Samples of 9200 muon-neutrino and 3800 muon-antineutrino interactions on nuclei were obtained with the fine-grain calorimeter of the CHARM Collaboration at the CERN 200 GeV narrow-band neutrino beam. The interactions were classified as either neutral-current or charged-current processes on an event-by-event basis. Neutral-current and charged-current cross sections in neutrino and antineutrino interactions are presented. From these results we deduce a statistically significant contribution of right-handed coupling to the neutral hadronic current, and a value of the electroweak mixing angle corresponding to sin 2 θ = 0.220 ± 0.014.
Measured charged current total cross section.
Measured charged current total cross section.
No description provided.
The processes e + e − → e + e − and μ + μ − have been studied at PETRA using the JADE detector. The data, which were collected at s -values of up to 1300 GeV 2 have been analysed in terms of an electro-weak extension of QED to obtain values for the weak vector and axial vector couplings in the lepton sector. The values obtained agree with the predictions of the standard Salam-Weinberg model and the data are further analysed in terms of this model to obtain the limits 0.10 < sin 2 ϑ w < 0.40 (68% CL). The mass of the neutral weak gauge boson is deduced to be greater than 51 GeV/ c 2 .
No description provided.
No description provided.
No description provided.
Total cross sections for reactions e + e − → π + π − π 0 , π + π − π 0 , 2 π + 2 π − π 0 , 2 π + 2 π − 2 π 0 , 3 π + 3 π − have been measured in the total c.m. energy range 1.42–2.20 GeV. Partial R = σ had / σ σ + μ − values for two and four produced charged pions, and cross sections for positive and negative G -parity states are also reported.
THE CROSS SECTIONS FOR PRODUCING AN ODD OR EVEN NUMBER OF PIONS CORRESPOND TO NEGATIVE OR POSITIVE G-PARITY FINAL STATES. CROSS SECTION FOR E+ E- --> PI+ PI+ PI+ PI- PI- PI- IS LESS THAN ABOUT 2 NB IN THIS ENERGY RANGE.
No description provided.
Diffractive production of the 3 π system has been studied at 63 and 94 GeV using a two magnet spectrometer with high, uniform acceptance. The total number of events used in the analysis is ∼600 000. The A 2 meson is shown to be diffractively produced. The existence of a resonant component in both the 1 + and 2 − enhancements is established and resonance parameters for the corresponding A 1 and A 3 mesons are given. There are several indications in the data of states which would correspond to radial excitations in the quark model.
SEE C. DAUM ET AL., PL 89B, 276 (1980) (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+486> RED = 486 </a>), AND THE RECORD (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+420> RED = 420 </a>) OF THE GENEVA CONFERENCE PREPRINT, B. ALPER ET AL. (1979).
SEE C. DAUM ET AL., PL 89B, 281 (1980) (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+487> RED = 487 </a>), AND THE RECORD (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+419> RED = 419 </a>) OF THE GENEVA CONFERENCE PREPRINT, G. THOMPSON ET AL. (1979).
SEE C. DAUM ET AL., PL 89B, 285 (1980) (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+488> RED = 488 </a>), AND THE RECORD (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+421> RED = 421 </a>) OF THE GENEVA CONFERENCE PREPRINT, B. ALPER ET AL. (1979).
None
DATA FOR POSITIVE RAPIDITY OF CHARGED PARTICLES IN FINAL STATE.
None
No description provided.
No description provided.
No description provided.
A tagged photon beam and multiparticle spectrometer have been used to measure the backward photoproduction process γp → Δ ++ π − . The energy dependence of the production cross section between 2.8 and 4.8 GeV is studied and found to exhibit shrinkage in excess of that expected for Δ σ dominance. An interpretation of the production mechanism in terms of an incoherent mixture of Δ σ exchange and a “hard scattering” contribution is presented.
No description provided.
Measurements of energy-energy correlations in hadronic final states produced in e + e − annihilation at c.m. energies between 7.7 and 31.6 GeV are presented. The data are compared to perturbative QCD predictions. Good qualitative agreement above 20 GeV c.m. energy is found. The importance of non-perturbative effects is discussed, as well as the detailed behaviour of the correlation near 180°.
No description provided.
OPPOSITE SIDE ENERGY-ENERGY CORRELATIONS NEAR 180 DEG.
ENERGY-ENERGY CORRELATION INTEGRATED IN THE REGION 60 TO 120 DEG.
The differential cross sections for Bhabha scattering and μ pair production, and the total τ pair cross section as measured by the PLUTO detector at PETRA, have been analyzed to extract information on the weak interaction of leptons. The data are compared with unified gauge theories. Since the observed electroweak effects are still consistent with zero (within errors) we can set experimental limits on neutral current parameters atQ2 values of 950 GeV2. In the framework of the standard SU(2)×U(1) model we find sin2Θw<0.52(95% c.l.). In the context of general singleZo models we can excludeZo masses of less than 40 GeV.
No description provided.
No description provided.
A multi-jet analysis of hadronic final states from e + e − annihilation in the energy range 27 < E cm < 32GeV is presented. The analysis uses a cluster method to identify the jets in a hadronic event. The distribution of the number of jets per event is compared with several models. From the number of identified coplanar three-jet events the strong coupling constant is determined to beα S = 0.15 ± 0.03 (stat. error) ± 0.02 (syst. error). The inferred energy distribution of the most energetic parton is in good agreement with the first-order QCD prediction. A scalar-gluon model is strongly disfavoured. Higher-twist contributions to the three-jet sample are found to be small.
No description provided.
Forum