PROC. 19th INT. CONF. HIGH ENERGY PHYSICS TOKYO, 1978
B 5 Recent Results from the CDHS Experiment
Presented by D. SCHLATTER
CERN
Results are presented on charged current interactions, like-sign dimuon and trimuon production in v- and v-Fe scattering at SPS energies. For details the reader is referred to réf. 1 for the charged current data, and to refs. 2 and 3 for the trimuons.
(3 5±0 15 §1. xFd(x) oc Jx(l —x) • • > and The charged current results are based on a ^(x)oc(l~x)(6-7±0-5). sample of ~ 23,000 neutrino and -6,000 anti- —Scaling violations are observed in the shape neutrino events produced in a narrow band of F2(x) as a function of the neutrino energy beam. The neutrino spectrum extends from 2 and in decreasing F2(x9 Q ) with increasing 30 GeV to 90 GeV for neutrinos from 7r-decays Q2 for x>0.2. and from 90 GeV to 200 GeV for neutrinos —There is agreement (within 10%) of F2 at from K-decays. The detector consists of a low Q2 with the e-d data from SLAC as fiducial mass of 520 tons of magnetized iron, expected by the quark-parton model. sandwiched with scintillators and drift cham —QCD calculations seem to agree with data bers. 2 2 for F2(x9 Q ) from the low Q region (e-d The preliminary results are: data) to high Q2 values (<100 (GeV)2, u 1. The total cross sections per energy data). are (<7totlE») approximately constant in the energy domain 30-200 GeV, with a possible §11. change of 10% from upper to lower energies, Results for multimuon events produced in mainly due to the uncertainty in the K/;r ratio. wide band beams at 350 GeV and 400 GeV The average values are (in units of 10-38 cm2
1 proton energies are presented. GeV- ):«ot/^)=0.62±0.03,«t/£v)-0.30± —The observed like-sign dimuon (jt~ft~~) 0.02 with the ratio events are dominated by charged current v o*Je =0A%±0.02. interactions with additional TT/K decays in 2. The distributions of the inelasticity y the shower. However, we cannot exclude indicate charge symmetry of F2. The value is a prompt signal of (4±2.5) % of the opposite da*/ây/(d
quarks is $F2dx=0.44±0.03 for 30 GeV< a rate of (3.0^0.4)X 10" of single-muon
£<90GeV and $F2dx==0.47±0.05 for 90 event rate. The events are consistent with GeV<£<200 GeV. being due to charged current interactions —The relative contribution of the antiquarks, with the additional production of a muon measured from the ^-distribution in neutrino pair by both hadronic and radiative pro and antineurino interactions, is cesses. No evidence is found for either (q-s+c)l(q+q)=0M±0.04 and heavy-lepton or heavy-quark cascades. iq+s—c)/(q+q)=0A6±0.02 with the ave rage References
q/(q+q)=0A2±0.029 where 1. Inclusive charged current neutrino-iron scattering by T. Hansl et aL, to be published in Nuclear q=u+d-±-s-\-c represents the sum of the quark densities in the nucléon. Physics. 2. T. Hansl et al.: Phys. Letters 77B (1978) 114. 3. The x-distribution for valence quarks and 3. Characteristics of trimuon events observed in for antiquarks is consistent with a parametri- high energy neutrino interactions by T. Hansl zation of et al., to be published in Nuclear Physics.