Excited Scalar and Pseudoscalar Mesons in the Extended Linear Sigma Model

TL;DR

This paper investigates the masses and decays of excited scalar and pseudoscalar mesons within the Extended Linear Sigma Model, focusing on the potential identification of certain resonances as excited quarkonium states.

Contribution

It introduces an analysis of excited scalar and pseudoscalar mesons in the eLSM, proposing interpretations for the $f_0(1790)$ and $a_0(1950)$ resonances as excited quarkonium states.

Findings

Supports the interpretation of $f_0(1790)$ as an excited scalar quarkonium.

Suggests $a_0(1950)$ may also be an excited scalar state.

Identifies tensions in simultaneously interpreting certain pseudoscalar mesons as excited states.

Abstract

We present an in-depth study of masses and decays of excited scalar and pseudoscalar $\bar{q}q$ states in the Extended Linear Sigma Model (eLSM). The model also contains ground-state scalar, pseudoscalar, vector and axial-vector mesons. The main objective is to study the consequences of the hypothesis that the $f_0(1790)$ resonance, observed a decade ago by the BES Collaboration and recently by LHCb, represents an excited scalar quarkonium. In addition we also analyse the possibility that the new $a_0(1950)$ resonance, observed recently by BABAR, may also be an excited scalar state. Both hypotheses receive justification in our approach although there appears to be some tension between the simultaneous interpretation of $f_0(1790)$/$a_0(1950)$ and pseudoscalar mesons $\eta(1295)$, $\pi(1300)$, $\eta(1440)$ and $K(1460)$ as excited $\bar{q}q$ states.