G.R. Kalbfleisch

Muon pair production in 16 and 22 GeV πCu collisions

Abstract We have measured inclusive muon pair production by 16 and 22 GeV π − on a copper target in a wide aperture magnetic spectrometer. We interpret the data in terms of quark annihilation models and find approximate scaling in the variable τ = M 2 / s over a wide energy range. At large values of τ the yield of μ-pairs produced by π − is ∼ 100 times that produced by protons. This effect can be understood by assuming appropriate quark distributions for π − and p and thus provides experimental insight into the inner structure of these particles.

Formation of a mesonic state in the pp interaction at 1.32 GeV/c☆

Abstract In a bubble chamber experiment, the reaction p p→ϱ o ϱ o π o is found, only at 1.33±0.02 GeV/c, with a cross section of 0.5±0.1 mb. This effect is attributed to the formation of an IG=1− state, π(2190)→→ϱoϱoπo.

Production of Jψ in 16 and 22 GeVπCu collisions

Abstract We have measured the inclusive production of J ψ in 16 and 22 GeV π− copper collisions in a wide aperture magnetic spectrometer. The cross section per Cu nucleus for x > 0 corrected for branching ratio is 64 ± 38 nb at 16 GeV and 196 ± 38 nb at 22 GeV. As threshold is approached, the mean values of the Feynman x distribution increase and the cross section for J ψ production drops steeply. This can be understood in terms of the quark-fusion model where the antiquark content of the pion makes an increasingly significant contribution as M 2 s increases.

pp elastic scattering in the T-meson region

Abstract We have made improved measurements of 43.8 ± 0.8, 41.3 ± 0.4 and 39.3 ± 0.8 mb for the p p elastic cross sections at 1.11, 1.33 and 1.52 GeV/ c laboratory momenta respectively. Sharp forward peaks in the differential cross sections with broad secondary maxima agree with previous observations [3–6]. The forward differential cross sections are (11 ± 3)% above the optical point in agreement with real amplitudes extended from lower momenta using dispersion relations [7]. The elastic cross sections do not show any structure in the s -channel. Backward differential cross sections show the onset of a “third diffraction peak” but no evidence for other structure in agreement with earlier experiments [6, 13].

The magnitude of the parton intrinsic transverse momentum

Abstract We analyze data on the transverse momentum distribution of dimuons produced by 22 GeV and 16 GeV π − incident on a Cu target. We evaluate the quantum chromodynamic lowest order perturbation contributions and also introduce an intrinsic transverse momentum k T on the partons relative to their parent hadrons. The analysis of our data leads to 〈 k T 〉=0.30−0.35 GeV. We discuss our result in comparison with analyses of data at higher energies.

Possibility of experimental determination of the nature of the neutral particles in muon decay

Abstract The nature of the neutral particles from muon decay can be checked through their interactions in the bubble chamber in neutrino exposures of the near future. In particular it can be determined whether the lepton conservation law is additive or multiplicative.

Search for short-lived particles below charm threshold

We have searched for the production by virtual photons of short-lived particles that exhibit muonic decay. We used Brookhavens 10.5 GeV/c muon beam and examined the two and three-muon final states. The sample of 158 trimuon events is due almost entirely to QED tridents. The sample of 673 dimuons can be accounted for in part by asymmetric tridents and in part by the decay of π and K mesons. We obtain an upper limit for the production of other short-lived particles of the order of Bδ < 150 pb/nucleon, where B is the branching ratio for muonic decay. From the trident sample we establish that muons obey Fermi-Dirac statistics at the level of 8 standard deviations.

On the polarization of low mass dimuons produced in hadronic interactions

Abstract We have examined the angular distribution of massive μ+μ− pairs produced in 22 GeV/c π−Cu interactions. We find that the virtual photons which give rise to the process γv→μ+μ− are mainly longitudinally polarized. This contradicts the simple quark-antiquark annihilation model indicating that this is not the dominant production mechanism for the bulk of the data. However, for large fractional momentum of the incident q better agreement with the g q annihilation hypothesis is obtained.

The reactions π±p→pX± (900–1020 MeV) near threshold

Abstract We observe no structure in the X± spectra as our mass resolution of 12 MeV FWHM. Thus the X0(957) of Binnie et al., is determined to be the I = 0 η′. A braid structure at a mass of 976 MeV can be accommodated.

Determination of η′ Parameters from the Reaction K−p ⇒ Λη′K−p⇒Λη′ at 2.2 Ge/c

We present new data on the η′ based on a sample of events obtained from 870,000 pictures of the BNL 31‐inch hydrogen bubble chamber exposed to a 2.2 GeV/c K− beam. We have measured the η′ mass, width, and branching ratios, and we present strong evidence that the quantum numbers of the η′ are J PC = 0 −+ .