Two photon final states in e + e − annihilation have been analyzed at CM energies around 34 GeV. Good agreement with QED is observed. Lower limits for the QED cutoff parameters of Λ + > 59 GeV and Λ - > 44 GeV are determined. A search for two photons with missing energy yields an upper limit for the production of neutral particles which decay into a photon and a non-interacting particle. Constraints on the mass and the coupling strength of supersymmetric photinos are discussed.
Cross section for ABS(cos(theta)) <0.85.
No description provided.
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.
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.
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We use low mass dimuons (0.35 < M μμ ⩽ 2 GeV/ c 2 ) to analyse the production at high transverse momentum ( P T ⩾ 2 GeV/ c ) of the resonances ϱ, ω, π. We have studied the variation of the cross section with the type of incident particle (π, K, p) at 150, 200, 280 GeV/ c and the nuclear effects by comparison of platinum and hydrogen targets. There is no significant difference between the slopes of the transverse momentum distributions with those observed at lower P T (0 < P T < 2 GeV/ c ), meanwhile x F -distributions show a leading effect in the production of gf by kaons at these relatively high transverse momenta.
No description provided.
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None
1.0 cm WT target.
1.0 cm C target.
1.0 cm CU target.
The inclusive production of π± andK± mesons and of protons and antiprotons ine+e− annihilation has been measured at c.m. energies ofW=14, 22 and 34GeV. Using time of flight measurements and Cerenkov counters the full momentum range has been covered. Differential cross sections and total particle yields are given. At particle momenta of 0.4 GeV/c more than 90% of the charged hadrons are pions. With increasing momentum the fraction of pions among the charged hadrons decreases. AtW=34 GeV and a momentum of 5 GeV/c the particle fractions are approximately π±:K±:p,\(\bar p = 0.55:0.3:0.15\). On average an event atW=34 GeV contains 10.3±0.4π±, 2.0±0.2K± and 0.8±0.1p,\(\bar p\). In addition, we present results on baryon correlations using a sample of events where two or more protons and/or antiprotons are observed in the final state.
No description provided.
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We present data obtained from a 1.7 sr hadron calorimeter, triggered on transverse energy, in pp collisions at s =63 GeV at the CERN-ISR. From the change in the distribution of energy in the calorimeter, we extract the cross section for two-constituent hard scattering for p T between 6 and 14 GeV at y = 0. The decrease of this jet cross section over this p T range is consistent with exp (− bp T ), with b = (1.02 ± 0.09) GeV −1 . The slope and normalization of the cross section agree well with a QCD motivated Monte Carlo model. The ratio between jet and single particle cross sections [ dσ JET / dp T )/( dσ π 0 / dp T )]| y = 0 changes from about 200 at 6 GeV to about 1500 at 14 GeV.
No description provided.
No description provided.
The distribution of total tranverse energy ΣE T over the pseudorapidity interval −1 < η < 1 and an azimuthal range Δφ =300° has been measured in the UA2 experiment at the CERN p p collider ( s = 540 GeV ) using a highly segmented total absorption caloriter. In the events with very large ΣE T (ΣE T ⪆60 GeV ) most of the transverse energy is found to be contained in small angular regions as expected for high transverse momentum hadron jets. We discuss the properties of a sample of two-jet events with invariant two-jet masses up to 140 GeV c 2 and we measure the cross section for inclusive jet production in the range of jet transverse momenta between 15 and 60 GeV c .
No description provided.
HERE ET IS ACTUALLY THE ENERGY-DENSITY=ET/DELTA OMEGA.
No description provided.
Differential cross sections fore+e−→e+e−, τ+, τ- measured with the CELLO detector at\(\left\langle {\sqrt s } \right\rangle= 34.2GeV\) have been analyzed for electroweak contributions. Vector and axial vector coupling constants were obtained in a simultaneous fit to the three differential cross sections assuming a universal weak interaction for the charged leptons. The results,v2=−0.12±0.33 anda2=1.22±0.47, are in good agreement with predictions from the standardSU(2)×U(1) model for\(\sin ^2 \theta _w= 0.228\). Combining this result with neutrino-electron scattering data gives a unique axial vector dominated solution for the leptonic weak couplings. Assuming the validity of the standard model, a value of\(\sin ^2 \theta _w= 0.21_{ - 0.09}^{ + 0.14}\) is obtained for the electroweak mixing angle. Additional vector currents are not observed (C<0.031 is obtained at the 95% C.L.).
No description provided.
Combined MU and TAU asymmetry. See PL 114B(1982)282 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1234> RED = 1234 </a>) and ZP C14(1982)283 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1245> RED = 1245 </a>) for individual asymmetry measurements.
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.
Forum