Study of some (non-)conventional mesons in the framework of effective models

TL;DR

This study uses effective quantum field theory models to analyze the nature of certain mesons, revealing some as dynamically generated states or spurious enhancements rather than genuine particles.

Contribution

It demonstrates how effective models can identify the nature of mesons as companion poles or artifacts, clarifying the status of several controversial states.

Findings

K*_0(700) is a companion pole of K*_0(1430)

X(3872) is a virtual companion pole of χ_{c1}(2P)

Y(4008) is a spurious enhancement, not a real state

Abstract

The main aim of our study is to understand the nature of some conventional and non-conventional mesonic states by applying effective QFT models. We start from the relativistic Lagrangians containing a unique $q\bar{q}$ seed state which is strongly coupled to the low-masses decay products of the original state. We find out that some states may appear as a dynamically generated companion poles of the heavier $q\bar{q}$ mesons. In particular we show that $K^*_0(700)$ is a companion pole of the well-known $K^*_0(1430)$ resonance, $X(3872)$ emerges as a (virtual) companion pole of $\chi_{c1}(2P)$, and the puzzling $Y(4008)$ is not a real state, but a spurious enhancement which appears when studying the state $\psi(4040)$.