Visualisation of -violation effects in decay-time-dependent analyses of multibody B-meson decays

Tim Gershon; Thomas Latham; Andy Morris; Wenbin Qian; Mark Whitehead; Ao Xu

doi:10.1140/epjc/s10052-024-12615-x

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2024) 84: 327
https://doi.org/10.1140/epjc/s10052-024-12615-x

Regular Article - Experimental Physics

Visualisation of $C P$ $C\!P$ -violation effects in decay-time-dependent analyses of multibody B-meson decays

Tim Gershon¹^a, Thomas Latham¹, Andy Morris², Wenbin Qian³, Mark Whitehead⁴ and Ao Xu⁵

¹ University of Warwick, Coventry, UK
² Aix Marseille Univ, CNRS/IN2P3 CPPM, Marseille, France
³ University of Chinese Academy of Sciences, Beijing, China
⁴ School of Physics and Astronomy, University of Glasgow, Glasgow, UK
⁵ INFN Sezione di Pisa, Pisa, Italy

^a T.J.Gershon@warwick.ac.uk

Received: 24 January 2024
Accepted: 25 February 2024
Published online: 28 March 2024

Abstract

Decay-time-dependent $C P$ $C\!P$ -violation effects in transitions of neutral B mesons to $C P$ $C\!P$ -eigenstates can be visualised by oscillations in the asymmetry, as a function of decay time, between decay yields from mesons tagged as initially having $\bar{B}$ ${\hspace{0.0pt}\overline{\hspace{0.0pt}{B}}}$ or B flavour. Such images, for example for $B^{0} \to J / ψ K_{S}^{0}$ $B^0 \rightarrow {{{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\uppsi }} {{{K}} ^0_{\textrm{S}}}$ decays where the magnitude of the oscillation is proportional to $sin (2 β)$ $\sin (2\beta )$ with $β$ $\beta$ being an angle of the Cabibbo–Kobayashi–Maskawa Unitarity Triangle, provide a straightforward illustration of the underlying physics. Until now there has been no comparable method to provide visualisation for the case of decays to multibody final states that are not $C P$ $C\!P$ -eigenstates, where interference between $C P$ $C\!P$ -even and -odd amplitudes provides additional physics sensitivity. A method is proposed to weight the data so that the terms of interest can be projected out and used to obtain asymmetries that visualise the relevant effects. Application of the weighting to $B_{s}^{0}$ ${{B}} ^0_{\textrm{s}}$ decays, where effects due to non-zero width difference are not negligible, provides a novel method to observe $C P$ $C\!P$ violation in interference between mixing and decay without tagging the production flavour.

© The Author(s) 2024

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/.