https://doi.org/10.1140/epja/s10050-020-00064-5
Regular Article –Theoretical Physics
A study of power suppressed contributions in 
decay
Petersburg Nuclear Physics Institute, 188300, Gatchina, Russia
Received:
14
October
2019
Accepted:
21
December
2019
Published online:
19
February
2020
The power suppressed amplitude which describes the Pauli (
) coupling in the decay is calculated within the effective field theory framework. It is shown that at the leading-order approximation this contribution is factorisable and the overlap with the hadronic final state can be described by collinear matrix elements. The obtained contribution depends on the nucleon light-cone distribution amplitudes of twist-3 and twist-4. This result is used for a qualitative phenomenological analysis of existing data for decay: branching ratio and the angular distribution in the cross section 
. It is found that the power corrections provide a large numerical effect.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020
