A study of CP violation and measurement of the CKM angle γ in B0→ DK∗0 decays

Thesis

Two measurements of CP observables in B⁰ → DK^∗0 decays are presented, where D represents a superposition of D⁰ and D⁰-bar states. The measurements use samples of proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV.

The first measurement uses 5 fb⁻¹ of data with the D meson reconstructed in the two-body final states K⁺π⁻, π⁺K⁻, K⁺K^-, and π⁺π⁻, and, for the first time, in the four-body final states K⁺π⁻π⁺π⁻, π⁺K⁻π⁺π^-, and π⁺π^-π⁺π⁻. First observations of the decays B0 → D(π⁺K−)K∗0 and B0 → D(π⁺π⁻π⁺π−)K∗0 are obtained, and a set of observables comprising yield ratios and asymmetries is studied. The second measurement studies D-meson decays to the three-body final states K_S⁰π+π⁻ and K_S⁰K⁺K⁻ in a binned Dalitz plot analysis using 9 fb⁻¹ of data.

The CP observables from both measurements are interpreted together to determine the CP-violating weak phase γ = (77⁺⁸_-9)◦. This is the world’s most precise determination using only B0-meson decays and is in agreement with the prediction of the Standard Model. The world’s best measurements of the hadronic parameters r_B = 0.258^+0.022_-0.023 and δ_B0 = (200 ± 8)◦ are also presented.

Authors: Pullen, HL

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: CP violation; B mesons; Large Hadron Collider; CKM triangle
• Subjects: Experimental particle physics; High energy physics