A search has been made for particles with charge Q = 1 3 , Q = 2 3 and Q = 4 3 produced in e + e − annihilation using the ARGUS detector at the e + e − storage ring DORIS, operating at a centre of mass energy around 10 GeV. No candidate events were found in 84.5 pb −1 of collected data. Upper limits are established for the cross section for the production of fractionally charged particles with masses up to 4 GeV c 2 , improving on previously obtained limits.
Two different models (I and II) are considered (see text).
Properties of the hadron multiplicity distributions in 280 GeV/c μ<sup loc="post">+</sup>p interactions have been investigated. The c.m. energy dependence in the range from 4 to 20 GeV of the total charged multiplicities are presented. No variation faster than logarithmic is seen in the energy range of this experiment. Comparison with νp and <math altimg="si1.gif"><ovl type="bar" style="s">ν</ovl><rm>p</rm></math> data at lower energy has been made and shows good agreement between μ<sup loc="post">+</sup>p and <math altimg="si1.gif"><ovl type="bar" style="s">ν</ovl><rm>p</rm></math> total charged multiplicities. It has been found that the average forward multiplicity (charged hadrons with xF > 0) exceeds the average backward multiplicity (charged hadrons with xF < 0) in the whole energy range and presents a different energy variation. The average forward multiplicity has been compared to e<sup loc="post">+</sup>e<sup loc="post">−</sup> data and shows a similar dependence on energy. Little correlation was observed between the forward and backward multiplicities indicating that the current and target regions fragment almost independently.
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We have measured the deuteron magnetic form factor B(q2) for values of the momentum transfer squared between 7 and 28 fm−2. The data are compared with relativistic and nonrelativistic predictions including meson-exchange-current contributions. Significant disagreement is found for large momentum transfers.
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12,100 νD and 10,500\(\bar vD\) charged current interactions in deuterium measured in the BEBC bubble chamber were used to obtain the complete set of structure functions of proton and neutron. Thex andQ2 dependence of the structure functions of up and down valence quarks and antiquarks are presented and discussed. The Adler and Gross-Llewellyn Smith sum rules have been tested at differentQ2 values. A QCD analysis of the four non singlet structure functionsxF3νN,xuv,xdv andF2νn−F2νp has been performed yielding values ofΛLO between 100 and 300 MeV.
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A supersymmetric extension of the interacting boson model (IBM) is constructed to describe high-spin anomalies in both even- and odd-mass spectra of the Hg, Pt region (190 ⩽ A ⩽ 200). Supergroup chains such as U ( 6 2j + 1 ) ⊃ Osp ( 6 2j + 1 ) ⊃ O (6) × Sp ( 6 2j + 1 )… U ( 6 2j + 1 ) ⊃ U ( 5 2j + 1 ) ⊃ Osp ( 5 2j + 1 )… incorporate a single j -shell fermion in addition to the usual “s” and “d” bosons ( L = 0 and L = 2). The orthosympletic supergroup reflects the strong pairing force in the subspace of the fermion intruder level. The model agrees favourably with experiment and microscopic calculation.
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We report the observation of 21 dimuon events at the CERN p p Collider with the UA1 detector. The events range in invariant dimuon mass from 2 to 22 GeV / c 2 . The properties of these events are given. The bulk of the events are consistent with heavy-flavour production (mainly b b ) with a few candidates for Drell-Yan production. There remain a few events which are difficult to interpret in terms of these processes, in particular two events with isolated, like-sign muons.
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The ρ0-meson spin alignment is studied in p¯p interactions at 22.4 and 12 GeV/c and in the reaction p¯p→2π++2π−+neutrals at 5.7 GeV/c. An essential ρ0-meson spin alignment is observed. The values of the ρ00T element of the ρ0-meson spin-density matrix in the transversity frame are 0.56 ± 0.07, 0.53 ± 0.05, and 0.54 ± 0.04 for the above-mentioned interactions, respectively. An increase of ρ00T with ρ0 transverse momentum is obtained.
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The charged-particle multiplicities of hadronic events deriving from produced bottom or charm quarks have been measured in the Mark II detector at PEP in e+e− annihilation at 29GeV. For events containing one semileptonic and one hadronic weak decay, we find multiplicities of 15.2±0.5±0.7 for bottom and 13.0±0.5±0.8 for charm. The corresponding multiplicities of charged particles accompanying the pair of heavy hadrons are 5.2±0.5±0.9 for bottom, and 8.1±0.5±0.9 for charm.
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The charmonium χ states are observed in both π− and p Be interactions near 200 GeV/c via their radiative decay into J/ψ. The χ(3510) and χ(3555) are produced with roughly equal cross sections in π− collisions while the χ(3555) dominates in p collisions. Simple gluon fusion can account for χ production with incident protons but additional mechanisms are needed for incident π−.
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We have measured the total cross sections of Ω− and Ω¯+ forward (xF>~0) inclusive production in KL0-carbon interactions in the range EK0=80 to 280 GeV to be 3.5±1.4 and 2.4±1.0 μb, respectively. We observe that the xF distributions for both of these states are increasing from xF=0 to xF≈0.6. The p⊥2 distributions are described as an exponential function in p⊥ with an average p⊥2 of 0.540 GeV2/c2.
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