Determination of electroweak parameters in polarised deep-inelastic scattering at HERA

V Andreev,J Kretzschmar,P R Newman,C Kleinwort,E Rizvi,E Wünsch,X Janssen,E Elsen,J Katzy,P Truöl,A W Jung,M Rotaru,M Gouzevitch,C Grab,S J Maxfield,H Meyer,H Jung,A Bylinkin,D Pitzl,E Sauvan,R Žlebčík,D Šálek,A Belousov,G Nowak,D Hoffmann,B List,D South,P Laycock,M Dobre,L Schoeffel,A Valkárová,D Krücker,A Schöning,J G Contreras,K Lipka,Z Zhang,J Meyer,V Radescu,M Sauter,V Boudry,S Schmitt,H Spiesberger,L Favart,K Krüger,G Eckerlin,F Zomer,R Polifka,P Reimer,R Kogler,C Vallée,M Klein,C Diaconu,W Lange,G Brandt,J Žáček,P Robmann,K Müller,A Fomenko,M P J Landon,T Hreus,A Morozov,A Fedotov,D Britzger,A Mehta,A Grebenyuk,R Horisberger,V Brisson,S Mikocki,A E Bolz ,B Tseepeldorj,T Greenshaw,P Van Mechelen,J Feltesse,D Ozerov,L Bystritskaya,J B Dainton,B Stella,K Daum,P D Thompson,K Černý ,T Ravdandorj,A Specka,H U Martyn ,P Kostka,D Haidt,J Gayler,M Steder,U Straumann,P Sopicki,B Łobodziński ,T Naumann ,C Niebuhr,A Lebedev,H Zohrabyan,F Sefkow,A Baghdasaryan,V Spaskov,J Cvach,Y Soloviev,E Malinovski,A Buniatyan,Y Vazdik,Jenny List ,I Pićurić ,K Begzsuren,J Hladký ,V Chekelian,D Traynor,N Raičević ,M Jacquet,Florian Huber ,R Roosen,S Levonian,I Tsakov,K B Cantun Avila,L Goerlich,A Rostovtsev,J E Olsson,T Sýkora ,S Shushkevich,C Pascaud,N Gogitidze,M Kapichine,M Fleischer,A Petrukhin,E Pérez ,A Meyer ,C Kiesling,A Campbell ,S Egli,D Wegener,G Grindhammer,G D Patel,D P C Sankey,R C W Henderson

doi:10.1140/epjc/s10052-018-6236-8

Abstract

The parameters of the electroweak theory are determined in a combined electroweak and QCD analysis using all deep-inelastic e^+p and e^-p neutral current and charged current scattering cross sections published by the H1 Collaboration, including data with longitudinally polarised lepton beams. Various fits to Standard Model parameters in the on-shell scheme are performed. The mass of the W boson is determined as m_W=80.520pm 0.115~mathrm {GeV} . The axial-vector and vector couplings of the light quarks to the Z boson are also determined. Both results improve the precision of previous H1 determinations based on HERA-I data by about a factor of two. Possible scale dependence of the weak coupling parameters in both neutral and charged current interactions beyond the Standard Model is also studied. All results are found to be consistent with the Standard Model expectations.

Highlights

Since the discovery of weak neutral currents in 1973 [1,2], the Glashow–Weinberg–Salam model [3–10] has been established as the theory of electroweak (EW) interactions and as the core of the Standard Model (SM) of particle physics
The EW parameters are determined in fits of the predictions to data, where in addition to the EW parameters of interest parameters of the parton density functions (PDFs) are determined in order to account for PDF uncertainties
The different prescriptions lead to different sensitivities of the measured cross sections to the EW parameters [73]

Summary

Introduction

Since the discovery of weak neutral currents in 1973 [1,2], the Glashow–Weinberg–Salam model [3–10] has been established as the theory of electroweak (EW) interactions and as the core of the Standard Model (SM) of particle physics. Already since these early times, deep-inelastic lepton-hadron scattering (DIS) experiments with longitudinally polarised electron beams have provided indispensable results [11,12] for its great success. EW theory has been tested in great detail at lower scales with muon life-time measurements [13] and neutrino scattering experiments [14–18], with precision measurements at the Z pole and at even higher scales [19–24]. The centre-of-mass energy at HERA nicely fills the gap between low-energy neutrino or muon experiments and highenergy collider experiments, and it offers the possibility to study neutral and charged currents (NC and CC) on equal footing

Methods

Results

Conclusion