2021/10/19 by Ciuchini, Marco, Fedele, Marco, Franco, Enrico +3
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2110.10126
The LHCb experiment has very recently presented new results on Lepton Universality Violation (LUV) in B → K(*) ℓ+ ℓ- decays involving KS in the final state, which strengthens the recent evidence of LUV obtained in B+ → K+ ℓ+ ℓ- decays and the previous measurements of B → K*0 ℓ+ ℓ-. While LUV observables in the Standard Model are theoretically clean, their predictions in New Physics scenarios are sensitive to the details of the hadronic dynamics, and in particular of the charming penguin contribution. In this work, we show how a conservative treatment of hadronic uncertainties is crucial not only to assess the significance of deviations from the Standard Model but also to obtain a conservative picture of the New Physics responsible for LUV. Adopting a very general parameterization of charming penguins, we find that: i) current data hint at a sizable q2 and helicity dependence of charm loop amplitudes; ii) conservative NP solutions to B anomalies favour a left-handed or an axial lepton coupling rather than a vector one.