Electroweak radiative corrections to neutrino-nucleon scattering
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The main subject of this thesis is to study the impact of electroweak [Special characters omitted.] <math> <f> <sc>O</sc></f> </math> (α) corrections on neutrino-nucleon scattering processes, in particular on the extraction of electroweak parameters at the NuTeV experiment. The Standard Model (SM) represents the best current understanding of electroweak and strong interactions of elementary particles. In recent years it has been impressively confirmed experimentally through the precise determination of W and Z boson properties at the CERN LEP and the Stanford Linear e + e - colliders, and the discovery of the top quark at the Fermilab Tevatron pp collider. The W boson mass ( M W ) is one of the fundamental parameters in electroweak theory. A precise measurement of M W does not only provide a further precisely known SM input parameter, but significantly improves the indirect limit on the Higgs-boson mass obtained by comparing SM predictions with electroweak precision data. M W is measured directly at the CERN LEP2 e + e - and the Fermilab Tevatron pp colliders. A measurement of M W can also be extracted from a measurement of the sine squared of the weak mixing angle, i.e. sin 2 [straight theta] W , via the well-known relation between the W and Z boson mass, [Special characters omitted.] <math> <f> M<sup>2</sup><inf>W</inf>=M<sup>2</sup><inf>Z</inf></f> </math> (1 - sin 2 [straight theta] W ). The NuTeV collaboration  extracts sin 2 [straight theta] W , and thus M W , from the ratio of neutral and charged-current neutrino and anti-neutrino cross sections. Their result differs from direct measurements performed at LEP2 and the Fermilab Tevatron by about 3σ. Much effort both experimental and theoretical has gone into understanding this discrepancy. These efforts include QCD corrections, parton distribution functions, and nuclear structure . However, the effect of electroweak radiative corrections has not been fully studied yet. In the extraction of M W from NuTeV data, only part of the electroweak corrections have been included . Although the complete calculation of these corrections is available in  and , their impact on the NuTeV measurement of M W is not yet known. In an attempt to answer this question, we calculated the complete electroweak [Special characters omitted.] <math> <f> <sc>O</sc></f> </math> (α) corrections to neutrino-nucleon scattering and studied their impact on sin 2 [straight theta] W and M W measured by the NuTeV collaboration. We included in our calculation the full fermion-mass dependence, which has not been studied before. The result of the NuTeV collaboration is based on a calculation that neglects fermion masses whenever possible, i.e., they only keep fermion masses as regulators, as we have done when obtaining the massless result. We found that using the calculation with full fermion-mass dependence shifts sin 2 [straight theta] W by -0.0064(5) and consequently M W by +0.331(3) compared to the result obtained when considering massless fermions. Such a shift brings the NuTeV measurement of M W closer to the world average and thus could resolve the NuTeV anomaly. However, a more realistic study is needed including a simulation of the detector resolution, for instance.