Navigation auf


Physik-Institut Group of Gino Isidori


Flavor Anomalies and the origin of the Yukawa couplings


Advanced Grant project funded by the Eupean Research Council  [09.2019 - 08.2024] 



Recent experimental results in flavor physics exhibit deviations from the Standard Model predictions that are growing with time, both as far as statistical significance and as far as internal consistency. Understanding the origin of this phenomenon, the so-called “flavor anomalies”, is of paramount importance for a deeper understanding of fundamental interactions. As recently shown by the G. Isidori and collaborators, this phenomenon is likely to be intimately related to the long-standing “flavor problem”, or the origin of the hierarchical pattern of quark and lepton mass matrices observed in Nature. The goal of this ERC project FLAY is to shed light on both these issues, providing a solution to old and recent puzzles in flavor physics. We address these questions via an original bottom-up approach, based on Effective Field Theory methods and simplified models, combined with new top-down ideas about the ultraviolet completion of the Standard Model. On the phenomenological side, the proposed bottom-up approach will allow us to exploit with the highest accuracy all the available and expected experimental data. It will allow us to take into account both low- and high-energy observables, as well as both quark and lepton sectors. These results will constitute the basis for the theoretical investigation of a new class of Standard Model extensions not considered so far. The latter are based on new ideas, such as flavor non-universal gauge interactions, that imply a change of paradigm in theoretical high-energy physics: the origin of the flavor hierarchies plays a central role in revealing the ultraviolet completion of the Standard Model. Combining a bottom-up approach to flavor-physics data with top-down ideas on the origin of the flavor hierarchies, this project has the potential to lead to a major advancement in fundamental physics.

Key publications



  • With or without U(2)? Probing non-standard flavor and helicity structures in semileptonic B decays 
    [J. Fuentes-Martín, G. Isidori, J. Pagès, K. Yamamoto] arxiv:1909.02519
  • Vector leptoquarks beyond tree level. I 
    [J. Fuentes-Martín, G. Isidori, M. König, N. Selimović] arxiv:1910.13474



  • Hunting for B → K tau+ tau- imprints on the B → K mu+ mu- dimuon spectrum
    [C. Cornella, G. Isidori, M. König, S. Liechti, P. Owen, N. Serra] arxiv:2001.04470
  • Third-family quark-lepton unification with a fundamental composite Higgs  
    [J. Fuentes-Martín, P. Stangl] arxiv:2004.11376
  • Flavour symmetries in the SMEFT
    [D.A. Faroughy, G. Isidori, F. Wilsch, K. Yamamoto] arxiv:2005.05366
  • Vector leptoquarks beyond tree level. II
    [J. Fuentes-Martín, G. Isidori, M. König, N. Selimović] arxiv:2006.16250
  • Optimized lepton universality tests in B → V ℓ+ ℓ- decays
    [G. Isidori, O. Sumensari] arxiv:2007.08481
  • QED corrections in  B → K ℓ+ ℓ- at the double-differential level
    [G. Isidori, S. Nabeebaccus, R. Zwicky] arxiv:2009.00929
  • Vector leptoquarks beyond tree level. III
    [J. Fuentes-Martín, G. Isidori, M. König, N. Selimović] arxiv:2009.11296
  • Stability of the Higgs sector in a flavor-inspired multi-scale model
    [L. Allwicher, G. Isidori, A.E. Thomsen] arxiv:2011.01946
  • Lepton-quark fusion at Hadron colliders, precisely
    [A. Greljo,  N. Selimovic] arxiv:2012.02092
  • Flavor non-universal Pati-Salam unification and neutrino masses
    [J. Fuentes-Martín, G. Isidori, J. Pagès, B.A. Stefanek]  arxiv:2012.10492



  • The LFU ratio Rπ in the Standard Model and beyond
    [M. Bordone, C. Cornella, G. Isidori, M. König] arxiv:2101.11626
  • Reading the footprints of the B-meson flavor anomalies
    [C. Cornella, D. A. Faroughy, J. Fuentes-Martín, G. Isidori, M. Neubert] arxiv:2103.16558
  • On the significance of new physics in b → s ℓ+ ℓ- decays
    [G. Isidori, D. Lancierini,  P. Owen, N. Serra]
  • LFU violations in leptonic tau decays and B-physics anomalies
    [L. Allwicher, G. Isidori, N. Selimovic] arxiv:2109.03833
  • Flavour alignment of New Physics in light of the (g − 2)μ anomaly
    [G. Isidori, J. Pagès, F. Wilsch] arxiv:2111.13724
  • A general effective field theory description of b → s ℓ+ ℓ- lepton universality ratios
    [G. Isidori, D. Lancierini, A. Mathad, P. Owen, N. Serra, R. S. Coutinho] arxiv:2110.09882



  • Flavor hierarchies, flavor anomalies, and Higgs mass from a warped extra dimension
    [J. Fuentes-Martin, G. Isidori, J. M. Lizana, N. Selimovic, B.A. Stefanek] arxiv:2203.01952

Weiterführende Informationen

Hopes and worries on B-physics anomalies

How particle physics works I

More about How particle physics works I

Hopes and Worries on B-physics Anomalies


Theoreticians end experimental physicists are closely collaborating to find out if the anomalies observed by the experiment LHCb can be confirmed, and in case how this would change the Standard Model. But what are these anomalies? And how is the Physicists community discussing about them? 

Hopes and worries on B-physics anomalies

How Particle Physics works II

More about How Particle Physics works II

The New Analysis 


Follow-up video about new results released in Spring 2019.

The Anomalies Strike Back

How particle physics works III

More about How particle physics works III

The Anomalies Strike Back


In Spring 2021 new results released by LHCb strengthened the significance of the anomalies