Amplitude analysis of the B 0 → D 0 D 0 Kπ decay with the LHCb experiment

Abstract

The B 0 → D 0 D 0 Kπ decay offers an opportunity to investigate charm-loop contributions to
measurements currently in tension with the SM, as well as search for and measure the properties
of exotic states. An amplitude analysis of the B 0 → D 0 D 0 Kπ decay is performed using proton-
proton collision data from the LHCb experiment at CERN, using data collected during LHC
Runs I & II. The signal selection pipeline is based on the selections introduced in the first
observation and branching fraction measurement of the decay mode, from which an estimated
total of 1388 ± 43 signal and 243 ± 8 background events are observed. An unbinned maximum
likelihood fit is performed simultaneously across 12 subsets of the data, with the background
modelled using a neural network, and model components chosen using the LASSO method.
The resulting amplitude model was assessed for the presence of three known exotic states, all
of which appear to be present in the data with a statistical significance of > 4σ. However, the
resulting amplitude model is insufficient to adequately describe the data, and the analysis is
statistically limited. The next steps include systematically reviewing possible intermediate state
properties that could result in the shapes seen in the data, and processing Run III data. In
addition, this thesis outlines the alignment of the photodetector panels in the upgraded RICH
detectors for Run III.

Date of Award	18 Mar 2025
Original language	English
Awarding Institution	University of Bristol
Supervisor	Konstantinos A. Petridis (Supervisor) & Jonas H Rademacker (Supervisor)