Dalitz plot studies of D0 to K0S pi+ pi- decays

TL;DR

This paper analyzes D0 to K0S pi+ pi- decays using a quasi two-body QCD factorization approach, incorporating various amplitudes and form factors constrained by experimental data, to reproduce Dalitz plot distributions.

Contribution

It introduces a comprehensive model including annihilation and suppressed amplitudes, constrained form factors, and a minimization procedure to fit experimental Dalitz plot data.

Findings

Model reproduces Dalitz plot distributions accurately.

Branching fractions align with Belle data.

Inclusion of multiple amplitudes improves fit quality.

Abstract

The availaible data on the D0 to K0S pi+ pi- decays are analysed in the framework of the quasi two-body QCD factorization approximation. The annihilation, via W-exchange, amplitudes are added to the weak-decay tree amplitudes. The doubly Cabibbo suppressed parts of the amplitudes are also considered. The strong interactions between the kaon-pion and pion-pion pairs in the S-, P- and D-final states are described in terms of the corresponding form factors. The kaon-pion or pion-pion scalar and vector form factors are constrained by other experimental data. Unitarity, analyticity and chiral symmetry are also used to obtain their functional forms. We go through a minimization procedure to reproduce the K0S pi-, K0S pi+ and pi+ pi- effective mass projections of the Dalitz plot distributions. The large number (27) of non-zero amplitudes leads to a large number of parameters. The resulting model distributions and branching fractions are compared to the accurate Belle Collaboration data.