Search for baryon pairs production ine+e− annihilation at\(\sqrt s= 2386 MeV\) is reported. The data relate to a luminosity of 161 nb−1 collected by the DM2 experiment at DCI, the Orsay colliding ring. First measurements of directe+e− annihilation into\(\Lambda \bar \Lambda \) and ofe+e−→\(p\bar p\) at this energy are presented. First observation of a goode+e−→\(n\bar n\) candidate is reported and upper limits are given fore+e−→\(n\bar n, \Lambda \bar \sum ^0+ c.c.\) and\(\Sigma ^0 \bar \Sigma ^0 \).
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PT(P=3,NAME=OUT)**2 - MEAN SQUARE OF THE PROJECTION OF THE ASSOCIATED PARTICLE TRANSVERSE MOMENTUM ONTO THE NORMAL TO THE TRIGGER PARTICLE PRODUCTION PLANE.
We have measured the cross section for production of ψ and ψ′ in p¯ and π− interactions with Be, Cu, and W targets in experiment E537 at Fermilab. The measurements were performed at 125 GeV/c using a forward dimuon spectrometer in a closed geometry configuration. The gluon structure functions of the p¯ and π− have been extracted from the measured dσdxF spectra of the produced ψ's. From the p¯W data we obtain, for p¯, xG(x)=(2.15±0.7)[1−x](6.83±0.5)[1+(5.85±0.95)x]. In the π− case, we obtain, from the W and the Be data separately, xG(x)=(1.49±0.03)[1−x](1.98±0.06) (for π−W), xG(x)=(1.10±0.10)[1−x](1.20±0.20) (for π−Be).
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We present the charged-particle multiplicity distributions for e+e− annihilation at center-of-mass energies from 50 to 61.4 GeV. The results are based on a data sample corresponding to a total integrated luminosity of 30 pb−1 obtained with the AMY detector at the KEK storage ring TRISTAN. The charged-particle multiplicity distributions deviate significantly from the modified Poisson and pair Poisson distributions, but follow Koba-Nielsen-Olesen scaling and are well reproduced by the LUND parton-shower model.
Fully corrected charged particle multiplicity distributions. Errors for n=2 and 4 are systematic only since these were derived using the LUND 6.3 Monte Carlo normalized to the observations at higher n values.
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The reactionγγ→π+π−π+π− has been studied with the ARGUS detector. The rate in the invariant mass region below 1.8 GeV/c2 is found to be largely due toρ0ρ0 production. A spin-parity analysis shows a dominance of the partial wave (JP,Jz)=(2+, 2) with a small admixture fromJP=0+. The contribution of negative parity states is consistent with zero. The large ratio of cross sectionsσ(γγ→ρ0ρ0)/σ(γγ→ρ+ρ−)≃4, and the dominance of theJP=2+ wave in the reactionγγ→ρ0ρ0 is a signature consistent with the production of an exotic (I=2) resonance.
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Statistical errors only.. Cross-section assuming phase-space distribution, as obtained by a 7 parameter fit.
Statistical errors only.. Cross-section assuming phase-space distribution, as obtained by a 7 parameter fit.
Using the ARGUS detector at the e + e - storage ring DORIS II at DESY, we have observed the decay D s + → η'π + in two decay modes of the η'. We measure the ratio of branching ratios BR(D s + → η'π + )/BR(D s + → Øπ + ) to be 2.5±0.5±0.3.
The cross section times Br(D/S+ --> ETAPRIME PI+), but is not included the ETAPRIME branching ratio.
The reaction p p → Λ Σ 0 together with its charge conjugate channel (c.c.) has been measured at LEAR. The incident p momentum was 1.695 GeV/ c , corresponding to an excess energy above threshold of 14.8 MeV. Results are given for the production cross section and the differential cross section as well as for the polarization. Comparisons are made with theoretical calculations and with the reaction p p → Λ Λ .
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A measurement of the cross section for e + e - → hadrons using 11 000 hadronic decays of the Z boson at ten different center-of-mass energies is presented. A three-parameter fit gives the following values for the Z mass M z , the total width Γ z , the product of the electronic and hadronic partial widths Γ e Γ h , and the unfolded pole cross section σ 0 : M Z =91.171±0.030(stat)±0.030 (beam) GeV, Γ Z =2.511±0.065 GeV, Γ e Γ h =0.148±0.006 (stat.)±0.004 (syst.) GeV 2 , σ 0 =41.6±0.7(stat.)±1.1 (syst.) nb,
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Thick-target recoil properties of deep spallation and fragmentation products of the interaction of tantalum with 3.65 AGeV 12C-ions and 3.65 GeV protons have been studied. The kinematic parameters such as mean product kinetic energies and velocities of the remnant have been deduced from the data by means of the two-step vector velocity model of high-energy reactions. The results have also been used to test the applicability of the factorization hypothesis to the kinematic properties.
ASYM=F/B, WHERE F AND B ARE THE FRACTIONAL NUMBERS OF PRODUCT RECOILING INTO THE FORWARD AND BACKWARD CATCHER, RESPECTIVELY.
ASYM=F/B, WHERE F AND B ARE THE FRACTIONAL NUMBERS OF PRODUCT RECOILING INTO THE FORWARD AND BACKWARD CATCHER, RESPECTIVELY.
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ASYM=F/B, WHERE F AND B ARE THE FRACTIONAL NUMBERS OF PRODUCT RECOILING INTO THE FORWARD AND BACKWARD CATCHER, RESPECTIVELY.
ASYM=F/B, WHERE F AND B ARE THE FRACTIONAL NUMBERS OF PRODUCT RECOILING INTO THE FORWARD AND BACKWARD CATCHER, RESPECTIVELY.
ASYM=F/B, WHERE F AND B ARE THE FRACTIONAL NUMBERS OF PRODUCT RECOILING INTO THE FORWARD AND BACKWARD CATCHER, RESPECTIVELY.
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