Observation of a direct low-mass e+e− continuum in π-p interactions at 16 GeV/c

The production of prompt electron-positron pairs in 16 GeV/c π^-p collisions has been measured using the LASS spectrometer at SLAC. An excess of events is observed above the estimated contribution of direct and Dalitz decays of known resonances in the kinematic range defined by $\text{0.1?χ?0.45, 0?p}{}_{\mathrm{T}}\text{?0.8}\text{GeV}\text{c}$ and $\text{0.2?M(e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{)?0.7}\text{GeV}\text{c}{}^2$. The excess signal decreases slowly with increasing M, but exhibits very steep χ and p_T² dependence.     

Charge properties of the hadronic system in vp and νp interactions

Charge properties of the hadronic systems from νp and $\text{ν}\text{p}$ scattering in BEBC are studied in the framework of the quark-parto model (QPM). The average charges $\text{〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{<mtext>\nu </mtext>}}$ and $\text{〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{<mtext>\nu </mtext>}}$ of a quark jet and a d-qua jet, respectively, are determined according to two different methods. The difference $\text{〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{\nu }}\text{? 〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{<mtext>\nu </mtext>}}$ is in agreement with e QPM value of 1. Scaling of charge and energy flow in the angular variable λ is demonstrated. The ratios $\text{ΔQ}{}^{\mathrm{<mtext>\nu </mtext>}}\text{/ΔQ}{}^{\mathrm{\nu }}$ of charge flows in νp a $\text{ν}\text{p}$ scattering are in accord with the QPM in both hemispheres.     

Evidence for ψψ production in π− interactions at 150 and 280 GeV/c

From the analysis of multimuon events produced by π^? interactions at 150 and 280 GeV/c in the NA3 spectrometer, we present evidence for the production of two J/ψ mesons in the same interaction (13 events seen, for an expected background of about 0.2 events). Some possible production mechanisms are described and an estimation of the cross section is given.     

A determination of quark weak couplings at petra energies

Data on hadron production by e⁺e^? annihilation at c.m. energies between 12 and 36.6 GeV have been collected using the JADE detector. They have been analysed in terms of single-photon and weak neutral-current exchange assuming production of quark-antiquark pairs with only d, u, s, c and b quarks to produce values for the quark weak neutral-current couplings. A further analysis in terms of the Glashow-Salam-Weinberg theory produced the result, sin²θ_{W = 0.22 ± 0.08}. The theory has therefore been tested in a new energy domain and within the context of the neutral weak couplings of the first, second and third generation quarks.     

Goldstone modes on Wilson's surface

In three-dimensional compact QED in its continuum formulation, Goldstone modes associated with surface fluctuations cause Wilson's surface to wander infinitely far from the minimal surface. On the lattice, this is only true for small coupling, due to the roughening transition.     

Higher moments of the pion multiplicity distribution in proton-proton interactions at 12 and 24 GeV/c

Results on higher moments of the pion multiplicity distribution are presented for pp interactions at 12 and 24 GeV/c incident lab momentum. A simple parametrization for the pion multiplicity distribution is established at 12 and 24 GeV/c and is then used to discuss the energy dependence of higher moments in a range from 4 to about 500 GeV/c incident lab momentum.     

Measurement of the decay ϒ′→ϒπ+π−

We report the first observation of the decay $\text{?′→?π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{→}\text{l}{}^{\mathrm{+}}\text{l}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}$. The 7 events seen yield a branching ratio B(?′→?π⁺π^?)=(19±8)%. A consistent value of B=(26±13)% is obtained from the charged multiplicities of the ?′ and ? decays. Using these values we deduce Γ_tot(?′)=(31⁺¹⁰_?8) keV and B_ee(?′)=(1.8±0.5)%. Furthermore we estimate Γ(?′→gg?)=(10±5) keV in agreement with QCD predictions using vector gluons while one would expect 100 keV with scalar gluons.     

Dimuon events produced in high energy antineutrino interactions observed in BEBC

A study is presented of dimuon events from an exposure of BEBC to a wide band $\text{ν}$ beam from the CERN SPS. These data double the available statistics on $\text{ν}$ induced dilepton events observed in bubble chambers. The relative production rate and V⁰ yield have been measured and found to agree with previous experiments. The analysis of several kinematical variables shows that the gros features of the data agree with the predictions of the GIM model. Some indication exists that part of the signal could be due to quasi elastic production of the “beautiful baryon”, but the statistical significance is too weak to draw definitive conclusions.     

Search for non-strange baryonium states in the baryon exchange reaction K−p → Y0pp at 18.5 GeV/c

Narrow baryonium production in the baryon exchange reactions $\text{K}{}^{\mathrm{?}}\text{p}\text{→ Λ}\text{p}\text{p}$ and $\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{pK}{}^{\mathrm{?}}\text{p}\text{p}$ at 18.5 GeV/c is investigated in a 12 events/nb experiment performed at the CERN Ω′ spectrometer. No narrow structure is observed in the $\text{p}\text{p}$ mass spectra. Upper limits for production of baryonium states are given as a function of $\text{p}\text{p}$ mass.     

Charged pion,kaon, proton and antiproton production in high energy e+e− annihilations

Production of pions, kaons, protons and antiprotons has been studied in e⁺e^? annihilations at 12 and 30 GeV centre of mass energy using time of flight techniques. The fractional yield of charged kaons and baryons appears to rise with outgoing particle momentum. At our highest energy at least 40% of e⁺e^? annihilations into hadrons are estimated to contain baryons.