The production of K 0 s, Λs and Λ s has been studied in a 280 GeV muon-proton scattering experiment with almost complete coverage of all kinematic regions. A study is made of the dependence of the multiplicities on the hadronic centre of mass energy, W , and of the Feynman x distributions. It is found that K 0 and Λ production is mostly central and increases strongly with W , whereas Λ production comes mainly from the remnant target system and is only weakly W dependent.
AVERAGE VALUES OF VARIABLES ARE <Q**2>=12GEV**2 , <NU>=76GEV , <W**2>=130GEV**2 , <X BJ>=0.11.
AVERAGE VALUES OF VARIABLES ARE <Q**2>=12GEV**2 , <NU>=76GEV , <W**2>=130GEV**2 , <X BJ>=0.11.
AVERAGE VALUES OF VARIABLES ARE <Q**2>=12GEV**2 , <NU>=76GEV , <W**2>=130GEV**2 , <X BJ>=0.11.
The x dependence of the longitudinal structure function F L was determined with the CHARM neutrino detector exposed to neutrino and antineutrino wide-band beams of the CERN 400 GeV SPS. The results show a clear deviation from the Callan-Gross relation. The amount and the x dependence of this deviation are in agreement with the contribution coming from a finite transverse momentum of the partons in the nucleon if both the intrinsc and perturbative QCD terms are taken into account.
VALUES OF Q**2 FOR EACH POINT IN THE TABLE ARE:- 0.76,3.0,9.3,16.6,18.9.
The proton form factors GE(q2) and GM(q2) are determined at q2 = 75fm−2.
No description provided.
No description provided.
The reaction γγ→K + K − π + π − π 0 has been observed for the first time, using the ARGUS detector at the e + e − storage ring DORIS II at DESY. The cross section shows an enhancement for W γγ close to 3 GeV/ c 2 . Searches for γγ→ωφ and for γγ→φφ leading to this final state, as well as for γγ→φφ→2K + 2K − , have been performed. The derived upper limits for ωφ and φφ production are compatible with q q q q model predictions.
TOPOLOGICAL CROSS SECTION.
95 PCT CL UPPER LIMITS.
Inclusive neutrino and antineutrino charged current interactions were studied in the CHARM detector exposed to neutrino and antineutrino Wide Band Beams of the CERN 400 GeV SPS. The x and Q 2 dependence of the structure functions F 2 and xF 3 and of the antiquark momentum distribution q were determined. The data have been interpreted in terms of QCD theory using the Furmanski-Petronzio method. In this way we have determined Λ LO = [190 −40 +70 ( stat ) ± 70 ( syst .)] MeV and the structure functions of quarks and gluons without specific assumptions on their analytic dependence. The results agree with previous experiments which relied on model assumptions in the analysis. We conclude that the model independent simultaneous analysis of the xF 3 , F 2 , q structure functions gives a more reliable determination of the gluon distribution in the nucleon.
No description provided.
HERE THE QBAR IS D2(SIG(ANU))/DX/DY - (1-Y)**2*D2(SIG(NU))/DX/DY.
Using the data on deep inelastic muon scattering on iron and deuterium the ratio of the nucleon structure functions F 2 N ( Fe )/ F 2 N ( D ) is presented. The observed x -dependence of this ratio is in disagreement with existing theoretical predictions.
RANGE OF Q*2 VARIES WITH X. E.G. AT X=0.05 , 9<Q2<27. AT X=0.65 , 36<Q2<170 GEV**2.
Results on moments of the azimuthal angle ϕ of final state hadrons from 120 GeV and 280 GeV μp scattering are presented. A ϕ asymmetry is observed and its W 2 , Q 2 , z and p T dependences compared with model calculations which include intrinsic transverse momentum and first order QCD corrections. These studies indicate that the observed asymmetry is mainly due to intrinsic transverse momentum k T .
No description provided.
Typical phi distribution.
No description provided.
Measurements are presented of the variation with Q 2 (scaling violation) of the hadron multiplicity in deep inelastic muon-proton scattering. An increase in the average multiplicity of both the charged hadrons and K 0 mesons is observed with increasing Q 2 or x Bj for fixed centre-of-mass energy W . The study of the shape of the effective fragmentation function D h ( z , W , Q 2 ) shows that the increase of the particle yield with Q 2 takes place for low z particles. The variation of the hadron distributions with Q 2 is also studied in the current fragmentation region where a decrease in multiplicity is observed. Such effects are expected from QCD.
No description provided.
No description provided.
New data is presented on the ratios of structure functions F 2 ( x , Q 2 ) measured in deep inelastic muon scattering with deuterium, nitrogen, and iron targets. The existence of nuclear effects at large Q 2 is confirmed with improved systematic accuracy. The ratio F 2 Fe ( x ) F 2 D 2 ( x ) covers the range 0.20 ⩽ x ⩽ 0.70 and is in agreement with earlier measurements. The ratio F 2 N 2 ( x )/ F 2 D 2 ( x ) is measured over the range 0.08 ⩽ x ⩽ 0.70 and is compatible with unity below x = 0.3.
VALUES OF Q2 CORRESPONDING TO THE X-BINS IN THIS TABLE ARE:- 46-106,46-106,53-150,53-200,70-200,80-200 RESPECTIVELY.
VALUES OF Q2 CORRESPONDING TO THE X-BINS IN THIS TABLE ARE:- 26-40,26-61,30-80,30-106,30-106,30-150,30-200,35-200,46-200.
The reactionγγ→3π+3π- has been studied usig the JADE detector at PETRA. The topological cross sectionσ(γγ→3π+3π-) was measured in the CM energy range 1.5–5.5 GeV. The production ofρ0,s was observed and the average number ofρ0,s per event measured. The contributions of the subprocessesγγ→ρ02π+2π-,γγ→ρ0ρ0π+2π- andγγ→ 3π+3π- (phase space) were studied and 95% C.L. upper limits for the cross sectionσ(γγ→ρ0ρ0π+π- determined. Finally the Bose-Einstein correlation for pairs of like signed pions was observed. A fit to a standard parametrization gave results consistent with other studies of this effect in pion systems.
Topological cross section.
Fractions of events for different final states resulting from the extended liklihood fit using incoherent weights.
Fractions of events for different final states resulting from the extended liklihood fit using coherent weights.