Hadron resonances with coexistence of different natures

TL;DR

This paper explores the coexistence and mixing of hadronic composite and elementary natures in resonances, emphasizing how interactions derived from chiral dynamics lead to diverse structures beyond the quark model.

Contribution

It provides a theoretical framework for understanding the mixing of composite and elementary hadron states using chiral dynamics, supported by previous studies and specific examples.

Findings

Interactions generate hadronic composite/molecule states.

Mixing of different hadron natures is explicitly demonstrated.

Structures beyond the conventional quark model are identified.

Abstract

We discuss coexistence/mixing of different natures of hadronic composite (molecule) and elementary (quark-intrinsic) ones in hadron resonances. The discussions here are based on our previous publications on the origin of hadron resonances \cite{Hyodo:2008xr}, exotic $\bar D$ meson-nucleons as hadronic composites containing one anti-heavy quark \cite{Yamaguchi:2011xb}, and the study of $a_1$ as a typical example to show explicitly the mixing of the two different natures \cite{Nagahiro:2011jn}. In all cases, interactions are derived from the chiral dynamics of the light flavor sector. These interactions generate in various cases hadronic composite/molecule states, serving varieties of structure beyond the conventional quark model.