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The European physical journal. C, Particles and fields, 2020-03, Vol.80 (3), p.1-27, Article 252
Ort / Verlag
Berlin/Heidelberg: Springer Berlin Heidelberg
Erscheinungsjahr
2020
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Following the updated measurement of the lepton flavour universality (LFU) ratio
R
K
in
B
→
K
ℓ
ℓ
decays by LHCb, as well as a number of further measurements, e.g.
R
K
∗
by Belle and
B
s
→
μ
μ
by ATLAS, we analyse the global status of new physics in
b
→
s
transitions in the weak effective theory at the
b
-quark scale, in the Standard Model effective theory above the electroweak scale, and in simplified models of new physics. We find that the data continues to strongly prefer a solution with new physics in semi-leptonic Wilson coefficients. A purely muonic contribution to the combination
C
9
=
-
C
10
, well suited to UV-complete interpretations, is now favoured with respect to a muonic contribution to
C
9
only. An even better fit is obtained by allowing an additional LFU shift in
C
9
. Such a shift can be renormalization-group induced from four-fermion operators above the electroweak scale, in particular from semi-tauonic operators, able to account for the potential discrepancies in
b
→
c
transitions. This scenario is naturally realized in the simplified
U
1
leptoquark model. We also analyse simplified models where a LFU effect in
b
→
s
ℓ
ℓ
is induced radiatively from four-quark operators and show that such a setup is on the brink of exclusion by LHC di-jet resonance searches.