Study Of Light Scalar Mesons In The Three-body Decay Of D_S Meson

Our understanding of the lowest lying light scalar mesons is not yet clear,various explanations,such as molecules,tetraquarks,hybrids,ordinary mesons,exist in literature.Study on the nature of these light scalar mesons is an interesting topic in hadron physics.In recent years,many experiments,especially the BESIII Collaboration at the Beijing electron-positron collider(BEPCII),have accumulated a large amount of experimental data,which is of great importance to further study the nature of the lowest lying light scalar mesons.Based on the BESIII experiments,we investigate the nature of the light scalar mesons a0(980)and f0(980)in the three-body decays of the Ds+ meson,including the following two issues:1.We study the role of lowest lying light scalar mesons a0(980)and f0(980)in the Ds+→K+K-π+ decay process.In 2020,by using an empirical parametric form for a0(980)and f0(980),the BESⅢ Collaboration measured this process,the reported mass and width of a0(980)and f0(980)disagree with those quoted by Particle Data Group.Previously,the BABAR Collaboration also measured this process using the similar parametric form,the obtained mass and width of a0(980)and f0(980)are also inconsistent with those of Particle Data Group.Taking into account the S-wave pseudoscalar-pseudoscalar meson interactions and the contribution of the P-wave intermediate vector meson φ,we have studied the Cabibbo-favored process Ds+→K+K-π+ within the chiral unitary method.Our calculations show that the enhancement structure near the threshold in the K+K-invariant mass distribution comes mainly from the contribution of f0(980)dynamically generated by the S-wave pseudoscalar mesons interaction.Our results also imply that,in order to reasonably describe the data near the KK threshold,more complicated structure which is dynamically generated is needed.2.We study the role of f0(980)in the Ds+→π+π0π0 decay process.Recently,the BESIII Collaboration measured the decay process of Ds+→π+π0π0.In the π0π0 invariant mass distribution,one can see a clear f0(980)signal.Based on the BESIII experiment,by taking into account the contributions of f0(980)dynamically generated by the S-wave pseudoscalar mesons interaction and those of f0(1370),f2(1270),we study the decay process Ds+→π0π0π0 within the chiral unitary method.Our calculations show that a clear f0(980)signal appears in the π0π0 invariant mass distribution,which is in agreement with the experimental measurements.In conclusion,based on the BSEIII measurements,we investigate the two decay processes Ds+→K+K-π+ and Ds+→π+π0π0.Our results favor the picture of light scalar mesons a0(980)and f0(980)being the hadronic molecules,which could be useful for the further experimental investigation on these light scalar mesons.