The first measurement of diffractive scattering of quasi-real photons with large momentum transfer γp→γY, where Y is the proton dissociative system, is made using the H1 detector at HERA. The measurement is performed for initial photon virtualities Q2<0.01GeV2. Single differential cross sections are measured as a function of W, the incident photon–proton centre of mass energy, and t, the square of the four-momentum transferred at the proton vertex, in the range 175

Momentum transfer

Perturbative QCD

Momentum (technical analysis)

10.1016/j.physletb.2009.01.019

Cite

Citations (10)

Measurement of inclusive and dijet D∗ meson cross sections in photoproduction at HERA

The European Physical Journal C (2012)

F. D. Aaron C. Alexa V. Andreev S. Backović A. Baghdasaryan

The inclusive photoproduction of D\ast mesons and of D\ast-tagged dijets is investigated with the H1 detector at the ep collider HERA. The kinematic region covers small photon virtualities Q2 < 2 GeV2 and photon-proton centre-of-mass energies of 100 < Wgp < 285 GeV. Inclusive D\ast meson differential cross sections are measured for central rapidities |eta(D\ast)| < 1.5 and transverse momenta pT (D\ast) > 1.8 GeV. The heavy quark production process is further investigated in events with at least two jets with transverse momentum pT (jet) > 3.5 GeV each, one containing the D\ast meson. Differential cross sections for D\ast-tagged dijet production and for correlations between the jets are measured in the range |eta(D\ast)| < 1.5 and pT (D\ast) > 2.1 GeV. The results are compared with predictions from Monte Carlo simulations and next-to-leading order perturbative QCD calculations.

Perturbative QCD

D meson

10.1140/epjc/s10052-012-1995-0

Cite

Citations (10)

Inclusive D*± meson cross sections and D*±-jet correlations in photoproduction at HERA

The European Physical Journal C (2007)

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

Perturbative QCD

ZEUS (particle detector)

D meson

10.1140/epjc/s10052-007-0220-z

Cite

Citations (14)

Diffractive photoproduction of J/ψ mesons with large momentum transfer at HERA

Physics Letters B (2003)

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

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

Cite

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

Cite

Citations (13)

Three- and four-jet production at low x at HERA

The European Physical Journal C (2008)

F. D. Aaron Å. Aktas C. Alexa Vladimir Andreev B. Antunović

Three- and four-jet production is measured in deep-inelastic ep scattering at low x and Q2 with the H1 detector using an integrated luminosity of 44.2 pb-1. Several phase space regions are selected for the three-jet analysis in order to study the underlying parton dynamics from global topologies to the more restrictive regions of forward jets close to the proton direction. The measurements of cross sections for events with at least three jets are compared to fixed order QCD predictions of ${\mathcal{O}}(\alpha_{{\text{s}}}^2)$ and ${\mathcal{O}}(\alpha_{{\text{s}}}^3)$ and with Monte Carlo simulation programs where higher order effects are approximated by parton showers. A good overall description is provided by the ${\mathcal{O}}(\alpha_{{\text{s}}}^3)$ calculation. Too few events are predicted at the lowest x∼10-4, especially for topologies with two forward jets. This hints to large contributions at low x from initial state radiation of gluons close to the proton direction and unordered in transverse momentum. The Monte Carlo program in which gluon radiation is generated by the colour dipole model gives a good description of both the three- and the four-jet data in absolute normalisation and shape.

Momentum (technical analysis)

10.1140/epjc/s10052-008-0544-3

Cite

Citations (4)

Measurement of D ∗± meson production and determination of $F_{2}^{c\bar{c}}$ at low Q 2 in deep-inelastic scattering at HERA

The European Physical Journal C (2011)

F. D. Aaron C. Alexa V. Andreev S. Backović A. Baghdasaryan

Inclusive production of D ∗ mesons in deep-inelastic ep scattering at HERA is studied in the range 51.25 GeV and |η(D ∗)|<1.8. The data sample corresponds to an integrated luminosity of 348 pb−1 collected with the H1 detector. Single and double differential cross sections are measured and the charm contribution ${F_{2}^{c\bar{c}}}$ to the proton structure function F 2 is determined. The results are compared to perturbative QCD predictions at next-to-leading order implementing different schemes for the charm mass treatment and with Monte Carlo models based on leading order matrix elements with parton showers.

Perturbative QCD

D meson

10.1140/epjc/s10052-011-1769-0

Cite

Citations (55)

Multi-lepton production at high transverse momenta in ep collisions at HERA

Physics Letters B (2008)

F. D. Aaron C. Alexa Vladimir Andreev B. Antunović S. Aplin

Processes leading to a final state with at least two high transverse momentum leptons (electrons or muons) are studied using the full e±p data sample collected by the H1 experiment at HERA. The data correspond to an integrated luminosity of 463 pb−1. Di-lepton and tri-lepton event classes are investigated. Cross sections of the production of e+e− and μ+μ− pairs are derived in a restricted phase space dominated by photon–photon collisions. In general, good agreement is found with Standard Model predictions. Events are observed with a total scalar sum of lepton transverse momenta above 100GeV where the Standard Model expectation is low. In this region, combining di-lepton and tri-lepton classes, five events are observed in e+p collisions, compared to a Standard Model expectation of 0.96±0.12, while no such event is observed in e−p data for 0.64±0.09 expected.

10.1016/j.physletb.2008.08.057

Cite

Citations (21)