Standard model Precision Electroweak tests at Acute Rapidities

Project Information

SPEAR

Grant agreement ID: 865469

DOI

10.3030/865469

Project closed

EC signature date 30 January 2020

Start date 1 June 2020

End date 31 May 2026

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 875 781,00

EU contribution

€ 1 875 781,00

Coordinated by

UNIVERSITY OF WARWICK
United Kingdom

Periodic Reporting for period 3 - SPEAR (Standard model Precision Electroweak tests at Acute Rapidities)

Reporting period: 2023-06-01 to 2024-11-30

Summary of the context and overall objectives of the project

The electroweak SM theory describes the electromagnetic and weak-nuclear forces in terms of three fundamental parameters.
A global fit of observables that relate to these parameters is sensitive to quantum-loop corrections involving possible fields beyond those of the SM.
Gaining a deeper understanding of the fundamental forces of nature is especially important for society since it has proven to lead to technological breakthroughs throughout history.
The discovery of physics beyond the SM is a holy grail in physics.
The sensitivity of this test is primarily limited by the precision of the measurement of the W boson mass.
The SPEAR project aims to exploit a previously unforeseen potential of the LHCb experiment in a new measurement of the W boson mass.
The project also aims to make a precision determination of a related parameter, the weak mixing angle, and a test of lepton universality with
W boson decays.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Within the first year of the project my team has delivered a first proof-of-principle measurement of the W boson mass with the LHCb experiment,
which was reported as a preliminary result in the prestigious CERN seminar series https://indico.cern.ch/event/1027304/.
This result was also one of the highlights in the bi-annual European Physical Society summer conference that followed soon after the CERN seminar.
This provides an solid foundation for achieving the objectives of WP1 of the project.
A scientific paper describing this analysis is now in the final stages of editorial review within the LHCb experiment, before it is submitted to a peer-reviewed
open access journal.
All team members have already presented the results at workshops, meetings and conferences.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Within the first year of the project the first proof-of-principle measurement of the W boson mass already introduces several novel methodologies that are unique to this analysis.
This includes a simultaneous measurement of the W boson mass and a W-specific tune of event generators.
The analysis also made use of a simple new method for controlling charge-dependent curvature biases, which was developed by the PI
with collaborators https://link.springer.com/article/10.1140%2Fepjc%2Fs10052-021-09016-9.

Title slide from CERN seminar on measurement of the W boson mass