Neutral Current Deep Inelastic Scattering Research Articles

Jet Production at HERA and Determination of [formula omitted

Inclusive jet, dijet and trijet differential cross sections are measured [H1 Collab., DESY-14-089, [arXiv:1406.4709]] in neutral current deep-inelastic scattering (DIS) for exchanged boson virtualities 150<Q2<15000 GeV2 using the H1 detector at HERA. The data were taken in the years 2003 to 2007 and correspond to an integrated luminosity of 351pb−1. Jet cross sections are obtained using a regularised unfolding procedure. Normalised differential jet cross sections are also measured as the ratio of the jet cross sections to the inclusive neutral current cross sections in the respective Q2 bins of the jet measurements. The cross sections are used to determine the strong coupling constant αs=0.1165 (8)exp (38)pdf,theo.Trijet differential cross sections are measured [ZEUS Collab., ZEUS-prel-14-008] in neutral current DIS for 125<Q2<20000 GeV2 using the ZEUS detector at HERA. Good agreement between data and NLO calculations is observed.

Nuclear effects on the extraction of sin2θW

We study the impact of nuclear effects on the extraction of the weak-mixing angle sin2θW from deep inelastic (anti-)neutrino–nucleus scattering, with special emphasis on the recently announced NuTeV Collaboration 3σ deviation of sin2θW from its standard model value. We have found that nuclear effects, which are very important in electromagnetic deep inelastic scattering (DIS), are quite small in weak charged current DIS. In neutral current DIS processes, which contain the weak mixing angle, we predict that these effects play also an important role and may dramatically affect the value of sin2θW extracted from the experimental data.

Heavy quark fragmentation in deep inelastic scattering

We perform an analysis of semi-inclusive production of charm (D-mesons) in neutral current (NC) and charged current (CC) deep inelastic scattering (DIS) at full O(alpha_s^1). Our calculation is based on the heavy quark scheme developed by Aivazis, Collins, Olness and Tung (ACOT) where we include an O(alpha_s^1) calculation of quark scattering contributions for general masses and couplings. We review the relevant massive formulae and subtraction terms and discuss their massless limits. We show how the charm fragmentation function can be measured in CC DIS and we investigate whether the charm production dynamics may be tested in NC DIS. We also discuss finite initial state quark mass effects in CC and NC DIS.

High Q2 physics at HERA and searches for new particles

Preliminary results from H1 and ZEUS on e+p scattering at high momentum transfer squared, Q2, are presented, using all available data accumulated by the H1 and ZEUS experiments between 1994-97, corresponding to integrated luminosities of 37 pb-1 and 47 pb-1, respectively. The anomalies observed at high Q2 in the 1994-96 data remain, though with less significance. Since this high Q2 domain represents a new frontier in deep inelastic scattering (DIS), these data are used to search for new particles possessing direct couplings to lepton-quark pairs. Assuming that the slight excess of events observed in neutral current DIS is due to a statistical fluctuation, preliminary limits on the production of leptoquarks and of squarks in R-parity violating the minimal supersymmetric standard model are presented.