2026/07/22 by LHCb collaboration, R. Aaij, M. Abdelfatah +1106 · 1 voice
#hep-ex
A search for charge-parity (C P) violation in the Cabibbo-suppressed D+ → ϕπ+ decay is presented, using proton-proton collision data corresponding to an integrated luminosity of 6 fb-1, collected at a centre-of-mass energy of 13 TeV with the LHCb detector during Run 2. An abundant sample of D+ → K\rm S0 π+ decays is employed to correct for asymmetries arising from the production of the charmed meson and from detection effects associated with the charged pion accompanying the ϕ meson. Asymmetries induced by interference of multiple processes, such as neutral kaon mixing, regeneration of neutral kaons, and interference between the Cabibbo-favoured D+ → K0 π+ and the doubly Cabibbo-suppressed D+ → K0 π+ decay, are subtracted. The direct C P asymmetry in the D+ → ϕπ+ decay is measured to be aC P(D+ → ϕπ+) = (0.1 ± 4.9 (stat) ± 2.4 (syst) )× 10-4. For the first time at a hadron collider, the modulus of the ratio and the relative strong phase of the D+ → K0 π+ to D+ → K0 π+ decay amplitudes are also investigated. Two-dimensional confidence intervals are reported for these parameters.