Measurement of Angular and CP Asymmetries in D^0→π^+π^-μ^+μ^- and D^0→K^+K^-μ^+μ^- Decays

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.