HEPData Search

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Observation and Study of a Narrow State in a $\Sigma^-$ (1385) $K^+$ System

The Berlin-Budapest-Dubna-Moscow-Prague-Sofiya-Tbilisi collaboration Aleev, A.N. ; Arefev, V.A. ; Balandin, V.P. ; et al.

Z.Phys.C 25 (1984) 205, 1984.

Inspire Record 201523 DOI 10.17182/hepdata.39601

New data on the observation and study of a narrow resonance decaying intoΣ−(1,385)K+ have been obtained. The mass of the resonance is (1,956−6+8) MeV/c2, and its width is (27±15) MeV/c2. The resonance is produced in the diffraction dissociation of neutrons on quasi-free nucleons of carbon nuclei. The slope parameter of the differential cross section inPT2 is (9.9±3.0) (GeV/c)−2. The cross section times the branching ratio is (0.22±0.04) μb per nucleon. The resonance has one of the natural spinparities: 5/2+, 7/2− and so on.

5 data tables

Table 1

YN IS IN ARBITRARY UNITS.

Table 2

Table 3

ARBITRARY UNITS FOR YN.

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Measurements of inelastic J/psi and psi' photoproduction at HERA.

The ZEUS collaboration Chekanov, S. ; Krakauer, D. ; Magill, S. ; et al.

Eur.Phys.J.C 27 (2003) 173-188, 2003.

Inspire Record 601166 DOI 10.17182/hepdata.46546

The cross sections for inelastic photoproduction of J/psi and psi' mesons have been measured in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 38.0 pb-1. The events were required to have 0.1 < z < 0.9 and 50 < W < 180 GeV, where z is the fraction of the incident photon energy carried by the J/psi in the proton rest frame and W is the photon-proton centre-of-mass energy. The psi' to J/psi cross-section ratio was measured in the range 0.55 < z < 0.9. The J/psi data, for various ranges of transverse momentum, are compared to theoretical models incorporating colour-singlet and colour-octet matrix elements. Predictions of a next-to-leading-order colour-singlet model give a good description of the data, although there is a large normalisation uncertainty. The J/psi helicity distribution for z > 0.4 is compared to leading-order QCD predictions.

10 data tables

Table 1

Measurment of the total cross section, with various PT thresholds, in the high Z > 0.9 region.

Table 2

Ratio of cross section for PSI(2S) to J/PSI production. as a function of PT. Statistical errors only.

Table 3

Ratio of cross section for PSI(2S) to J/PSI production. as a function of W. Statistical errors only.

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rivet Analysis
A study of parton fragmentation in hadronic Z0 decays using Lambda Antilambda correlations.

The OPAL collaboration Abbiendi, G. ; Ackerstaff, K. ; Alexander, G. ; et al.

Eur.Phys.J.C 13 (2000) 185-195, 2000.

Inspire Record 474010 DOI 10.17182/hepdata.49312

The correlated production of Lambda and Lambdabar baryons has been studied using 4.3 million multihadronic Zo decays recorded with the OPAL detector at LEP. Di-lambda pairs were investigated in the full data sample and for the first time also in 2-jet and 3-jet events selected with the k_t algorithm. The distributions of rapidity differences from correlated Lambda-Lambdabar pairs exhibit short-range, local correlations and prove to be a sensitive tool to test models, particularly for 2-jet events. The JETSET model describes the data best but some extra parameter tuning is needed to improve agreement with the experimental results in the rates and the rapidity spectra simultaneously. The recently developed modification of JETSET, the MOdified Popcorn Scenarium (MOPS), and also HERWIG do not give satisfactory results. This study of di-lambda production in 2- and 3-jet events supports the short-range compensation of quantum numbers.

5 data tables

Table 1

Average multipicity of LAMBDA pairs in hadronic events.

Table 2

Average multipicity of LAMBDA pairs in 2-Jet events.

Table 3

Average multipicity of LAMBDA pairs in 3-Jet events.

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Event shape analysis of deep inelastic scattering events with a large rapidity gap at HERA.

The ZEUS collaboration Breitweg, J. ; Derrick, M. ; Krakauer, D. ; et al.

Phys.Lett.B 421 (1998) 368-384, 1998.

Inspire Record 450130 DOI 10.17182/hepdata.44419

A global event shape analysis of the multihadronic final states observed in neutral current deep inelastic scattering events with a large rapidity gap with respect to the proton direction is presented. The analysis is performed in the range $5 \leq Q^2 \leq 185\gev^2$ and $160 \leq W \leq 250\gev$, where $Q^2$ is the virtuality of the photon and $W$ is the virtual-photon proton centre of mass energy. Particular emphasis is placed on the dependence of the shape variables, measured in the $\gamma^*-$pomeron rest frame, on the mass of the hadronic final state, $M_X$. With increasing $M_X$ the multihadronic final state becomes more collimated and planar. The experimental results are compared with several models which attempt to describe diffractive events. The broadening effects exhibited by the data require in these models a significant gluon component of the pomeron.

21 data tables

Table 1

Measured (uncorrected) polar distribution of the sphericity axis w.r.t. thevirtual photon direction in the (gamma*-pomeron)rest frame Data are in bins of the mass of the final state hadronic system.

Table 2

Measured (uncorrected) polar distribution of the sphericity axis w.r.t. thevirtual photon direction in the (gamma*-pomeron)rest frame Data are in bins of the mass of the final state hadronic system.

Table 3

Measured (uncorrected) polar distribution of the sphericity axis w.r.t. thevirtual photon direction in the (gamma*-pomeron)rest frame Data are in bins of the mass of the final state hadronic system.

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Measurement of elastic J / psi photoproduction at HERA

The ZEUS collaboration Breitweg, J. ; Derrick, M. ; Krakauer, D. ; et al.

Z.Phys.C 75 (1997) 215-228, 1997.

Inspire Record 442537 DOI 10.17182/hepdata.44626

The reaction gamma p -> J/Psi p has been studied in ep interactions using the ZEUS detector at HERA. The cross section for elastic J/Psi photoproduction has been measured as a function of the photon-proton centre of mass energy W in the range 40 < W < 140 GeV at a median photon virtuality Q^2 of 5*10^{-5} GeV^2. The photoproduction cross section, sigma_{gamma p -> J/Psi p}, is observed to rise steeply with W. A fit to the data presented in this paper to determine the parameter $\delta$ in the form sigma_{gamma p -> J/Psi p} \propto W^{\delta} yields the value \delta = 0.92 \pm 0.14 \pm 0.10. The differential cross section dsigma/d|t| is presented over the range |t| < 1.0 GeV^2 where t is the square of the four-momentum exchanged at the proton vertex. d\sigma/d|t| falls exponentially with a slope parameter of 4.6 \pm 0.4 (+0.4-0.6) GeV^{-2}. The measured decay angular distributions are consistent with s-channel helicity conservation.

9 data tables

Table 1

Data from the electron channel. Second systematic error is that attributed to the uncertainty in the modelof proton dissociation used for background subtraction.

Table 2

Data from the muon channel. Second systematic error is that attributed to the uncertainty in the modelof proton dissociation used for background subtraction.

Table 3

Data from the electron channel. Second systematic error is that attributed to the uncertainty in the modelof proton dissociation used for background subtraction.