We present results on charged multiplicity nch=2 and nch>2 muon events produced in e+e− collisions with 〈s12〉=7.3 GeV at 90° to the beams. The background-subtracted inclusive cross section for the nch=2 events is 10.2±5.4 pb/sr, in agreement with the expected contribution from the heavy lepton τ. The cross section for the nch>2 events is 19.0±6.5 pb/sr whereas we expect only 2.9 pb/sr from the τ, indicating that we may be seeing the weak decays of charmed mesons.
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We have measured the difference between the pp total cross sections for parallel and antiparallel longitudinal spin states at beam momenta of 1.0, 1.1, 1.30, 1.58, 1.71, 2.1, and 2.25 GeV/c in a transmission counter experiment. These results reveal new structure in the plab range of 1.0 to 2.5 GeV/c.
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The ϒ′ state has been observed as a narrow resonance at M ( ϒ ′) = 10.02 ± 0.02 GeV in e + e − annihilations, using a NaI and lead-glass detector in the DORIS storage ring at DESY. The ratio Г ee Г had /Г tot of electronic, hadronic, and total widths has been measured to be 0.32 ± 0.13 keV. The parameters of the Г particle have also been determined to be/ M (Г)
The data renormalized to the expected level of continuum based on the ratioof R=sigma(hadrons)/sigma(mu+mu-) = 4.7 at sqrt(s) = 5 GeV.
The data renormalized to the expected level of continuum based on the ratioof R=sigma(hadrons)/sigma(mu+mu-) = 4.7 at sqrt(s) = 5 GeV.
Muon-neutrino and -antineutrino scattering off electrons was detected in a 19-ton Al spark chamber, exposed to the wide-band ν (ν¯) beam from the CERN proton synchrotron. The background was determined experimentally. 11 (10) genuine νμ− (ν¯μ−) e scattering events were found. The respective cross sections are (1.1±0.6)×10−42(Eν/GeV) cm2 and (2.2±1.0)×10−42(Eν/GeV) cm2. The analysis excludes a pure V−A interaction, and makes a pure V or A theory improbable. The data agree well with the Salam-Weinberg model and sin2θW=0.35±0.08.
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A precision measurement of the μ + momentum in π + decay at rest has been made with a magnetic spectrometer. The result is p μ + = (29.7873 ± 0.0014) MeV/c. The consequences of thisresult for the rest masses of the muon neutrino and of the positive pion are discussed.
DECAY AT REST WAS STUDIED.
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Annihilation of e + e − into final states with a single electron has been studied with the PLUTO detector at the DORIS storage ring at CMS energies from 3.6 to 5 GeV. In the sample of 4-prong events without any detected photon we observe 21 events which we assign to the reaction e + e − → τ + τ − → νν e + νϱ 0 π . We obtain a branching ratio for τ + → νϱ 0 π + of 0.050 ± 0.015 with an overall systematic uncertainty of 30%. The data are consistent with the ϱπ coming from an A 1 meson.
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Inclusive ϱ 0 production has been investigated in p p reactions at 22.4 GeV/ c . The total cross section for ϱ 0 production is 8.1 ± 2.0 mb. The average ϱ 0 's per event is 0.17 ± 0.03. The average transverse momentum, as obtained by extrapolation of a fitted simple exponential to the p T 2 distribution, is 0.52 ± 0.12 GeV/ c . The Feynman x and c.m. rapidity distributions show ϱ 0 to be “centrally” produced.
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In this paper we have investigated the properties of the D(1285) and E(1420) meson resonances using the five-body annihilation channels p p → K K πππ obtained in a large statistics experiment (28 events/μb). The analysis favours the 1 + spin-parity assignment for the D(1285) meson. The dominant decay mode of the D(1285) into K K π is found to be δ(970)π. The situation concerning the E(1420) meson remains confused although not inconsistent with previous analyses. Partial cross sections on resonance production are also presented.
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Measurements of inclusive scattering in the target-fragmentation region are extended to higher incident energy. The combined data set shows departures from an approach to the asymptotic scaling limit as A+Bs−12 that are significant even at the highest energies. When these departures are taken into account, the data approach a limit that is consistent with equal cross sections induced by particles and antiparticles and with Pomeron factorization. The corrections to A+Bs−12 are so large that detailed tests of Mueller-Regge relationships are not conclusive.
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The inclusive production of resonances is systematically studied in K + p interactions at 32 GeV/ c . Total production cross sections are given for three baryon resonances, five vector and three 2 + tensor mesons. We also compare the central and fragmentation components of the total production cross sections with quark model predictions.
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