X(2175) as a resonant state of the $\phi K \bar{K}$ system

TL;DR

This paper models the X(2175) resonance as a $ ext{phi} f_0(980)$ state formed from a three-meson system using Faddeev calculations and chiral interactions, explaining recent experimental observations.

Contribution

It introduces a Faddeev approach combined with chiral dynamics to describe the X(2175) as a three-meson resonance, providing a theoretical interpretation of experimental data.

Findings

Resonance peak around 2150 MeV consistent with X(2175)

Invariant mass of $K ar{K}$ near 970 MeV matching $f_0(980)$

No resonance observed in I=1 channel

Abstract

We perform a Faddeev calculation for the three mesons system, $\phi K \bar{K}$, taking the interaction between two pseudoscalar mesons and between a vector and a pseudoscalar meson from the chiral unitary approach. We obtain a neat resonance peak around a total mass of 2150 MeV and an invariant mass for the $K \bar{K}$ system around 970 MeV, very close to the $f_0(980)$ mass. The state appears in I=0 and qualifies as a $\phi f_0(980)$ resonance. We enlarge the space of states including $\phi \pi \pi$, since $\pi \pi$ and $K \bar{K}$ build up the $f_0$ (980), and find moderate changes that serve to quantify theoretical uncertainties. No state is seen in I=1. This finding provides a natural explanation for the recent state found at BABAR and BES, the X(2175), which decays into $\phi f_0(980)$.