Limits on the effective quark radius from inclusive ep scattering at HERA
Physics Letters B Elsevier 757 (2016) 468-472
Abstract:
The high-precision HERA data allows searches up to TeV scales for beyond the Standard Model contributions to electron–quark scattering. Combined measurements of the inclusive deep inelastic cross sections in neutral and charged current ep scattering corresponding to a luminosity of around 1 fb−1 have been used in this analysis. A new approach to the beyond the Standard Model analysis of the inclusive ep data is presented; simultaneous fits of parton distribution functions together with contributions of “new physics” processes were performed. Results are presented considering a finite radius of quarks within the quark form-factor model. The resulting 95% C.L. upper limit on the effective quark radius is 0.43⋅10−16 cm.Particle physics after the Higgs
Annalen der Physik Wiley 528:1-2 (2016) 16-19
Production of exclusive dijets in diffractive deep inelastic scattering at HERA
European Physical Journal C Springer Berlin Heidelberg 76:1 (2016) 1-18
Abstract:
Production of exclusive dijets in diffractive deep inelastic e±p scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb-1. The measurement was performed for γ∗–p centre-of-mass energies in the range 90Combination of Measurements of Inclusive Deep Inelastic e+/- Scattering Cross Sections and QCD Analysis of HERA Data
European Physical Journal C: Particles and Fields Springer Verlag (Germany): SCOAP3 (2015)
Abstract:
A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current e±p scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb−1 and span six orders of magnitude in negative four-momentum-transfer squared, Q2, and Bjorken x. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, next-to-leading order and at next-to-next-to-leading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisation, HERAPDF2.0AG, and using fixed-flavour-number schemes, HERAPDF2.0FF, are presented. The analysis was extended by including HERA data on charm and jet production, resulting in the variant HERAPDF2.0Jets. The inclusion of jet-production cross sections made a simultaneous determination of these parton distributions and the strong coupling constant possible, resulting in αs(MZ)=0.1183±0.0009(exp)±0.0005(model/parameterisation)±0.0012(hadronisation)+0.0037−0.0030(scale). An extraction of xFγZ3 and results on electroweak unification and scaling violations are also presented.Combination of measurements of inclusive deep inelastic e±p scattering cross sections and QCD analysis of HERA data: H1 and ZEUS Collaborations
European Physical Journal C Springer Verlag (2015)