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Thrust jet analysis of deep-inelastic large-rapidity-gap events.

The H1 collaboration Adloff, C. ; Aid, S. ; Anderson, M. ; et al.

Eur.Phys.J.C 1 (1998) 495-507, 1998.

Inspire Record 451036 DOI 10.17182/hepdata.44396

A thrust analysis of Large-Rapidity-Gap events in deep-inelastic ep collisions is presented, using data taken with the H1 detector at HERA in 1994. The average thrust of the final states X, which emerge from the dissociation of virtual photons in the range 10 < Q2 < 100 GeV2, grows with hadronic mass M_X and implies a dominant 2-jet topology. Thrust is found to decrease with growing Pt, the thrust jet momentum transverse to the photon-proton collision axis. Distributions of Pt2 are consistent with being independent of MX. They show a strong alignment of the thrust axis with the photon-proton collision axis, and have a large high-Pt tail. The correlation of thrust with MX is similar to that in e+e- annihilation at sqrt(see)=MX, but with lower values of thrust in the ep data. The data cannot be described by interpreting the dissociated system X as a qqbar state but inclusion of a substantial fraction of qqbarg parton configurations leads naturally to the observed properties. The soft colour exchange interaction model does not describe the data.

7 data tables

Table 1

PT distribution of the photon-originated jet relative to the to the GAMMA* P collision axis in the jet center-of-mass frame, divided by the total GAMMA* P cross section for the respective M_x bin. Jet momentum defined as vector sum of momenta in the positive(negative) thrust hemisphere (thrust jet momentum).

Table 2

Table 3

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Photoproduction of K0 and Lambda at HERA and a comparison with deep inelastic scattering.

The H1 collaboration Adloff, C. ; Aid, S. ; Anderson, M. ; et al.

Z.Phys.C 76 (1997) 213-221, 1997.

Inspire Record 443582 DOI 10.17182/hepdata.44588

Inclusive $K^0$ and $\Lambda$ photoproduction has been investigated at HERA with the H1 detector at an average photon-proton center of mass energy of 200 GeV in the transverse momentum range 0.5 <p_t <5 GeV. The production rates as a function of $p_t$ and center of mass rapidity are compared to those obtained in deep inelastic scattering at $\av{Q^2}=23 GeV^2$. A similar comparison is made of the rapidity spectra of charged particles. The rate of strangeness photoproduction is compared with $p\bar p$ measurements. The observations are also compared with next-to-leading order QCD calculations and the predictions of a Monte Carlo model.

6 data tables

Table 1

Additional systematic uncertainty given above.

Table 2

Additional systematic uncertainty given above.

Table 3

Additional systematic uncertainty given above.

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Elastic and inelastic photoproduction of J / psi mesons at HERA

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.

Nucl.Phys.B 472 (1996) 3-31, 1996.

Inspire Record 416868 DOI 10.17182/hepdata.44896

Results on \jpsi\ production in $e p$ interactionsin the H1 experiment at HERA are presented. The \jpsi\ mesons are produced by almost real photons ($Q~2\approx 0$) and detected via their leptonic decays. The data have been taken in 1994 and correspond to an integrated luminosity of $2.7\,\mbox{pb}~{-1}$. The $\gamma p$ cross section for elastic \jpsi\ production is observed to increase strongly with the \cm\ energy. The cross section for diffractive $J/\psi$ production with proton dissociation is found to be of similar magnitude as the elastic cross section. Distributions of transverse momentum and decay angle are studied and found to be in accord with a diffractive production mechanism. For inelastic \jpsi\ production the total $\gamma p$ cross section, the distribution of transverse momenta, and the elasticity of the \jpsi\ are compared to NLO QCD calculations in a colour singlet model and agreement is found. Diffractive \psiprime\ production has been observed and a first estimate of the ratio to \jpsi\ production in the HERA energy regime is given.

14 data tables

Table 1

J/PSI reconstructed via MU+ MU- decay mode.

Table 2

J/PSI reconstructed via E+ E- decay mode.

Table 3

J/PSI reconstructed via MU+ MU- decay mode.

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Photoproduction of J / psi mesons at HERA

The H1 collaboration Ahmed, T. ; Aid, S. ; Andreev, V. ; et al.

Phys.Lett.B 338 (1994) 507-518, 1994.

Inspire Record 376566 DOI 10.17182/hepdata.45103

We present a study of J ψ meson production in collisions of 26.7 GeV electrons with 820 GeV protons, performed with the H1-detector at the HERA collider at DESY. The J ψ mesons are detected via their leptonic decays both to electrons and muons. Requiring exactly two particles in the detector, a cross section of σ(ep → J ψ X) = (8.8±2.0±2.2) nb is determined for 30 GeV ≤ W γp ≤ 180 GeV and Q 2 ≲ 4 GeV 2 . Using the flux of quasi-real photons with Q 2 ≲ 4 GeV 2 , a total production cross section of σ ( γp → J / ψX ) = (56±13±14) nb is derived at an average W γp =90 GeV. The distribution of the squared momentum transfer t from the proton to the J ψ can be fitted using an exponential exp(− b ∥ t ∥) below a ∥ t ∥ of 0.75 GeV 2 yielding a slope parameter of b = (4.7±1.9) GeV −2 .

4 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

QED background subtracted.

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