Abstract
The first measurements of the forward-backward asymmetry of the dimuon pair (A_{FB}), the triple-product asymmetry (A_{2ϕ}), and the charge-parity-conjugation asymmetry (A_{CP}), in D^{0}→π^{+}π^{-}μ^{+}μ^{-} and D^{0}→K^{+}K^{-}μ^{+}μ^{-} decays are reported. They are performed using data from proton-proton collisions collected with the LHCb experiment from 2011 to 2016, corresponding to a total integrated luminosity of 5 fb^{-1}. The asymmetries are measured to be A_{FB}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(3.3±3.7±0.6)%, A_{2ϕ}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(-0.6±3.7±0.6)%, A_{CP}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(4.9±3.8±0.7)%, A_{FB}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(0±11±2)%, A_{2ϕ}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(9±11±1)%, A_{CP}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(0±11±2)%, where the first uncertainty is statistical and the second systematic. The asymmetries are also measured as a function of the dimuon invariant mass. The results are consistent with the standard model predictions.
Highlights
Decays of charm hadrons into final states containing muon pairs may proceed via the so-called short-distance c → uμþμ− flavor-changing neutral-current process
In the standard model (SM) such process can only occur through electroweak loop transitions that are highly suppressed by the Glashow-Iliopoulos-Maiani mechanism [1]
(charge-conjugated decays are implied unless stated otherwise), where h is either a pion or a kaon, are described by five independent kinematic variables (Fig. 1): the dimuon invariant mass, mðμþμ−Þ, the dihadron invariant mass, mðhþh−Þ. the angle θμ between the μþ (μ−) direction and the direction opposite to the D0 (D 0) meson in the dimuon rest frame, the angle θh between the hþ (h−) direction and the direction opposite to the D0 (D 0) meson in the dihadron rest frame, and the angle φ between the two planes formed by the dimuon and the dihadron systems in the rest frame of the D0 meson
Summary
Decays of charm hadrons into final states containing muon pairs may proceed via the so-called short-distance c → uμþμ− flavor-changing neutral-current process.
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