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.
The electroproduction of rho mesons with proton diffractive dissociation for Q^2 > 7 GeV^2 and the elastic electroproduction of Phi mesons for Q^2 > 6 Gev^2 are studied in e^+ p collisions at HERA with the H1 detector, for an integrated luminosity of 2.8 pb-1. The dependence of the cross sections on P_t^2 and Q^2 is measured, and the vector meson polarisation obtained. The cross section ratio between proton dissociative and elastic production of rho mesons is measured and discussed in the framework of the factorisation hypothesis of diffractive vertices. The ratio of the elastic cross section for Phi and rho meson production is investigated as a function of Q^2.
Corrected PT**2 distribution for RHO production from the proton dissociative sample. Statistical errors only.
Cross sections and ratio of proton dissociative to elastic cross sections.
Cross sections and ratio of proton dissociative to elastic cross sections.
The inclusive yield of photons has been measured from deep inelastic interactions of 200 GeV muons on hydrogen. After subtracting the contributions from hadron electromagnetic decays and Bethe-Heitler muon bremsstrahlung, residual photons are observed at low p T and low z at a mean level of 0.15±0.06 per interaction. The quark Compton scattering process is unable to explain the data, thus indicating an anomalous photon production.
Z distribution of anomalous direct photons.
PT distribution of anomalous direct photons.
The final states of charged hadrons produced in 280 GeV μp scattering are analysed with respect to their planarity and jet structure. Distributions of p ⊥ 2 in and p ⊥ out 2 are presented. A two jet structure in the forward hemisphere is observed for events with high p ⊥ tracks are predicted by QCD models.
PTIN**2 is the sum of the PTIN components squared.
PTOUT**2 is the sum of the PTOUT components squared.
We present an experimental study of jetproduction in photon-photon interactions for 0.1≲Q2≲120 GeV2 and jet transverse momentum,pT, up to 5 GeV/c. At alQ2, the data show a highpT, tail, characteristic of a point-like interaction. The jet production cross-section approaches the quarkparton model (QPM) expectation as either jetpT orQ2 increases. Overall, the data are well described in both total cross-section and event topology by the sum of a vector-dominance model and a point-like interaction, represented by the QPM.
No description provided.
We present new high statistics data on hadron production in photon-photon reactions. The data are analyzed in terms of an electron-photon scattering formalism. The dependence of the total cross section of Q 2 , the four-momentum transfer squared of the scattered electron, and on the mass W of the hadronic system is investigated. The data are compared to predictions from Vector-Meson Dominance and the quark model.
No description provided.
DEPENDENCE ON VISIBLE HADRONIC INVARIANT MASS.
Data read from graph.
New results on the forward produced protons and antiprotons in high energy muon-nucleon scattering are presented. Their W 2 , z and p 2 T dependences are compared with those of the other charged hadrons. Significant differences are observed which can be related to the flavour content of the target and to a difference between the baryon content of quark and gluon jets.
No description provided.
No description provided.
No description provided.
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