Abstract
Measurements of $C\!P$ observables in $B^\pm \rightarrow D K^\pm$ and $B^\pm \rightarrow D \pi^\pm$ decays are presented where the $D$ meson is reconstructed in the final states $K^\pm\pi^\mp$, $\pi^\pm K^\mp$, $K^+K^-$, $\pi^+\pi^-$, $K^\pm\pi^\mp \pi^+ \pi^-$, $\pi^\pm K^\mp \pi^+ \pi^-$ and $\pi^+ \pi^- \pi^+ \pi^-$. This analysis uses a sample of charged $B$ mesons from $pp$ collisions collected by the LHCb experiment in 2011 and 2012, corresponding to an integrated luminosity of 3.0 fb$^{-1}$. Various \CP-violating effects are reported and together these measurements provide important input for the determination of the unitarity triangle angle $\gamma$. The analysis of the four-pion $D$ decay mode is the first of its kind.
Highlights
A set of overconstraining measurements of the unitarity triangle from the CKM matrix is central to the validation of the StandardModel (SM) description of CP violation [1]
The CP asymmetries in the favoured B− → [K −π +(π +π −)]D π − decays are fixed to zero, with a systematic uncertainty of 0.16% calculated from existing knowledge of γ and rB in this decay [18], with no assumption made about the strong phase
World-best measurements of CP observables in B− → Dh− decays are obtained with the D meson reconstructed in K −π +, K + K −, π +π −, π − K +, K −π +π +π − and π − K +π +π − final states; this supersedes earlier work [9,16]
Summary
A set of overconstraining measurements of the unitarity triangle from the CKM matrix is central to the validation of the Standard. D → π − K + decays where the interplay between the favoured and suppressed decay paths in both the B− and the neutral D decays results in a large charge asymmetry. ADS mode [6], which introduces a dependency on the ratio of the suppressed and favoured D decay amplitudes rD and their phase difference δD. Decays this dilution is parameterised in terms of a coherence factor κ K 3π , an effective strong phase difference averaged over all contributing resonances δDK 3π , and an overall suppressed-tofavoured amplitude ratio r.
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