Combined Electroweak and QCD Fit to HERA data
Physical Review D American Physical Society 94:5 (2016)
Abstract:
A simultaneous electroweak and QCD fit of electroweak parameters and parton distribution functions to HERA data on deep inelastic scattering is presented. The input data are neutral current and charged current inclusive cross sections measured by the H1 and ZEUS collaborations at the $ep$ collider HERA. The polarization of the electron beam was taken into account for the ZEUS and H1 data recorded between 2004 and 2007. Results are presented on the vector and axial-vector couplings of the $Z$ boson to $u-$ and $d-$type quarks. The values are in agreement with Standard Model predictions. The results on $au$ and $vu$ represent the most precise measurements from a single process.Study of HERA ep data at low Q(2) and low x(Bj) and the need for higher-twist corrections to standard perturbative QCD fits
PHYSICAL REVIEW D 94:3 (2016) ARTN 034032
Search for a narrow baryonic state decaying to pK0 S and pK0 S in deep inelastic scattering at HERA
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics Elsevier 759 (2016) 446-453
Abstract:
A search for a narrow baryonic state in the pKS0 and pKS0 system has been performed in ep collisions at HERA with the ZEUS detector using an integrated luminosity of 358pb-1 taken in 2003-2007. The search was performed with deep inelastic scattering events at an ep centre-of-mass energy of 318GeV for exchanged photon virtuality, Q2, between 20 and 100GeV2. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb-1 taken in 1996-2000, no resonance peak was found in the p(p)KS0 invariant-mass distribution in the range 1.45-1.7 GeV. Upper limits on the production cross section are set.Measurement of the cross-section ratio σψ(2S)/σJ/ψ(1S) in deep inelastic exclusive ep scattering at HERA
Nuclear Physics B Elsevier (2016)
Abstract:
The exclusive deep inelastic electroproduction of ψ(2S) and J/ψ(1S) at an ep centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range 2 < Q2 < 80 GeV2, 30 <W< 210 GeV and |t| < 1 GeV2, where Q2 is the photon virtuality, W is the photon–proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The data for 2 < Q2 < 5 GeV2 were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb−1. The data for 5 < Q2 < 80 GeV2 are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb−1. The decay modes analysed were μ+μ− and J/ψ(1S)π+π− for the ψ(2S) and μ+μ− for the J/ψ(1S). The cross-section ratio σψ(2S)/σJ/ψ(1S) has been measured as a function of Q2, W and t. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.Combined QCD and electroweak analysis of HERA data
Physical Review D American Physical Society 93 (2016) 092002