“A new B-flavour anomaly in Bd,s->K0 anti-K0: anatomy and interpretation” by M. Algueró, A. Crivellin, S. Descotes-Genon, J. Matias and M. Novoa-Brunet. has been submitted to the arXiv.

We identify a new anomaly in an observable that we called L, constructed upon the longitudinal amplitudes of the non-leptonic decays Bd->K0* anti K0* versus Bs->K0* anti K0*. This observable is protected from leading order infrared divergences in hard-scattering and weak annihilation diagrams and exihibits a 2.6 sigma tension with data.

We establish a parallelism with RK of semileptonic B decays interchanging leptons by quarks and we identify the dominant Wilson coefficient in an EFT approach that could explain the anomaly with a 25% NP contribution.