Combined Electroweak and QCD Fit of Inclusive Neutral and Charged Current Data with Polarised Lepton Beams at HERA

Reference April 2016
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Contact D. Britzger
Abstract Using the final deep inelastic e+p and e-p neutral and charged current scattering cross sections from the H1 experiment, including data with polarised electron beams, a combined electroweak and QCD analysis is performed to determine vector and axial-vector couplings v_q and a_q of light quarks (u- and d-type) to the $Z^0$ boson, accounting for their correlation with parton distributions. The precision has been improved in particular for vector couplings with respect to the published results based on the unpolarised HERA-I data only. The determinations from HERA are compared with those from LEP and Tevatron. Furthermore, the Standard Model of particle physics is probed by determining simultaneously the mass values of the W and Z-bosons. Similarly, a simultaneous determination of the Fermi Coupling Constant G_F or the weak mixing angle sin^2(theta_W) together with the W-boson mass in the on-shell scheme is performed. By using the mass of the Z-boson as external input to the fits, the value of the mass of the W-boson is determined to m_W = 80.407 +/- 0.118 (exp,pdf) +/- 0.005 (m_Z,m_t,m_H) GeV. Values of the weak mixing angle in the on-shell scheme are determined at various energy scales, exploiting the large kinematic range of the data.
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