What is the scale of new physics behind the B-flavour anomalies?
By Luca Di Luzio, Marco Nardecchia. 2017
157 citations recorded by the source corpus.
Motivated by the recent hints of lepton flavour non-universality in B-meson semi-leptonic decays, we study the constraints of perturbative unitarity on the new physics interpretation of the anomalies in $$b \rightarrow c \ell \bar{\nu }$$b→cℓν¯ and $$b \rightarrow s \ell \bar{\ell }$$b→sℓℓ¯ transitions. Within an effective field theory approach we find that $$2 \rightarrow 2$$2→2 fermion scattering amplitudes saturate the unitarity bound below 9 and 80 TeV, respectively for $$b \rightarrow c \ell \bar{\nu }$$b→cℓν¯ and $$b \rightarrow s \ell \bar{\ell }$$b→sℓℓ¯ transitions. Stronger bounds, up to few TeV, are obtained when the leading effective operators are oriented in the direction of the third generation, as suggested by flavour models. We finally address unitarity constraints on simplified models explaining the anomalies and show that the new physics interpretation is ruled out in a class of perturbative realizations.
View Paper: https://www.semanticscholar.org/paper/1668be68456cab81b42f6df4b8915ef0eb11d06b
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
- L. Luzio
- Ediotors A. Cerri
- L. Calibbi
- Maurizio Giannotti
- E. Nardi
- Vladimir Vava Gligorov
- Luca Visinelli
- S. Malvezzi
Citations in the corpus
- Charged Lepton Flavour Violation: An Experimental and Theoretical Introduction (2017, background): “For a detailed recent discussion on the new-physics scales hinted at by these anomalies see [217].”
- Opportunities in Flavour Physics at the HL-LHC and HE-LHC (2018, background): “Perturbative unitarity sets an upper bound on the energy scale below which new dynamics need to appear [1483].”
- The landscape of QCD axion models (2020, background): “Ignoring running effects, which would make the bound even stronger, and taking into account group theory factors [113, 114], one gets [115]: y t,b < √ 16π/3 (the strongest bound comes from the channel QLuR(dR) → QLuR(dR), with the initial and final states prepared into SU(3)c singlets).”