Dispersive and Absorptive CP Violation in $D^0- \overline{D^0}$ Mixing

CP violation (CPV) in D0-D¯0 mixing is described in terms of the dispersive and absorptive “weak phases” ϕfM and ϕfΓ. They parametrize CPV originating from the interference of D0 decays with and without dispersive mixing, and with and without absorptive mixing, respectively, for CP conjugate hadronic final states f, f¯. These are distinct and separately measurable effects. For CP eigenstate final states, indirect CPV only depends on ϕfM (dispersive CPV), whereas ϕfΓ (absorptive CPV) can only be probed with non-CP eigenstate final states. Measurements of the final state dependent phases ϕfM, ϕfΓ determine the intrinsic dispersive and absorptive mixing phases ϕ2M and ϕ2Γ. The latter are the arguments of the dispersive and absorptive mixing amplitudes M12 and Γ12, relative to their dominant (ΔU=2) U-spin components. The intrinsic phases are experimentally accessible due to approximate universality: in the SM, and in extensions with negligible new CPV phases in Cabibbo favored/doubly Cabibbo suppressed (CF/DCS) decays, the deviation of ϕfM,Γ from ϕ2M,Γ is negligible in CF/DCS decays D0→K±X, and below 10% in CF/DCS decays D0→KS,LX (up to precisely known O(εK) corrections). In singly Cabibbo suppressed (SCS) decays, QCD pollution enters at O(ε) in U-spin breaking and can be significant, but is O(ε2) in the average over f=K+K-, π+π-. SM estimates yield ϕ2M,ϕ2Γ=O(0.2%). A fit to current data allows O(10) larger phases at 2σ, from new physics. A fit based on naively extrapolated experimental precision suggests that sensitivity to ϕ2M and ϕ2Γ in the SM may be achieved at the LHCb Phase II upgrade.