Measurement of MW+ - MW- at LHC

TL;DR

This paper proposes a robust LHC-specific method to measure the charge asymmetry of W-boson masses, significantly improving precision over traditional methods and enabling fundamental tests of the Standard Model.

Contribution

It introduces a novel strategy for measuring the W-boson charge mass difference at the LHC with 20 times higher precision than existing techniques.

Findings

Current precision can be improved by a factor of 20.

The method surpasses standard calibration approaches.

It provides a crucial test of W-boson charge symmetry.

Abstract

This paper is the second of the series of papers proposing dedicated strategies for precision measurements of the Standard Model parameters at the LHC. The common feature of these strategies is their robustness with respect to the systematic measurement and modeling error sources. Their impact on the precision of the measured parameters is reduced using dedicated observables and dedicated measurement procedures which exploit flexibilities of the collider and detector running modes. In the present paper we focus our attention on the measurement of the charge asymmetry of the W-boson mass. This measurement is of primordial importance for the LHC experimental program, both as a direct test of the charge-sign-independent coupling of the W-bosons to the matter particles and as a necessary first step towards the precision measurement of the charge-averaged W-boson mass. We propose and evaluate the LHC-specific strategy to measure the mass difference between the positively and negatively charged W-bosons, MW+ - MW-. We show that its present precision can be improved at the LHC by a factor of 20. We argue that such a precision is beyond the reach of the standard measurement and calibration methods imported to the LHC from the Tevatron program.