About 2000 neutral induced interactions observed inside the hydrogen filled TST in BEBC have been analysed. The data were obtained from an exposure to the v μ wide band beam at the CERN SPS. A separation of these events into charged current, neutral current and neutral hadron induced interactions have been achieved using a multidimensional kinematic analysis. The neutral to charged current cross section ratio for v μ interactions on free protons has been determined avoiding the drastic cuts on the data inherent in previous experiments. The result R P v = 0.47 ± 0.04 is compatible with those measurements and the prediction of the standard SU (2) × U (1) model for sin 2 θ W = 0.18 ± 0.04.
No description provided.
Distributions of the Feynman x variable have been determined for positive and negative pions in charged current neutrino-proton and antineutrino-proton reactions with hadronic energy W > 3 GeV and Bjorken x B > 0.1. The distributions have been corrected for experimental effects such as measurement errors, uncertainties in estimating the neutrino energy and particle misidentification. In the framework of the quark-parton model, the distributions yield information about the fragmentation of forward going u and d quarks and backward going uu and ud diquarks. Approximate Feynman scaling is observed for the invariant Feynman x F distributions. They can be fitted by a power law of the form (1 − | x F |) n as suggested by the dimensional counting rules. Simple isospin relations predicted by the quark-parton model are fulfilled. The fragmentation of diquarks is compared with that of protons into π ± .
No description provided.
No description provided.
We report on a measurement of the process e + e − →e + e − + hadrons, where one of the scattered electrons is detected at large angles, with an average Q 2 of 23 GeV. The results are analysed in terms of the photon structure function F 2 and are compared with QCD predictions.
Data read off graph.
Data read off graph.
Data read off graph.
We present an analysis ofρ0ρ0 production by two photons in theρ0ρ0 invariant mass range from 1.2 to 2.0 GeV. From a study of the angular correlations in the process γγ→ρ0ρ0→π−π+π− we exclude a dominant contribution fromJP=0− or 2− states. The data indicate sizeable contributions fromJP=0+ for four pion massesM4π<1.7 GeV and fromJP=2+ forM4π>1.7 GeV. The data are also well described by a model with isotropic production and uncorrelated isotropic decay of theρ0,s. The cross section stays high below the nominalρ0ρ0 threshold, i.e.M4π<1.5 GeV. The matrix element forρ0ρ0 production is found to decrease steeply with increasingM4π. Upper limits for the couplings of the ι(1440) and Θ(1640) to γγ andρ0ρ0 are given:Γ(ι→γγ)·B(ι→ρ0ρ0)<1.0 keV andΓ(Θ→γγ)
ASSUMING ISOTROPIC RHO0 RHO0 PRODUCTION AND ISOTROPIC RHO DECAY.
CROSS SECTIONS FOR DIFFERENT SPIN-PARITY CONTRIBUTIONS.
We have studied the topologies of hadronic events in e + e - annihilation data taken in the region of the upsilon resonances with the non-magnetic CUSB detectors at CESR. Using a thrust-like variable we compare the decay of ϒ, ϒ′ and ϒPrime; find for ϒ″ a significant excess of high thrust events, which we interpret as evidence for electric dipole transitions.
No description provided.
No description provided.
No description provided.
We report on inclusive K 0 production in the region of the upsilon resonances (9.4–10.6 GeV). The K 0 yield for the resonances and continuum below the B B threshold is found to be constant at 0.82 ± 0.10 K 0 per observed hadronic event. At the ϒ (4S), however, the K 0 yield is significantly higher, 1.58 ± 0.35. This increase in K 0 production and the differential cross section d σ /d p of kaons are consistent with B B decay of the ϒ (4S) resonance with the bottom quarks subsequently decaying primarily into charmed quarks.
No description provided.
ACCEPTANCE CORRECTED INCLUSIVE K0 MOMENTUM DISTRIBUTION AT THE UPSI(10570)0.
Inclusive neutrino and antineutrino charged-current interactions were studied using the electronic detector of the CHARM Collaboration exposed to the narrow-band beam of the CERN SPS. The relative contributions of quarks and antiquarks to the neutrino cross sections were deduced from the differential cross sectionsdσ/d y . The x and Q 2 dependence of the structure functions F 2 and F 3 were measured. Scaling violations were observed, in qualitative agreement with QCD. A value of the mass scale parameter of QCD,Λ = [0.29 ± 0.12 (stat.) ± 0.10 (syst.)] GeV, was deduced in a leading-order approximation, following the method of Buras and Gaemers.
No description provided.
No description provided.
No description provided.
From the analysis of 5630 v υ and of 1372 v π charged current interactions, obtained in the BEBC bubble chamber filled with deuterium and exposed to the CERN wide band antineutrino beam, the ratios of cross section on neutron and photon targets have been measured and found to be R σ ν)/σ v p = 0.51 ± 0.01 (±0.03) , and R σ( ν n )/σ( v p ) = 22.2 ± 0.12 (±0.25) The dependence of these ratios on the x scaling variable shows, in a direct way, that the momentum distribution of the majority quark, u p ( x ) = d n ( x ), is broader than that of the minority quark, u n ( x ) = d p ( x ).
No description provided.
No description provided.
Using data taken at PETRA we present results on deep inelastic electron photon scattering at momentum transfers 1 < Q 2 < 15 GeV 2 . The results are expressed in terms of the photon structure function F 2 and are compared with QCD predictions and “hadronic” models of the photon. The pointlike component of the photon is found to be dominant.
Data read from graph.. Data for W < 3.5 in Berger et al. 1981, PL 99B,287 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1164> RED = 1164 </a>).
PHOTON STRUCTURE FUNCTION. NUMERICAL VALUES OF DATA ON FIGURE SUPPLIED BY W. WAGNER.
In a selected sample of 6770 charged current (CC) events of νp interactions with 〈 E ν 〉 = 43 GeV and 〈W〉 = 4.6 GeV , 359 K 0 , 180 Λ and 13 Λ have been observed, which corresponds to a corrected production rate at least one neutral strange particle in (17.4±0.8)% of the CC events. The ratio of the inclusive Λ to K 0 production cross section is found to be 0.26±0.03. The number of CC events containing at least one K 0 increases with increasing E ν and Q 2 , while the CC events containing at least one Λ remain practically constant. The fractions of the total hadronic energy carried by K 0 and Λ are found to be approximately the same in νp as in ep and μp interactions. In the hadronic c.m.s., the K 0 are produced mostly forwards, the Λ mostly backwards, with asymmetry parameters of +0.32±0.02 and −0.45±0.06, respectively. The total strange particle production cross section is estimated to be (25±4)% of the cross section for production of CC events with W >1.5 GeV and that for charm production (10±2)% of the CC cross section well above charm threshold ( W >3 GeV). The production of the resonances K ∗+ (890) and Σ + (1385) has been observed. The production rate of K ∗+ (890) is comparable to that of D ∗+ (2009), above the corresponding thresholds.
No description provided.
Forum