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QED factorization for eXclusive semi-leptonic B-meson decays

Project description

Study sheds new light on leptonic B decays

Exclusive semi-leptonic B decays are processes where a B meson decays into a final state consisting of a lighter meson and a lepton-neutrino pair. These decays are crucial for measuring fundamental parameters of the standard model and searching for new particles and interactions. Recent experimental tensions with standard model predictions highlight the need for rigorous studies. Funded by the Marie Skłodowska-Curie Actions programme, the QED4X project aims to investigate structure-dependent electromagnetic corrections in these decays using effective field theory and factorisation methods. The research will focus on how photon couplings affect decay rates and angular distributions, incorporating novel hadronic parameters to improve precision. QED4X will develop factorisation theorems for charged and neutral-current semi-leptonic transitions, address endpoint singularities and develop a collinear-photon treatment for electronic channels.

Objective

Exclusive semi-leptonic B decays provide an important laboratory for measuring fundamental parameters of the Standard Model (SM), or to search for yet unknown particles and interactions. Various tensions between experimental measurements and SM predictions have been guiding the theoretical efforts over the past years.

To draw reliable conclusions from the anticipated experimental high-precision data for such decays in the coming years, requires a rigorous study of sub-leading corrections that have been neglected so far. With the proposed action, the researcher aims to investigate the impact of so-called structure-dependent electromagnetic corrections to kinematic distributions in semi-leptonic B decays, using modern Effective Field Theory and factorization methods.

A systematic study of QED corrections along these lines is a relatively new field of research, and in certain cases revealed surprising enhancement mechanisms not captured in a pointlike-meson description. An analysis of these effects in semi-leptonic transitions at the differential level is ambitious, and phenomenologically interesting. Photon couplings between the charged leptons and the meson constituents might lead to enhanced effects in rates or angular distributions. Uncertainties from novel hadronic parameters must be added to clean ratios with reduced hadronic uncertainties.

Conceptually, factorization is achieved using of Soft-Collinear Effective Theory and Heavy-Quark Effective Theory. The analysis of these decay amplitudes require modern sub-leading power techniques to deal with technical difficulties such as endpoint singularities.

The action is subdivided into four work-packages (WP): Factorization theorems for charged and neutral-current semi-leptonic transitions are derived in WP1 and WP2, respectively. Novel concepts regarding the treatment of endpoint-singularities are developed in WP3, and WP4 aims at a collinear-photon inclusive 'jet-like' treatment of electronic channels.

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Coordinator

ORGANISATION EUROPEENNE POUR LA RECHERCHE NUCLEAIRE
Net EU contribution
€ 226 629,12
Address
ESPLANADE DES PARTICULES 1 PARCELLE 11482 DE MEYRIN BATIMENT CADASTRAL 1046
1211 Meyrin
Switzerland

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Region
Schweiz/Suisse/Svizzera Région lémanique Genève
Activity type
Research Organisations
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Total cost
No data