Paolo Franchini

Abstract:

We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating angle γ through a Dalitz plot analysis of neutral D-meson decays to KS0π⁺π^- and KS0K⁺K^- produced in the processes B^*→DK^*, B ^*→D^*K^* with D ^*→Dπ0, Dγ, and B^*→DK ^** with K^{* *}→KS0π^*, using 468 million BB̄ pairs collected by the BABAR detector at the PEP-II asymmetric-energy e ⁺e^- collider at SLAC. We measure γ= (68±14±4±3)° (modulo 180°), where the first error is statistical, the second is the experimental systematic uncertainty, and the third reflects the uncertainty in the description of the neutral D decay amplitudes. This result is inconsistent with γ=0 (no direct CP violation) with a significance of 3.5 standard deviations. © 2010 The American Physical Society.

Abstract:

We report a direct measurement of D0-D^̄0 mixing parameters through a time-dependent amplitude analysis of the Dalitz plots of D0→KS0π⁺π^- and, for the first time, D0→KS0K⁺K^- decays. The low-momentum pion πs+ in the decay D^*+→D0πs+ identifies the flavor of the neutral D meson at its production. Using 468.5fb^-1 of e ⁺e^- colliding-beam data recorded near √s=10.6GeV by the BABAR detector at the PEP-II asymmetric-energy collider at SLAC, we measure the mixing parameters x=[1.6±2.3(stat)±1.2(syst)±0.8(model) ]×10^-3, and y=[5.7±2.0(stat)±1.3(syst)±0. 7(model)]×10^-3. These results provide the best measurement to date of x and y. The knowledge of the value of x, in particular, is crucial for understanding the origin of mixing. © 2010 The American Physical Society.