Enhanced evidence of $X(7200)$ and improved measurements of $X(6900)$ parameters from a combined LHCb-ATLAS-CMS analysis

TL;DR

This paper combines data from LHCb, ATLAS, and CMS to enhance evidence for the $X(7200)$ state and improve measurements of the $X(6900)$ resonance, emphasizing interference effects in fully-charmed tetraquark spectroscopy.

Contribution

It presents the first combined analysis of multiple experiments to confirm the $X(7200)$ and refine $X(6900)$ parameters, highlighting interference effects.

Findings

$X(6900)$ observed with >12σ significance and precise parameters.

$X(7200)$ evidence ranges from 3.7σ to 6.6σ, best at 6.6σ with CMS data.

Interference effects are crucial in fully-charmed tetraquark analysis.

Abstract

We report enhanced evidence for the $X(7200)$ state and significantly improved measurements of the $X(6900)$ resonance parameters through a combined analysis of the di-$J/\psi$ mass spectrum using published data from LHCb, ATLAS, and CMS. By performing simultaneous fits to all three experiments, we observe the $X(6900)$ with overwhelming significance ($>12\sigma$) and determine its mass and width with improved precision. For the $X(7200)$, we find consistent signals across multiple interference models, with significances ranging from $3.7\sigma$ to $6.6\sigma$; the best-fit model (adopting the CMS three-resonance scheme) yields $6.6\sigma$ significance, providing substantially strengthened evidence for this state. Our results underscore the essential role of interference effects in fully-charmed tetraquark spectroscopy and offer new constraints on their production mechanisms at the LHC.