Inclusive ϱ 0 and φ production is investigated in K + p interactions at 32 GeV/ c . Total and semi-inclusive ϱ 0 and φ cross sections, longitudinal and transverse momentum distributions, including 〈 P T versus x dependence are presented. No evidence for a sea-gull effect is observed. Comparison with quark models strongly suggests the possibility that a large fraction of the ϱ 0 and vector mesons are produced as fragmentation products of the incident particles. Study of uncorrelated π + π − pairs in the ϱ 0 mass range provides possible indirect evidence for the existence of diquarks in the proton.
No description provided.
No description provided.
No description provided.
None
No description provided.
No description provided.
No description provided.
None
No description provided.
No description provided.
No description provided.
Results are presented on total and semiinclusive cross sections, longitudinal and transverse momentum distributions of the tensor mesonsK*+(1430),K*0(1430), andf(1270) observed inK+p interactions at 32 GeV/c. The data are compared withK*+(892).K*0(896) and ϱ0 vector meson production in the same experiment. The shapes of inclusive invariantx-spectra for the strange vector and tensor mesons are found to be rather similar, after removal of diffractive and quasi-two-body channels, in agreement with quark-recombination ideas.
MULT FOR THE TENSOR MESONS CALCULATED AS MULT=SIG(RES)/SIG(N<=8), WHERE SIG(N<=8) IS THE SUM OF TOPOLOGICAL CROSS SECTIONS WITH N <= 8.
No description provided.
No description provided.
The jet character of the hadronic final states produced ine+e− annihilations is studied in terms of jet measures such as thrust, sphericity, jet opening angle and jet masses, in the energy range 7.7 to 31.6 GeV. All distributions and averages have been corrected for detector effects and initial state radiation. The energy dependence of the averages of these jet quantities is used to estimate the contributions due to perturbative QCD and fragmentation effects. Correlations between the jet measures and the multiplicity of charged hadrons are also presented.
DIFFERENTIAL THRUST DISTRIBUTIONS WHERE THRUST IS MAX(SUM(ABS(PLONG))/SUM(ABS(P))).
MEAN THRUST VALUES AS A FUNCTION OF CM ENERGY.
DIFFERENTIAL SPERICITY DISTRIBUTIONS WHERE SPHERICITY IS 3/2*MIN(SUM(PT**2)/SUM(ABS(P))).
We have measured the electron, muon, and charged-hadron pair production rates in two-phonon interactions for invariant masses above 2.0 GeV over a large of momentum transfer. The cross sections for electron and muon pairs show good agreement with the QED predictions at both small and large momentum transfer. The observed rate of hadron production is less than 6% of the rate that QED predicts for point-like hadrons, consistent with recent leading-order QCD calculations.
LOW Q**2 CROSS SECTIONS.
DIFFERENTIAL CROSS SECTIONS IN THE INVARIANT MASS FOR MUON AND ELECTRON PAIRS IN THE UNTAGGED, LOW Q**2 REGION.
HIGH Q**2 CROSS SECTIONS.
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.
We present an analysis of theKs0Ks0 system produced in the reaction π−p→Ks0Ks0n at 63 GeV based on ∼700 events in the kinematical region of |t|<0.5 GeV2. We concentrate on masses between 1,200 and 1,600 MeV where a double maximum structure is observed. Performing an amplitude analysis in this mass interval we find thatS,D0 andD+ waves contribute to the mass spectrum at approximately equal strength. The peaks are attributed to spin 2 waves. However, we failed to explained them by interferingf(1270),A2(1310) andf′(1520) resonances alone. While the first peak can be associated withf(1270)−A2(1310) production, an additional tensor meson is needed with mass of ∼1410 MeV and a narrow width for a description of the second one. The analysis as well as the energy dependence deduced from some publishedKs0Ks0 mass spectra suggests this object to be dominantly produced by a natural parity exchange. Because the 2++\(q\bar q\) nonet is already complete the nature of the new tensor meson is an open question.
No description provided.
We observe γγ → η′ production in the reaction e + e − → e + e − π + π − γ. We measure the product γ γγ ( η ′) B ( η ′ → ϱ 0 γ ) to be 1.14 ± 0.08 ± 0.11 keV. A first measurement of the γγ → η′ transition form factor is made for Q 2 up to 1 GeV 2 .
No description provided.
We have measured the reaction γγ → π + π − π 0 using the PLUTO detector at PETRA. A pronounced enhancement is seen in the π + π − π 0 mass distribution corresponding to the A 2 meson. The event configuration in this enhancement favors a 2 + spin-parity assignment. The value of Γ γγ =1.06 ±0.18±0.19 keV obtained for the two-photon decay width of the A 2 agrees with previous measurements and with quark model predictions.
No description provided.
Forum