Failure of Breit-Wigner and success of dispersive descriptions of the τ? → K?ηντ decays

14th Mexican Workshop on Particles and Fields

Roig, Pablo^1

Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, México D.F.

01000, Mexico^1

关键词: Active field;    Chiral perturbation theory;    Exponentiations;    Final state interactions;    Loop functions;    Parametrizations;    Strong interaction;    Wigner approximation;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/651/1/012019/pdf
DOI  :  10.1088/1742-6596/651/1/012019

来源: IOP

【 摘 要 】

The τ¯ → K-ηντdecays have been studied using Chiral Perturbation Theory extended by including resonances as active fields. We have found that the treatment of final state interactions is crucial to provide a good description of the data. The Breit-Wigner approximation does not resum them and neglects the real part of the corresponding chiral loop functions, which violates analyticity and leads to a failure in the confrontation with the data. On the contrary, its resummation by means of an Omnès-like exponentiation of through a dispersive representation provides a successful explanation of the measurements. These results illustrate the fact that Breit-Wigner parametrizations of hadronic data, although simple and easy to handle, lack a link with the underlying strong interaction theory and should be avoided. As a result of our analysis we determine the properties of the K+(1410) resonance with a precision competitive to its traditional extraction using τ- → (Kπ)-ντ decays, albeit the much limited statistics accumulated for the τ- → K-ηντ channel. We also predict the soon discovery of the τ- → K-η0ντ decays.