https://doi.org/10.1140/epjti/s40485-026-00121-1
Research
Improving systematic uncertainties on precision two-body mass measurements
School of Physics and Astronomy, University of Edinburgh, EH9 3FD, Edinburgh, UK
a
This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
26
November
2025
Accepted:
14
April
2026
Published online:
20
April
2026
Abstract
To make precision particle mass measurements in charged spectrometers detailed understanding of the influence of detector effects is critical. In this paper the influence of detector-related uncertainties on the determination of the parent particle mass in two-body decays is investigated. It is shown how the dependence of observed mass shifts on the sum and difference of the daughter particle momenta can be used to determine the physical causes of a bias more rigorously than the ad hoc rules that are often adopted. The approach is illustrated using the case of measuring the Λ hyperon mass. This observable is of interest because our current knowledge relies on information from a single experiment that has not been updated to account for changes in the value of the 
mass used for calibration. With the approach developed in the paper it shown that the LHCb experiment has the capability to make a measurement of the Λ mass with systematic uncertainties from the tracking system controlled to 0.7 keV/
. This allows a total precision of 2.2 keV/ to be achieved, dominated by the knowledge of the mass used for calibration. This would improve the current knowledge of the Λ hyperon mass by a factor of three.
Key words: Particle tracking / Detector calibration / Λ hyperon mass
© The Author(s) 2026
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
