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A new B-flavour anomaly in $B_{d,s} \to K^{*0}\overline{K}^{*0}$: anatomy and interpretation{


Algueró, Marcel; Crivellin, Andreas; Descotes-Genon, Sébastien; Matias, Joaquim; Novoa-Brunet, Martín (2021). A new B-flavour anomaly in $B_{d,s} \to K^{*0}\overline{K}^{*0}$: anatomy and interpretation{. Journal of High Energy Physics, 2021:66.

Abstract

In the context of the recently measured non-leptonic decays Bd → K∗0K¯¯¯¯¯∗0 and Bs → K∗0K¯¯¯¯¯∗0 we analyse the anatomy of the LVV observable that compares the longitudinal components of Bs → VV and Bd → VV decays. This observable is cleaner than the longitudinal polarisation fraction as it is afflicted only at subleading order in a 1/mb expansion by the theoretical uncertainties arising in the transverse components entering the polarisation fraction. Focusing on the particular case of Bd → K∗0K¯¯¯¯¯∗0 and Bs → K∗0K¯¯¯¯¯∗0, we discuss the main sources of hadronic uncertainty in the SM. We find for the SM prediction LK∗K¯¯¯¯¯∗=19.5+9.3−6.8, which implies a 2.6σ 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 C4 and C8g 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 C4 (Kaluza-Klein gluon) or in C8g, with a significant amount of fine tuning, but possible connections to the b → sℓℓ anomalies.

Abstract

In the context of the recently measured non-leptonic decays Bd → K∗0K¯¯¯¯¯∗0 and Bs → K∗0K¯¯¯¯¯∗0 we analyse the anatomy of the LVV observable that compares the longitudinal components of Bs → VV and Bd → VV decays. This observable is cleaner than the longitudinal polarisation fraction as it is afflicted only at subleading order in a 1/mb expansion by the theoretical uncertainties arising in the transverse components entering the polarisation fraction. Focusing on the particular case of Bd → K∗0K¯¯¯¯¯∗0 and Bs → K∗0K¯¯¯¯¯∗0, we discuss the main sources of hadronic uncertainty in the SM. We find for the SM prediction LK∗K¯¯¯¯¯∗=19.5+9.3−6.8, which implies a 2.6σ 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 C4 and C8g 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 C4 (Kaluza-Klein gluon) or in C8g, with a significant amount of fine tuning, but possible connections to the b → sℓℓ anomalies.

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Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Scopus Subject Areas:Physical Sciences > Nuclear and High Energy Physics
Uncontrolled Keywords:Nuclear and High Energy Physics
Language:English
Date:1 April 2021
Deposited On:29 Apr 2021 14:50
Last Modified:16 Mar 2024 04:44
Publisher:Springer
ISSN:1029-8479
OA Status:Gold
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1007/jhep04(2021)066
  • Content: Published Version
  • Licence: Creative Commons: Attribution 4.0 International (CC BY 4.0)