Structure of the hadronic neutral current and parameters of the standard model from an analysis of the neutrino-induced deep-inelastic scattering

An updated and refined analysis of the structure of the hadronic neutral current in the neutrino-induced deep-inelastic scattering is reported. Starting from a careful treatment of the most recent neutrino charged current data, a reparametrization of the nucleon structure functions is performed including all effects such as QCD evolution, longitudinal structure function, quark mixing, slow rescaling, radiative corrections, and so on. The errors induced by the theoretical approach on the final estimate are conveniently introduced together with their correlations. Starting from all available experimental data concerning both isoscalar and non-isoscalar targer (43 independent experimental results are included in the analysis), through an analytic procedure the four squared chiral couplings are derived: the modelindependent analysis leads to $$begin{gathered} u_L^2 = 0.1197 pm 0.0116( pm 0.0008), hfill d_L^2 = 0.1785 pm 0.0119( pm 0.0035), hfill u_R^2 = 0.0257 pm 0.0081( pm 0.0014), hfill d_R^2 = 0.0052 pm 0.0078( pm 0.0030), hfill end{gathered} $$ where the first error comes from the experimental errors affecting the different measurements (with quadratic addition of statistical and systematic errors) and the second one is the theoretical error induced by the uncertainties in the parametrization. A comparison with the standard model is then performed. If ρ=1 is 0.0029 (±0.0024) is obtained for fixedc-quark mass. If the assumption ρ=1 is relaxed, the simultaneous estimate of both parameters leads to sin² θ _W =0.2346±0.0105(±0.0079) and ρ=1.0036±0.0099 (±0.0064). A comparison with the case in which radiative corrections are not included is also considered. Furthermore, constraints on the masses of the charm and top are derived. By using the slow rescaling to describe the threshold effect induced bym _c within the minimal standard model,m _c =1.54±0.33, is obtained. In an analogous way, starting from the effects induced by them _t -dependent terms in the radiative corrections, the upper limitm _t <267 (291) GeV (with and without the inclusion of the uncertainties due to the parametrization) at 90% C.L. is found.