arXiv subjects

H1-Collaboration

Publications and source records attributed to H1-Collaboration.

4 recordsLinked to original sources

arXiv2007

Three- and Four-jet Production at Low x at HERA

Three- and four-jet production is measured in deep-inelastic $ep$ scattering at low $x$ and $Q^2$ with the H1 detector using an integrated luminosity of $44{.}2 {\rm pb}^{-1}$. 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 ${\mathcal{O}}(α_{\rm s}^2)$ and ${\mathcal{O}}(α_{\rm 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}}(α_{\rm s}^3) $ calculation. Too few events are predicted at the lowest $x \sim 10^{-4}$, 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.

hep-ex↗

arXiv1995

Jets and Energy Flow in Photon-Proton Collisions at HERA

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to $\overline{p}p$ data and QCD calculations. The comparisons show that the $γp$ events can be consistently described by QCD models including -- in addition to the primary hard scattering process -- interactions between the two beam remnants. The differential jet cross sections $dσ/dE_T^{jet}$ and $dσ/dη^{jet}$ are measured.

hep-ex↗

arXiv1995

Comparison of Deep Inelastic Scattering with Photoproduction Interactions at HERA

Photon-proton ($γp$) interactions with~$Q^2<10^{-2}$~GeV$^2$ and deep-inelastic scattering ($γ^* p$) interactions with photon virtualities $Q^2>5$~GeV$^2$ are studied at the high energy electron-proton collider HERA. The transverse energy flow and relative rates of large rapidity gap events are compared in the two event samples. The observed similarity between $γp$ and $γ^* p$ interactions can be understood in a picture where the photon develops as a hadronic object. The transverse energy density measured in the central region of the collision, at $η^*=0$ in the $γ^* p$ centre of mass frame, is compared with data from hadron-hadron interactions as function of the CMS energy of the collision.

hep-ex↗

arXiv1995

First Measurement of the Deep--Inelastic Structure of Proton Diffraction

A measurement is presented, using data taken with the H1 detector at HERA, of the contribution of diffractive interactions to deep-inelastic electron-proton scattering. The diffractive contribution to the proton structure function is evaluated as a function of the appropriate deep-inelastic scattering variables using a class of deep-inelastic ep scattering events with no hadronic energy flow in an interval of pseudo-rapidity adjacent to the proton beam direction. The dependence of this contribution on x-pomeron is consistent with both a diffractive interpretation and a factorisable ep diffractive cross section. A first measurement of the deep-inelastic structure of the pomeron in the form of a factorised structure function is presented. This structure function is observed to be consistent with scale invariance.

hep-ex↗