CLIMB | Challenging the Standard Model with suppressed b to d l+l- decays

Summary
The Standard Model (SM) of particle physics is one of the most complete theories in science with a hugely successful predicting power. However, it is unable to explain critical observed phenomena, such as the dominance of matter over antimatter in the universe, and thus needs to be extended. Rare decays of b quarks to an s quark and two leptons (b to sll) are very sensitive to the existence of New Physics (NP). Recent measurements of their properties show intriguing deviations with respect to SM predictions that could be the first clear hint of NP in decades. In this project, I will explore the related and even more suppressed b-quark decays to a d quark and two leptons (b to dll), which are so far poorly known and will shed light on the type on NP that could explain the observed discrepancies. For this purpose, my team will develop innovative analysis tools and exploit the uniquely large sample of b hadrons from the LHCb experiment.

The CLIMB project will address two specific questions: are the deviations observed in b to sll decays also present in b to dll transitions? Are there new sources of matter-antimatter asymmetry beyond the SM in b to dll processes?
The first will be addressed by measuring differential decay probabilities and lepton universality ratios in b to dll decays for the first time.
In the SM, these transitions are related by the quark-mixing matrix, the hierarchy of which is not fully understood. NP models aim to provide an explanation for the structure observed in nature. Knowing the properties of b to dll decays precisely is a critical input in this endeavour.
The second question will be answered by measuring matter-antimatter asymmetries in b to dll decays with unprecedented precision, providing very strong constraints to NP models predicting an enhanced quantity. The main challenge of this programme lies in the study of very suppressed decays. Innovative reconstruction and selection techniques will be developed to access them.
Unfold all
/
Fold all
More information & hyperlinks
Web resources: https://cordis.europa.eu/project/id/101077940
Start date: 01-04-2023
End date: 31-03-2028
Total budget - Public funding: 1 622 273,00 Euro - 1 622 273,00 Euro
Cordis data

Original description

The Standard Model (SM) of particle physics is one of the most complete theories in science with a hugely successful predicting power. However, it is unable to explain critical observed phenomena, such as the dominance of matter over antimatter in the universe, and thus needs to be extended. Rare decays of b quarks to an s quark and two leptons (b to sll) are very sensitive to the existence of New Physics (NP). Recent measurements of their properties show intriguing deviations with respect to SM predictions that could be the first clear hint of NP in decades. In this project, I will explore the related and even more suppressed b-quark decays to a d quark and two leptons (b to dll), which are so far poorly known and will shed light on the type on NP that could explain the observed discrepancies. For this purpose, my team will develop innovative analysis tools and exploit the uniquely large sample of b hadrons from the LHCb experiment.

The CLIMB project will address two specific questions: are the deviations observed in b to sll decays also present in b to dll transitions? Are there new sources of matter-antimatter asymmetry beyond the SM in b to dll processes?
The first will be addressed by measuring differential decay probabilities and lepton universality ratios in b to dll decays for the first time.
In the SM, these transitions are related by the quark-mixing matrix, the hierarchy of which is not fully understood. NP models aim to provide an explanation for the structure observed in nature. Knowing the properties of b to dll decays precisely is a critical input in this endeavour.
The second question will be answered by measuring matter-antimatter asymmetries in b to dll decays with unprecedented precision, providing very strong constraints to NP models predicting an enhanced quantity. The main challenge of this programme lies in the study of very suppressed decays. Innovative reconstruction and selection techniques will be developed to access them.

Status

SIGNED

Call topic

ERC-2022-STG

Update Date

09-02-2023
Images
No images available.
Geographical location(s)
Structured mapping
Unfold all
/
Fold all
Horizon Europe
HORIZON.1 Excellent Science
HORIZON.1.1 European Research Council (ERC)
HORIZON.1.1.0 Cross-cutting call topics
ERC-2022-STG ERC STARTING GRANTS
HORIZON.1.1.1 Frontier science
ERC-2022-STG ERC STARTING GRANTS