Searches for CP violation in two-body charm decays

الأصل · EN

The LHCb experiment recorded data corresponding to an integrated luminosity of 3.0 fb⁻¹ during its first run of data taking. These data yield the largest samples of charmed hadrons in the world and are used to search for CP violation in the D⁰ system. Among the many measurements performed at LHCb, a measurement of the direct CP asymmetry in D⁰ → Kₛ⁰ Kₛ⁰ decays is presented and is found to be ACP(D⁰ → Kₛ⁰ Kₛ⁰) = (-2.9 ± 5.2 ± 2.2) %, where the first uncertainty is statistical and the second systematic. This represents a significant improvement in precision over the previous measurement of this parameter. Measurements of the parameter AΓ, defined as the CP asymmetry of the D⁰ effective lifetime when decaying to a CP eigenstate, are also presented. Using semi-leptonic b-hadron decays to tag the flavour of the D⁰ meson at production with the K+K- and π+π- final states yields AΓ(K+K-) = (-0.134 ± 0.077⁺⁰.⁰²⁶₋₀.₀₃₄) %, AΓ(π+π-) = (-0.092 ± 0.145⁺⁰.⁰²⁵₋₀.₀₃₃) %. Thus no evidence of direct or indirect CP violation in the D⁰ system is found, though it is tightly constrained.