A study of CP violation in B∓→Dh∓ (h=K,π) with the modes D→K∓π±π0, D→π+π−π0 and D→K+K−π0

Thesis

One of the objectives of the LHCb experiment at CERN is a precision determination of the angle γ from the CKM Unitarity Triangle, a CP-violating parameter of the Standard Model. Sensitivity to γ can be obtained by exploiting the interference effects in B^∓→Dh^∓ (h=K,π) decays, which can lead to measurable charge asymmetries.

This thesis presents an analysis of the decays B^∓→DK^∓ and B^∓→Dπ^∓ where the D meson is reconstructed in the three-body final states of K^∓ π^± π⁰, π⁺π⁻π⁰ and K⁺K⁻π⁰. The analysis is performed using 3.0 fb⁻¹ of pp collision data collected by LHCb in 2011 and 2012. It represents the first time that these particular decay modes are studied at the LHCb experiment.

Several CP observables are measured using a simultaneous fit to the invariant B^∓ mass distributions of the decay channels of interest. A first observation is obtained of the decays B^∓→[π^∓K^±π⁰]_Dπ^∓ and B^∓→[K⁺K⁻π⁰]_Dπ^∓ at 5.3σ and greater than 10σ significance levels, respectively. In addition, first evidence of the decay B^∓→[K⁺K⁻π⁰]_DK^∓ is obtained at a significance of 4.5σ. The results are interpreted in the context of γ and related parameters.

Authors: Hussain, N

• DOI: 10.5287/ora-6roqkqbye
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: LHC; CP violation; LHCb; CERN; B physics
• Subjects: Particles (Nuclear physics); Physics