Can up FCNC solve the ΔACP puzzle?

We investigate the attempt using flavor violation gauge interaction in the up sector to explain the LHCb recently observed large ΔACP (ACP(D0→K+K−)−ACP(D0→π+π−)). We study an Abelian model that only right-handed up quarks is charged under it and the 1-3 coupling is maximized. The simultaneous 1-3 2-3 mixing is realized by a quark mixing of 1-2 generation. Given the easy identification of top quark, the model can be directly tested by ΔF=1 and ΔF=2 processes at the hadron colliders as associated top production gc→tZ′ or same-sign top scattering uu→tt. The direct search bounds are still consistent with the assumption that ut and ct couplings are equal but the same-sign top scattering bound is expected to be reached very soon. However, since there is no CKM-like suppression, the corresponding parameter space for generating ΔACP is completely excluded by the D0-D¯0 mixing. We conclude that the up FCNC type models cannot explain the ΔACP while to be consistent with the D0-D¯0 mixing constraint at the same time. On the other hand, a model as SM with fourth family extension has better chance to explain the large ΔACP consistently.