$\chi^{\vphantom\dagger}_{c0}(3915)$ As the Lightest $c\bar c s \bar s$ State

TL;DR

This paper proposes that the $ ext{chi}_{c0}(3915)$ is the lightest $car c s ar s$ tetraquark state, using the diquark model to explain its properties and related charmoniumlike states, including the $Y(4140)$.

Contribution

It introduces a novel interpretation of $ ext{chi}_{c0}(3915)$ as a $car c s ar s$ state and calculates the spectrum of such states using the diquark model.

Findings

$ ext{chi}_{c0}(3915)$ is likely a $car c s ar s$ state.

Many charmoniumlike states without open-charm decays are identified as $car c s ar s$.

$Y(4140)$ is a $J^{PC} = 1^{++}$ $car c s ar s$ state, explaining its non-observation in two-photon fusion.

Abstract

The state $\chi^{\vphantom\dagger}_{c0}(3915)$ has recently been demoted by the Particle Data Group from its previous status as the conventional $c\bar c$ $2 {}^3P_0$ state, largely due to the absence of expected $D\bar D$ decays. We propose that $\chi^{\vphantom\dagger}_{c0}(3915)$ is actually the lightest $c\bar c s \bar s$ state, and calculate the spectrum of such states using the diquark model, identifying many of the observed charmoniumlike states that lack open-charm decay modes as $c\bar c s \bar s$. Among other results, we argue that $Y(4140)$ is a $J^{PC} = 1^{++}$ $c\bar c s \bar s$ state that has been not been seen in two-photon fusion largely as a consequence of the Landau-Yang theorem.