits obtained for the average oscillation probabilities indicated are P(nu-bar/sub ..mu../..-->..nu-bar/sub e/) ..nu-bar/sub tau/)<4.4 x 10/sup -2/. The mean value of the distance from the neutrino-production point to the bubble chamber divided by the neutrino energy, , is 0.03 m/MeV.

A scenario for high accuracy τ mass measurement at BEPC-II

Scenarios for the τ mass measurement at the upgraded Beijing Electron-Positron Collider (BEPC-II) are studied. A nested minimization procedure is used to optimize the data taking plan. It is found that by using five energy points with the total integrated luminosity of 100 pb−1,the τ mass can be determined with a statistical error of 50 keV.

Search for highly-interacting, fractionally-charged particles in electron-positron annihilation at 29 GeV☆

Abstract We have searched for relativistic, highly-interacting fractionally-charged particles using the free-quark detector at the e + e − storage ring PEP. No convincing events were seen. For an assumed interaction cross section with matter of 100 times geometric, 90% confidence level upper limits on their production relative to e + e − → μ + μ − are between 0.025 and 0.49 depending on quark mass (up to 13 GeV/ c 2 ) and reaction type. These are the first published limits on the production of fractionally charged particles with interaction cross sections of 100 times geometric or larger.

Observation of short-lived particles produced in high energy neutrino interactions

Abstract Examination of a sample of 89 high-energy, neutrino-induced dilepton events produced in the Fermilab 15 ft bubble chamber has resulted in the direct observation of the production and visible semi-leptonic decay of short-lived particles. One charged decay, two neutral decays, and one decay candidate of undetermined charge are found. Assuming these events and the remaining dilepton signal result from D meson decays, we obtain τ D + = 2.5 −1.5 +3.5 × 10 −13 s and τ D 0 = 3.5 −1.7 +3.5 × 10 −13 s, using a maximum likelihood analysis.

Evidence for f0(980)f0(980) production in Χc0 decays

Using a sample of 14 million