A search was made among ν μ charged current events collected in the NOMAD experiment for the reaction: ν μ +N→μ − +D ★+ + hadrons ↪ D 0 +π + ↪ K − +π + . A high purity D ★+ sample composed of 35 events was extracted. The D ★+ yield in ν μ charged current interactions was measured to be T =(0.79±0.17(stat.)±0.10(syst.))%. The mean fraction of the hadronic jet energy taken by the D ★+ is 0.67±0.02(stat.)±0.02(syst.). The distributions of the fragmentation variables z, P T 2 and x F for D ★+ are also presented.
Distribution in Feynman X.
Distribution in transverse momentum.
Distribution in fractional energy Z.
A study of strange particle production in muon neutrino charged current interactions has been performed using the data from the NOMAD experiment. Yields of neutral strange particles K0s, Lambda, AntiLambda have been measured. Mean multiplicities are reported as a function of the event kinematic variables Enu, W2 and Q2 as well as of the variables describing particle behaviour within a hadronic jet: xF, z and pT2. Decays of resonances and heavy hyperons with identified K0s and Lambda in the final state have been analyzed. Clear signals corresponding to K*+-, Sigma*+-, Xi- and Sigma0 have been observed.
Measured yields of the neutral strange particles measured in this analysis.The second line (marked *) is a recalculation taking into account contributions from both primary and secondary V0. The values for K0 are the K0S rates multipl ied by 2.
Measured yields as a function of E, the neutrino energy.
Measured yields as a function of W**2.
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.
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.
Characteristics of hadron production in diffractive deep-inelastic positron-proton scattering are studied using data collected in 1994 by the H1 experiment at HERA. The following distributions are measured in the centre-of-mass frame of the photon dissociation system: the hadronic energy flow, the Feynman-x (x_F) variable for charged particles, the squared transverse momentum of charged particles (p_T^{*2}), and the mean p_T^{*2} as a function of x_F. These distributions are compared with results in the gamma^* p centre-of-mass frame from inclusive deep-inelastic scattering in the fixed-target experiment EMC, and also with the predictions of several Monte Carlo calculations. The data are consistent with a picture in which the partonic structure of the diffractive exchange is dominated at low Q^2 by hard gluons.
Energy flow distributions in the gamma*-pomeron CM frame.. Positive etarap corresponds to the direction of the incoming photon.
Energy flow distributions in the gamma*-pomeron CM frame.. Positive etarap corresponds to the direction of the incoming photon.
Energy flow distributions in the gamma*-pomeron CM frame.. Positive etarap corresponds to the direction of the incoming photon.
We have studied the production of J/ ψ , ψ ′ and prompt muon pairs in the mass continuum from a sample of sulfur-uranium interactions at 200 GeV/c per nucleon. We report, in this letter, results obtained for the transverse momentum distributions and their dependence on the transverse energy released in the collision, used as an estimator of the centrality of the nucleus-nucleus interaction.
No description provided.
No description provided.
No description provided.
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.
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.
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.
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.
The scale dependence of the evolution of photoproduction cross sections with the photon-proton centre of mass energy W is studied using low Q~2 < 0.01 GeV~2 e~+p interactions collected by the H1 experiment at HERA. The value of the largest transverse momentum of a charged particle in the photon fragmentation region is used to define the hard scale. The slope of the $W$ dependence of the cross section is observed to increase steeply with increasing transverse momentum. The result is compared to measurements of the Q~2 evolution of the W dependence of the virtual photon-proton cross section. Interpretations in terms of QCD and in terms of Regge phenomenology are discussed.
The gamma p cross section is parameterized as CONST*(W**2)**POWER.
Measurements are presented of $K~0$ meson and $\Lambda$ baryon production in deep-inelastic positron-proton scattering (DIS) in the kinematic range $10 < Q~2 < 70\,$GeV$~2$ and $10~{-4} < x < 10~{-2}$. The measurements, obtained using the H1 detector at the HERA collider, are discussed in the light of possible mechanisms for increased strangeness production at low Bjorken-$x$. Comparisons of the $x_F$ spectra, where $x_F$ is the fractional longitudinal momentum in the hadronic centre-of-mass frame, with results from electron-positron annihilation are made. The $x_F$ spectra and the $K~0$ ``seagull'' plot are compared with previous DIS results. The mean $K~0$ and $\Lambda$ multiplicities are studied as a function of the centre-of-mass energy $W$ and are observed to be consistent with a logarithmic increase with $W$ when compared with previous measurements. A comparison of the levels of strangeness production in diffractive and non-diffractive DIS is made. An upper limit of $0.9\,$nb, at the $95\%$ confidence level, is placed on the cross-section for QCD instanton induced events.
The XL distribution for K0 particles.
The XL distribution for LAMBDA particles.
Corrected Mean PT**2 for K0 production RE = E+ P --> E+ K0 X.
A measurement of inclusive charged particle distributions in deep inelastic $ep$ scattering for $\gamma~* p$ centre-of-mass energies $75< W < 175$GeV and momentum transfer squared $10< Q~2 < 160$GeV$~2$ from the ZEUS detector at HERA is presented. The differential charged particle rates in the $\gamma~* p$ centre-of-mass system as a function of the scaled longitudinal momentum, $x_F$, and of the transverse momentum, $p_t~*$ and $<\!\!p_t~{*\,2}\!\!>\,\,$ , as a function of $x_F$, $W$ and $Q~2$ are given. Separate distributions are shown for events with (LRG) and without (NRG) a rapidity gap with respect to the proton direction. The data are compared with results from experiments at lower beam energies, with the naive quark parton model and with parton models including perturbative QCD corrections. The comparison shows the importance of the higher order QCD processes. Significant differences of the inclusive charged particle rates between NRG and LRG events at the same $W$ are observed. The value of $<\!\!p_t~{*\,2}\!\!>\,\,$ for LRG events with a hadronic mass $M_X$, which excludes the forward produced baryonic system, is similar to the $<\!\!p_t~{*\,2}\!\!>\,\,$ value observed in fixed target experiments at $W \approx M_X$.
Differential multiplicites for NRG events.. XL is parallel to the virtual photon axis.
Differential multiplicites for NRG events.. PT is relative to the virtual photon axis.
Mean PT**2 for NRG events.. PT is relative to the virtual photon axis.
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