On the Effect of Asymmetric Strange Seas and Isospin-Violating Parton Distribution Functions on sin2thetaW Measured at NuTeV

TL;DR

This paper investigates how asymmetries in strange quark seas and isospin violations in parton distributions could explain the NuTeV anomaly in measuring sin2thetaW, challenging standard assumptions in neutrino scattering analyses.

Contribution

It analyzes the effects of asymmetric strange seas and isospin violations on sin2thetaW, providing insights into potential sources of the NuTeV discrepancy.

Findings

Asymmetries can significantly shift sin2thetaW measurements.

Violations of assumed symmetries may account for the NuTeV anomaly.

Constraints on asymmetries are discussed in context of experimental data.

Abstract

The NuTeV collaboration recently reported a value of sin2thetaW measured in neutrino-nucleon scattering that is 3 standard deviations above the standard model prediction. This result is derived assuming that (1) the strange sea is quark-antiquark symmetric, s(x)=sbar(x), and (2) up and down quark distributions are symmetric under the simultaneous interchange of u<->d and p<->n. We report the impact of violations of these symmetries on sin2thetaW and discuss the theoretical and experimental constraints on such asymmetries.