A study has been made of pseudoscalar mesons produced centrally in pp interactions. The results show that the eta and etaprime appear to have a similar production mechanism which differs from that of the pi0. The production properties of the eta and etaprime are not consistent with what is expected from double Pomeron exchange. In addition the production mechanism for the eta and etaprime is such that the production cross section are greatest when the azimuthal angle between the pT vectors of the two protons is 90 degrees.
No description provided.
Resonance production as a function of dPT - the difference in the transverse momentum vectors of the two exchange particles, expressed as a percentage of its total contribution.
T distributions have been fitted to the form D(SIG)/D(T) = const(NAME=ALPHA)*EXP(-SLOPE(C=1)*T) + const(NAME=BETA)*T**2*EXP(-SLOPE(C=2)*T).
A search for centrally produced charmonium states has been presented. There is no significant evidence for any charmonium production. An upper limit of 2 nb is found for the cross section of chic production using the decay chic(1P)-> J/psi gamma.
The reaction pp -> pf (pi+pi-pi0) ps has been studied at 450 GeV/c in an experiment designed to search for gluonic states. A spin analysis has been performed and the dPT filter applied. The analysis confirms the previous observation that all undisputed qqbar states are suppressed at small dPT. In addition, a clear difference is observed in the production mechanism for the eta and omega.
SIG(C=TOT) denotes the total cross section for each resonance. The variable ABS(PT(P=3)-PT(P=4)) is used as a glueball-QUARK QUARKBAR filter (see F.E.Close and A.Krik, PL 397B, 333 (1997)).
The reaction pp -> pf (pi+pi-pi+pi-) ps has been studied at 450 GeV/c in an experiment designed to search for gluonic states. A spin analysis has been performed and the dPT filter applied. In addition to the well known f1(1285) there is evidence for two JPC=2-+ states called the eta2(1620) and eta2(1875) and a broad scalar called the f0(2000). The production of these states as a function of the dPT kinematical filter shows the behaviour expected for qqbar states. In contrast, there is evidence for two states at 1.45 GeV and at 1.9 GeV which do not show the behaviour observed for qqbar states.
SIG(C=TOT) denotes the total cross section for each resonance.
A study of the reactions pp -> pfps(K+K-pi+pi-) and pp -> pfps(K+K-pi+pi-pi0) shows evidence for the K*K* and phi omega channels respectively. The K*K* mass spectrum shows a broad distribution with a maximum near threshold and an angular analysis shows that it is compatible with having JP = 2+. The behaviour of the cross-section as a function of centre of mass energy, and the four momentum transfer dependence, are compatible with what would be expected if the K*K* system was produced via double Pomeron exchange. The dPT behaviour of the phi omega channel is similar to what has been observed for all the undisputed qqbar states. In contrast, the dPT behaviour of the K*K* final state is similar to what has been observed for the phi phi final state and for previously observed glueball candidates.
Corrections for geometrical acceptances, detector efficiencies, losses due to cuts, charged kaon decay and unseen decay modes were applied.
The variable ABS(PT(P=3)-PT(P=4)) is used as a glueball-QUARK QUARKBAR filter (see F.E.Close and A.Krik, PL 397B, 333 (1997)). SIG(C=TOT) stands for the cross section for the whole ABS(PT(P=3)-PT(P=4))interval.
Results are presented of an analysis of the reactions pp -> pf(k0k+pi-)ps and pp -> pf(K0K0pi0)ps at 450 GeV/c. Clear f1(1285) and f1(1420) signals are seen and a spin parity analysis shows that both have IG JPC=0+ 1++. The f1(1285) decays to a0(980)pi and the f1(1420) decays to K* Kbar. Both states have a similar dependence as a function of dPT consistent with what has been observed for other qqbar states. Evidence is also presented for a K*Kbar decay mode of the eta2(1620).
SIG(C=TOT) denotes the total cross section for each resonance.
A partial wave analysis of the centrally produced eta pi0 and eta pi- channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. Clear a0(980) and a2(1320) signals have been observed in S and D+ waves respectively. The dPT, phi and |t| distributions of these resonances are presented.
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No description provided.
No description provided.
Measurements of the cross section for the reaction p+p→π0+anything have been completed. The data cover a range of incident proton energies 50-400 GeV, π0 transverse momenta 0.3-4 GeV/c, and laboratory angles 30-275 mrad. The experiment was performed using the internal proton beam at the Fermi National Accelerator Laboratory. A lead-glass counter was used to detect photons from the decay of π0's produced by collisions in thin targets of hydrogen or carbon. Tables of the measured cross sections are presented.
No description provided.
We have measured the differential production cross sections as a function of scaled momentum x_p=2p/E_cm of the identified hadron species pi+, K+, K0, K*0, phi, p, Lambda0, and of the corresponding antihadron species in inclusive hadronic Z0 decays, as well as separately for Z0 decays into light (u, d, s), c and b flavors. Clear flavor dependences are observed, consistent with expectations based upon previously measured production and decay properties of heavy hadrons. These results were used to test the QCD predictions of Gribov and Lipatov, the predictions of QCD in the Modified Leading Logarithm Approximation with the ansatz of Local Parton-Hadron Duality, and the predictions of three fragmentation models. Ratios of production of different hadron species were also measured as a function of x_p and were used to study the suppression of strange meson, strange and non-strange baryon, and vector meson production in the jet fragmentation process. The light-flavor results provide improved tests of the above predictions, as they remove the contribution of heavy hadron production and decay from that of the rest of the fragmentation process. In addition we have compared hadron and antihadron production as a function of x_p in light quark (as opposed to antiquark) jets. Differences are observed at high x_p, providing direct evidence that higher-momentum hadrons are more likely to contain a primary quark or antiquark. The differences for pseudoscalar and vector kaons provide new measurements of strangeness suppression for high-x_p fragmentation products.
Charged kaon fraction and differential cross section per hadron Z0 decay. The last line in the table is the integral over the full X range of the measurement.. There is an additional 1.7 PCT normalization error (included in the integral).
The K0 + K0BAR inclusive differential cross section. The last line in the table is the integral over the full X range of the measurement.. There is an additional 3.4 PCT normalization error (included in the integral).
The LAMBDA + LAMBDABAR inclusive differential cross section. The last line in the table is the integral over the full X range of the measurement.. There is an additional 3.4 PCT normalization error (included in the integral).
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