Related papers: Parton Distribution Functions: Impact of HERA
At HERA, the large flux of almost real photons accompanying the electron beam leads to the copious photoproduction of jets. Regions of small momentum fractions $x$ of the incoming particles are explored, where the density of partons is…
In this paper an introduction to the physics of deep-inelastic scattering is given together with an account of some of the most recent results on the proton structure obtained in electron-- and positron--proton collisions at the HERA…
HERA, the first electron-proton collider, has been delivering luminosity since 1992. It is the natural extension of an impressive series of fixed-target lepton-nucleon scattering experiments. The increase of a factor ten in center-of-mass…
Recent results from the HERA experiment H1 on the longitudinal stucture function $F_{L}$ of the proton are presented. They include proton structure function analyses with particular emphasis on those kinematic regions which are sensitive to…
HERA measurements of diffractive ep scattering - the quasi-elastic scattering of the photon in the proton colour field - are summarised. Emphasis is placed on the most recent data.
We have substantially extended our analysis of the partonic content of the pomeron. Ambiguities in the normalization of the pomeron flux and the possiblity of a direct coupling of the pomeron to single quarks are discussed, yielding two…
Recent results on diffraction at HERA are presented, focusing on the measurement of the inclusive diffractive cross section and on the study of two and three jets in diffractive ep scattering.
The structure of real and virtual photons has been studied in ep collisions at HERA using dijet production. Measurements of differential dijet cross sections as function of the fraction of photon's momentum invested in the dijet system are…
Recent results on the production of open charm in electron proton scattering at HERA are reviewed. Results on the fragmentation of charm are presented and compared to the measurements at e+e- colliders. Recent results on the charm…
Use of HERA jet production cross sections can extend our knowledge of the gluon parton distribution function and yield accurate measurements of $\alpha_s(M_Z)$ in addition to illustrating the running of $\alpha_s$ with scale.
Starting in 2008 the H1 and ZEUS experiments have been combining their data in order to provide the most complete and accurate set of deep-inelastic data as the legacy of HERA. The present review presents these combinations, both published…
Data from the HERA collider experiments, H1 and ZEUS, have been fundamental to the rapid recent development of our understanding of the partonic composition of the proton and of QCD. This report focuses on inclusive measurements of neutral…
Parton distribution functions give the probability to find partons (quarks and gluons) in a hadron as a function of the fraction x of the proton's momentum carried by the parton. They are conventionally defined in terms of matrix elements…
We study photoproduction reactions in a polarized ep collider mode of HERA at sqrt(s)=298 GeV. We examine the sensitivity of the cross sections and their asymmetries to the proton's polarized gluon distribution and to the completely unknown…
The electron-proton collider HERA allows the study of the partonic content of the proton in regions of Q-squared up to 50,000 GeV$^2$ and values of Bjorken-x down to 10^-5. This paper presents recent precision measurements of structure…
Estimates for longitudinal spin asymmetries which single out new polarized nucleon structure functions in deeply inelastic charged current interactions at HERA energies are given, exploiting their interpretation in terms of polarized quark…
The HERA diffractive structure function data are interpreted in terms of `diffractive parton distributions' which satisfy DGLAP evolution. These distributions are modeled assuming that the scattering takes place off a colour singlet…
I review the current status of the determination of helicity-dependent, or polarized, parton distribution functions from a comprehensive analysis of experimental data in perturbative quantum chromodynamics. I illustrate the latest…
The $e^{+}p$ and $e^{-}p$ scattering data recorded at HERA during the recent years offer the possibility to study electroweak effects in $ep$ interactions apparent at high momentum transfers, $Q^{2}$, and to reveal information on the proton…
HERA $ep$ collider provides unique information on the proton structure. High center of mass energy $s=320$ GeV gives access to both the low Bjorken-$x$ domain and regime of high momentum transfers $Q$. Recently the H1 collaboration reported…