Speaker: Daniele Lombardo (Sapienza Roma Univ.)

Up to now, bounds on the axion-up-charm axial coupling, kA, come only from the baryonic decay Lambda_c -> p a and from D-anti D mixing, which are both affected by large theoretical uncertainties. I will show a novel procedure to infer new constraints on this coupling from D0-meson decays with an axion in the final state. In particular, I will discuss how to compute the differential decay width of the BSM process D0 -> pi pi a and to find a new constraint on  kA via a sensitivity study. In particular, I will focus on the treatment of the form factors appearing in the hadronic matrix element associated with this transition, which can be directly extracted from measurements concerning semi-leptonic four-body D+-meson decays. All these inputs also produce a Dalitz plot, giving important information for future dedicated experimental searches. In conclusion, I will discuss how further constraints on kA$ may be obtained from other complementary decay channels, as for instance the D0 -> K+ K- a$ transition, and from information coming from astrophysics, such as e.g. the cooling of supernovae.