H. Lueders

The diffractive photoproduction of J/psi mesons is measured with the H1 detector at the ep collider HERA using an integrated luminosity of 78 pb^-1. The differential cross section d sigma(gamma p -> J/psi Y) / d t is studied in the range 2 < |t| < 30 GeV^2, where t is the square of the four-momentum transferred at the proton vertex. The cross section is also presented as a function of the photon-proton centre-of-mass energy W in three t intervals, spanning the range 50 < W < 200 GeV. A fast rise of the cross section with W is observed for each t range and the slope for the effective linear Pomeron trajectory is measured to be alpha^\prime= -0.0135 \pm 0.0074 (stat.) \pm 0.0051 (syst.) GeV^-2. The measurements are compared with perturbative QCD models based on BFKL and DGLAP evolution. The data are found to be compatible with s-channel helicity conservation.

Perturbative QCD

Pomeron

Helicity

Momentum transfer

10.1016/j.physletb.2003.06.056

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Citations (55)

Search for bosonic stop decays in R-parity violating supersymmetry in e+p collisions at HERA

Physics Letters B (2004)

Å. Aktas V. Andreev T. Anthonis A. Asmone A. Babaev

Yukawa potential

R-parity

Parity (physics)

10.1016/j.physletb.2004.08.032

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Citations (13)

Photoproduction of dijets with high transverse momenta at HERA

Physics Letters B (2006)

Å. Aktas V. Andreev T. Anthonis B. Antunović S. Aplin

10.1016/j.physletb.2006.05.060

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Citations (23)

Tests of QCD factorisation in the diffractive production of dijets in deep-inelastic scattering and photoproduction at HERA

The European Physical Journal C (2007)

Å. Aktas V. Andreev T. Anthonis B. Antunović S. Aplin

10.1140/epjc/s10052-007-0325-4

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Citations (81)

Forward $\pi^\circ$ production and associated transverse energy flow in deep-inelastic scattering at HERA

The European Physical Journal C (2004)

Å. Aktas H. Henschel W. Erdmann R. Weber P. Dixon

Energy Flow

10.1140/epjc/s2004-01983-1

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Citations (21)

Search for doubly-charged Higgs boson production at HERA

Physics Letters B (2006)

Å. Aktas V. Andreev T. Anthonis B. Antunović S. Aplin

A search for the single production of doubly-charged Higgs bosons H^{\pm \pm} in ep collisions is presented. The signal is searched for via the Higgs decays into a high mass pair of same charge leptons, one of them being an electron. The analysis uses up to 118 pb^{-1} of ep data collected by the H1 experiment at HERA. No evidence for doubly-charged Higgs production is observed and mass dependent upper limits are derived on the Yukawa couplings h_{el} of the Higgs boson to an electron-lepton pair. Assuming that the doubly-charged Higgs only decays into an electron and a muon via a coupling of electromagnetic strength h_{e \mu} = \sqrt{4 \pi \alpha_{em}} = 0.3, a lower limit of 141 GeV on the H^{\pm\pm} mass is obtained at the 95% confidence level. For a doubly-charged Higgs decaying only into an electron and a tau and a coupling h_{e\tau} = 0.3, masses below 112 GeV are ruled out.

Yukawa potential

Pair production

10.1016/j.physletb.2006.05.061

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Citations (31)