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T: Fachverband Teilchenphysik

T 15: Flavourphysik (Theorie) II

T 15.2: Vortrag

Freitag, 1. April 2011, 14:15–14:30, 30.23: 3-1

D⁰ mixing and CP violation — •Markus Bobrowski¹ and Alexander Lenz² — ¹Karlsruher Institut für Technologie (KIT), Institut für Theoretische Teilchenphysik — ²Universität Regensburg, Institut für Theoretische Physik

We report the results of a recent study on D⁰–D⁰ mixing and argue that currently a CP violating weak phase of the order of some per mille can not be excluded in the Standard Model. Our work relies on a short-distance analysis of the Δ C=2 Hamiltonian, using the framework of Heavy Quark Expansion (HQE), an expansion in powers of the inverse charm quark mass. We demonstrate that, as expected, the dominant contribution is related to effects of SU(3) flavour symmetry breaking present in higher orders of the HQE: they appear for the first time in meson-antimeson transitions with an intermediate state coupling to the sea quark background of the meson, associated with operators of dimension 10 and 12. A factorisation approach is used to simplify the operator basis. Due to a lifting of GIM suppression by one power of m_s/m_c, the contribution to y=ΔΓ/2Γ is found to exceed that of the formally leading dimension six by a factor close to ten.