Kpi form factors and final state interactions in D+ --> K- pi+ pi+ decays

TL;DR

This paper develops a model for the decay D+ --> K- pi+ pi+ that incorporates form factors and final state interactions, accurately matching experimental data with minimal parameters.

Contribution

It introduces a novel decay model using scalar and vector form factors constrained by fundamental principles, with only two free parameters fixed by experimental data.

Findings

Model reproduces the Dalitz plot and Kpi spectra accurately.

S-wave phase and modulus agree with experimental results up to 1.55 GeV.

Total branching ratio due to S-wave interactions is well matched.

Abstract

We present a model for the decay D+ --> K- pi+ pi+. The weak interaction part of this reaction is described using the effective weak Hamiltonian in the factorisation approach. Hadronic final state interactions are taken into account through the Kpi scalar and vector form factors fulfilling analyticity, unitarity and chiral symmetry constraints. The model has only two free parameters that are fixed from experimental branching ratios. We show that the modulus and phase of the S wave thus obtained agree nicely with experiment up to 1.55 GeV. We perform Monte Carlo simulations to compare the predicted Dalitz plot with experimental analyses. Allowing for a global phase difference between the S and P waves of -65 degrees, the Dalitz plot of the D+ --> K- pi+ pi+ decay, the Kpi invariant mass spectra and the total branching ratio due to S-wave interactions are well reproduced.