New Theory Paper

November 18, 2020

Theory Division

“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.

Latest Group News

In the Media

Latest and Fermilab and LHCb results in the media

April 21, 2021

Two new articles about the latest Fermilab g-2 Experiment and LHCb results quoting IFAE researchers published in El Mundo and El Pais

In the Media

Latest Fermilab reuslts at diari ARA

April 9, 2021

Pere Masjuan is quoted in an article in the diari Ara about the lastest Fermilab’s Muon g-2 experiment results.

New experimental results

LHCb results strengthen hints of a violation of lepton flavour universality

April 7, 2021

LHCb has overcome the 3 sigma barrier in the tension between the measurement of the observable RK and the prediction of the SM, reaching 3.1 sigmas. This observable tests the universality (or not) of leptonic flavor. The SM predicts a value of 1 very accurately for this observable.