Abstract
A measurement of CP-violating observables is performed using the decays B± → DK± and B± → Dπ±, where the D meson is reconstructed in one of the self-conjugate three-body final states {K}_{mathrm{S}}^0 π+π− and {K}_{mathrm{S}}^0 K+K− (commonly denoted {K}_{mathrm{S}}^0 h+h−). The decays are analysed in bins of the D-decay phase space, leading to a measurement that is independent of the modelling of the D-decay amplitude. The observables are inter- preted in terms of the CKM angle γ. Using a data sample corresponding to an integrated luminosity of 9 fb−1 collected in proton-proton collisions at centre-of mass energies of 7, 8, and 13 TeV with the LHCb experiment, γ is measured to be left({68.7}_{-5.1}^{+5.2}right){}^{circ} . The hadronic parameters {r}_B^{D K},{r}_B^{Dpi},{delta}_B^{D K},kern0.5em mathrm{and}kern0.5em {delta}_B^{Dpi} , which are the ratios and strong-phase differences of the suppressed and favoured B± decays, are also reported.
Highlights
The hadronic parameters rBDK, rBDπ, δBDK, and δBDπ, which are the ratios and strong-phase differences of the suppressed and favoured B± decays, are reported
This paper presents a model-independent study of the decay modes B± → DK± and B± → Dπ± where the chosen D decays are the self-conjugate decays D → KS0π+π− and D → KS0K+K−
The loss in statistical precision is compensated by reliability in the evaluation of the systematic uncertainty, which is increasingly important as the overall precision on the CKM angle γ improves
Summary
The sum of the favoured and suppressed contributions to the B− → DK− amplitude can be written as AB(m2−, m2+) ∝ AD(m2−, m2+) + rBDK ei(δBDK−γ)AD(m2−, m2+),. The global asymmetry is ignored and the loss of information is minimal An advantage of this approach is that the normalisation constants hB+ and hB− are independent of each other, and will implicitly contain the effects of the production asymmetry of B± mesons in pp collisions and the detection asymmetries of the charged kaon from the B decay. The measurements of ci and si are available in four different 2 × 8 binning schemes for the D → KS0π+π− decay This analysis uses the scheme called the optimal binning, where the bins have been chosen to optimise the statistical sensitivity to γ, as described in ref.
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