A model-independent Dalitz plot analysis of B ± → D K ± with D → K S 0 h + h ? ( h = π , K ) decays and constraints on the CKM angle γ

摘要

A binned Dalitz plot analysis of B ± → D K ± decays, with D → K S 0 π + π ? and D → K S 0 K + K ? , is performed to measure the CP -violating observables x ± and y ± which are sensitive to the CKM angle γ . The analysis exploits 1.0 fb ? 1 of data collected by the LHCb experiment. The study makes no model-based assumption on the variation of the strong phase of the D decay amplitude over the Dalitz plot, but uses measurements of this quantity from CLEO-c as input. The values of the parameters are found to be x ? = ( 0.0 ± 4.3 ± 1.5 ± 0.6 ) × 10 ? 2 , y ? = ( 2.7 ± 5.2 ± 0.8 ± 2.3 ) × 10 ? 2 , x + = ( ? 10.3 ± 4.5 ± 1.8 ± 1.4 ) × 10 ? 2 and y + = ( ? 0.9 ± 3.7 ± 0.8 ± 3.0 ) × 10 ? 2 . The first, second, and third uncertainties are the statistical, the experimental systematic, and the error associated with the precision of the strong-phase parameters measured at CLEO-c, respectively. These results correspond to γ = ( 44 ? 38 + 43 ) ° , with a second solution at γ → γ + 180 ° , and r B = 0.07 ± 0.04 , where r B is the ratio between the suppressed and favoured B decay amplitudes.