Thesis defense of Louis Lenard Gerken

In this thesis, two measurements of CP violation in the B→DD system are presented. Both analyses explore proton-proton collision data corresponding to an integrated luminosity of 6 fb-1 collected by the LHCb experiment at a centre-of-mass energy of 13 TeV.

The flavour-tagged decay-time-dependent analysis of about 5700 B0→D+D- signal candidates yields the CP observables

S_D+D- = -0.552 ± 0.100 (stat) ± 0.010 (syst),
C_D+D- =  0.128 ± 0.103 (stat) ± 0.010 (syst).

In the second measurement, approximately 13000 Bs0→Ds+Ds- signal candidates are selected, and the CP observables are determined to be

ϕsDs+Ds- = -0.086 ± 0.106 (stat) ± 0.028 (syst) rad,
|λDs+Ds-| = 1.145 ± 0.126 (stat) ± 0.031 (syst).

These results represent the most precise measurements of CP violation in their respective channels to date and are consistent with Standard Model predictions. For the first time, CP symmetry in B0→D+D- decays is excluded by a single measurement with a significance of more than six standard deviations.

Back