Chiral loops in the isospin violating decays of D_{s1}(2460) and D*_{s0}(2317)

TL;DR

This paper investigates isospin-violating decays of positive parity mesons D_{s1}(2460) and D*_{s0}(2317) using heavy meson chiral perturbation theory, emphasizing loop contributions and decay width calculations.

Contribution

It provides a detailed analysis of loop effects and counter-term contributions in the isospin-violating decays of these mesons, offering new insights into their decay mechanisms.

Findings

Chiral loop contributions are significant in decay amplitudes.

Calculated decay widths are approximately 0.25 keV and 0.15 keV.

Sensitivity of amplitudes to coupling constants was demonstrated.

Abstract

Positive parity meson states D*_{s0}(2317) and D_{s1}(2460) have masses slightly below the DK threshold. Therefore, both states can strongly decay only into isospin violating decays D_{s1}(2460) --> Ds \pi \pi, D_{s1}(2460) --> Ds* \pi 0 and D*_{s0}(2317) --> Ds \pi 0. The pion states are having rather small energies, what makes these decays appropriate to study within heavy meson chiral perturbation theory and calculate loop contributions. The D_{s1}(2460) --> Ds \pi \pi decays occur only at the loop level. Amplitude is a result of chiral loop contributions, which then have to be finite. However, in the case of D_{s1}(2460)--> Ds* \pi 0 and D*_{s0}(2317)--> Ds \pi 0 decays, there is a tree level contribution. We find that chiral loop contributions might be important in both cases. The calculated amplitudes are sensitive on the coupling constant describing the interaction of positive and negative parity heavy meson multiplets with the light pseudoscalars. The counter-terms contributions are also present in the amplitudes D_{s1}(2460) --> Ds* \pi 0 and D*_{s0}(2317) --> Ds \pi 0. We explore experimentally known ratio of the decay widths for these two decay modes to estimate the size of counter-terms contributions. We determine decay widths for both decay modes to be Gamma (D_{s1}(2460) --> Ds \pi + \pi -) = 0.25 keV and Gamma (D_{s1}(2460) --> Ds + \pi 0 \pi 0 ) = 0.15 keV.