Decay and structure of heavy flavour

TL;DR

This paper provides an overview of hadron physics topics, including charmed baryon decays, CP violation, new physics in neutron beta decay, Higgs decay effects, and the intrinsic charm mechanism, using various theoretical approaches.

Contribution

It introduces novel theoretical frameworks like nonlocal field operators and the nonlocal Nambu--Jona-Lasinio model derived from QCD for describing hadronic states.

Findings

Insights into CP violation via long-distance effects in rescattering.

Indications for the intrinsic charm mechanism explaining experimental discrepancies.

Application of nonlocal models to hadron structure from QCD principles.

Abstract

In accordance to the aim of the constituing meeting of the COST action CA24159 ``Structure and Spectroscopy of Hadrons Research Project'' to introduce the different groups to the action, in this talk we give an overview over the subjects dealt with by the working group in Tartu related to hadron physics. We deal with the production and the nonleptonic decays of charmed baryons in the framework of the current algebra approach in terms of tensor invariants and explain how this approach can be used to approach CP violation via long distance effects in rescattering. New physics effects can be even seen in the classical neutron beta decay, but the helicity approach used here is also useful for e.g.\ calculating first order electroweak radiative corrections to the decay of the polarised $W$ boson. Identical particle and mass effects are seen in the Higgs decay into four leptons of the same type. The second main part starts with indications for the intrinsic charm mechanism, explaining the discrepancy between the results of SELEX and LHCb. The solution offered here is valid only if one considers nonlocal field operators. The nonlocal extension of the Nambu--Jona-Lasinio model, derived directly from QCD and combined with the relativistic Faddeev approach, allows for the description of hadronic states. We conclude by presenting open questions to the action.