Properties of hadronic final states in diffractive deep inelastic e p scattering at HERA.

The ZEUS collaboration Chekanov, S. ; Derrick, M. ; Krakauer, D. ; et al.
Phys.Rev.D 65 (2002) 052001, 2002.
Inspire Record 560352 DOI 10.17182/hepdata.46869

Characteristics of the hadronic final state of diffractive deep inelastic scattering events, ep -> eXp, were studied in the kinematic range 4 < M_X < 35 GeV, 4 < Q^2 < 150 GeV^2, 70 < W < 250 GeV and 0.0003 < x_pom < 0.03 with the ZEUS detector at HERA using an integrated luminosity of 13.8 pb^{-1}. The events were tagged by identifying the diffractively scattered proton using the leading proton spectrometer. The properties of the hadronic final state, X, were studied in its center-of-mass frame using thrust, thrust angle, sphericity, energy flow, transverse energy flow and ``seagull'' distributions. As the invariant mass of the system increases, the final state becomes more collimated, more aligned and more asymmetric in the average transverse momentum with respect to the direction of the virtual photon. Comparisons of the properties of the hadronic final state with predictions from various Monte Carlo model generators suggest that the final state is dominated by qqg states at the parton level.

16 data tables

Thrust distribution for a DIS hadronic final state mass between 11 and 17.8GeV.

Thrust distribution for a DIS hadronic final state mass between 17.8 and 27.7 GeV.

Sphericity distribution for a DIS hadronic final state mass between 11 and 17.8 GeV.

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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

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.

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.

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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Inclusive single-particle distributions and transverse momenta of forward produced charged hadrons in mu p scattering at 470-GeV

The E665 collaboration Adams, M.R. ; Aderholz, M. ; Aid, S. ; et al.
Z.Phys.C 76 (1997) 441-463, 1997.
Inspire Record 450187 DOI 10.17182/hepdata.37889

Using data from the Fermilab fixed target experiment E665, general properties of forward produced charged hadrons in μp interactions at a primary muon energy of 470 GeV are investigated. The normalized inclusive singleparticle distributions for Feynman-x D(xF ) and for the transverse momentum D(p2t , xF ) are measured as a function of W and Q2. The dependence of the average transverse momentum squared 〈p2t〉 on xF , W and Q2 is studied. The increasing contribution from diffractive production as Q2 decreases leads to a reduction of the average charged hadron multiplicities at low (positive) xF and an enhancement at large xF , for Q2 ≲ 10 GeV2. It also reduces 〈p2t〉 for Q2 ≲ 5 GeV2 and 0.4 ≲ xF < 1.0.

35 data tables

Normalised inclusive single particle distributions of charged hadrons for all events in W intervals. Additional systematic uncertainty of 4 PCT.

Normalised inclusive single particle distributions of charged hadrons for all events in Q**2 intervals. Additional systematic uncertainty of 4 PCT.

Normalised inclusive single particle distributions of charged hadrons for all events in X (Bjorken) intervals. Additional systematic uncertainty of 4 PCT.

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Production of neutral strange particles in muon - nucleon scattering at 490-GeV

The E665 collaboration Adams, M.R. ; Aderholz, M. ; Aïd, S. ; et al.
Z.Phys.C 61 (1994) 539-550, 1994.
Inspire Record 362429 DOI 10.17182/hepdata.42473

The production ofK0, Λ and\(\bar \Lambda \) particles is studied in the E665 muon-nucleon experiment at Fermilab. The average multiplicities and squared transverse momenta are measured as a function ofxF andW2. Most features of the data can be well described by the Lund model. Within this model, the data on the K0/π± ratios and on the averageK0 multiplicity in the forward region favor a strangeness suppression factors/u in the fragmentation process near 0.20. Clear evidence for QCD effects is seen in the average squared transverse momentum ofK0 and Λ particles.

10 data tables

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