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.
Charm D-meson production in 360 GeV pp interactions has been studied using the high-resolution hydrogen bubble chamber LEBC and the European Hybrid Spectrometer. D-mesons are produced with a differential cross section of the form d 2 σ d x d p T 2 δ(1-x) n exp (-ap T 2 ) , with n =1.8± 0.8 and a =1.1±0.03 GeV/ c −2 for the Feynman x and Transverse momentum p T behaviour. The inclusive partle prticle crossssection for D and D̄;measured to be: σ(D/ D ̄ ) = (56 −12 25 μ b (for all x ). The Λ c D ̄ cross section can be estimated to be ≈20 μ b. No strong correlation is observed between DD̄ pairs. The results are compared with results from a study of D-meaon production in 360 GeV/ c π − p interactions also using LEBC-EHS.
No description provided.
We have measured the production of one and two large transverse momentum hadrons in p p and pp interactions in the range 2 < p T < 6 GeV/ c for the central rapidity region |y| < 0.9 at s = 63 and 31 GeV . No statistically significant difference between p p and pp collisions is observed. The results are in accordance with lowest order QCS perturbative calculations and rule out a large contribution of Constituent Interchange Model (CIM), di-quark of quark-fusion subprocesses in this kinematic range.
No description provided.
No description provided.
Results on charged particle production in pp̄ collision at s 1 2 = 540 GeV are presented. The data were obtained at the CERN pp̄ collider using the UA1 detector, operated without magnetic field. The central particle density is 3.3 + - 0.2 per unit o pseudo-rapidity for non-diffractive events. KNO scaling of the multiplicity distributions withresults from ISR energies is observed.
Pseudorapidity density distribution for all charged multiplicities corrected for acceptance and backgrounds by excluding NSD events. Data have been read from the plot.
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Inclusive ϕ-meson production has been measured for 100 GeV/cK−,\(\bar p\) andp incident on a Be target. Differential cross sectionsdσ/dxF anddσ/dp⊥2 are presented in the interval 0.075<xF<0.225 and 0<p⊥<1 GeV/c respectively. The shape of thedσ/dxF distributions agrees with predictions from a quark fusion model. Comparison with cross sections measured on a hydrogen target in the samexF andp⊥ range suggest a linearA-dependence fromA=1 toA=9.
No description provided.
With a PETRA energy scan in ≤30-MeV steps, the continuum production of open top quark up to 38.54 GeV is excluded. Over regions of energy scan from 29.90 to 38.63 GeV limits are set on the product of hadronic branching ratio and electronic width BhΓee for toponium to be less than 2.0 keV at the 95% confidence level. By a search for flavor-changing neutral currents in b decay, models without a top quark are excluded.
MEASUREMENT OF R IN ENERGY SCAN FROM SQRT(S) = 29.9 TO 3.146 AND 33.0 TO 36.72.
MEASUREMENT OF R IN THE RANGE SQRT(S) 37 TO 38.63 GEV.
THRUST DISTRIBUTION FOR EVENTS IN THE RANGE SQRT(S) 37.94 TO 38.63 AND 38.54 TO 38.63.
The reaction π−N→KS0KS0π−N′ at 200 GeV/c has been observed with a sensitivity of 450±150 events/μb. The KS0KS0π− system exhibits substantial K*−(890)K0 production. Also produced are f0(1270)π−, f′(1515)π−, and K*−(1430)K0 final states. These resonances occur predominantly at threshold. The diffractive KS0KS0π− cross section is 3.4±1.1 μb. An enhancement near the A3−(1680) is observed in the KS0KS0π− invariant-mass distribution.
No description provided.
EVIDENCE FOR A3 MESON SEEN.
Differential cross sections and polarisations in the reaction π + p→K + Σ + have been measured using the Rutherford Multiparticle Spectrometer at NIMROD. Data are presented at 26 momentum points at approximately 50 MeV/ c intervals in the range 1.282 to 2.473 GeV/ c with an order of magnitude more events than previous experiments. Legendre polynomial expansion coefficients have also been determined.
ERRORS HAVE SYSTEMATIC AND STATISTICAL ERRORS FOLDED IN QUADRATURE. TYPICAL STATISTICAL ERRORS ARE 2 PCT OR LESS.
No description provided.
No description provided.
We have observed exclusive production of K + K − and K S O K S O pairs and the excitation of the f′(1515) tensor meson in photon-photon collisions. Assuming the f′ to be production in a helicity 2 state, we determine Λ( f ′ → γγ) B( f ′ → K K ) = 0.11 ± 0.02 ± 0.04 keV . The non-strange quark of the f′ is found to be less than 3% (95% CL). For the θ(1640) we derive an upper limit for the product Λ(θ rarr; γγ K K ) < 0.03 keV (95% CL ) .
Data read from graph.. Errors are the square roots of the number of events.
Data read from graph.. Errors are the square roots of the number of events.
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