A new B-flavour anomaly in Bd,s → K∗0K¯∗0: anatomy and interpretation

• Published in: The journal of high energy physics Vol. 2021; no. 4
• Main Authors: Algueró, Marcel, Crivellin, Andreas, Descotes-Genon, Sébastien, Matias, Joaquim, Novoa-Brunet, Martín
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 08-04-2021; Springer Nature B.V
• Subjects: Anatomy; Anomalies; Classical and Quantum Gravitation; Decay; Elementary Particles; Flavors; Gluons; High energy physics; Leptons; Physics; Physics and Astronomy; Polarization; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Quarks; Regular Article - Theoretical Physics; Relativity Theory; String Theory; Uncertainty; Heavy Quark Physics; Effective Field Theories
• ISSN: 1029-8479
• DOI: 10.1007/JHEP04(2021)066

A
bstract
In the context of the recently measured non-leptonic decays
B
d
→
K
∗
0
K
¯
∗
0
and
B
s
→
K
∗
0
K
¯
∗
0
we analyse the anatomy of the
L
VV
observable that compares the longitudinal components of
B
s
→
VV
and
B
d
→
VV
decays. This observable is cleaner than the longitudinal polarisation fraction as it is afflicted only at subleading order in a 1
/m
b
expansion by the theoretical uncertainties arising in the transverse components entering the polarisation fraction. Focusing on the particular case of
B
d
→
K
∗
0
K
¯
∗
0
and
B
s
→
K
∗
0
K
¯
∗
0
, we discuss the main sources of hadronic uncertainty in the SM. We find for the SM prediction
L
K
∗
K
¯
∗
=
19.5
−
6.8
+
9.3
, which implies a 2
.
6
σ
tension with respect to the most recent data, pointing to a deficit in the
b
→
s
transition of the non-leptonic decay versus the corresponding
b
→
d
transition. We discuss possible New Physics explanations for this deviation, first at the level of the Weak Effective Theory and we identify that the two Wilson coefficients
C
4
and
C
8
g
can play a central role in explaining this anomaly. Finally, we briefly explore two different simplified New Physics models which can explain the anomaly through a contribution either in
C
4
(Kaluza-Klein gluon) or in
C
8
g
, with a significant amount of fine tuning, but possible connections to the
b
→
s
ℓℓ anomalies.