Two-photon decay of fully-charmed tetraquarks from light-by-light scattering at the LHC

TL;DR

This paper proposes that the newly observed resonant structures around 7 GeV at the LHC, possibly fully-charmed tetraquarks, can explain the excess in light-by-light scattering, with implications for their decay properties and future detection.

Contribution

It introduces the hypothesis that fully-charmed tetraquarks contribute to light-by-light scattering at the LHC, providing a potential explanation for the observed excess and predicting their gamma-gamma branching ratios.

Findings

The ATLAS data can be explained by a tetraquark state with a gamma-gamma branching ratio of about 10^{-4}.

This branching ratio is larger than vector-meson dominance predictions but aligns with tetraquark models.

Further LHC data are needed to confirm the tetraquark nature of these states.

Abstract

The LHC newly-discovered resonant structures around 7 GeV, such as the $X(6900)$, could be responsible for the observed excess in light-by-light scattering between 5 and 10 GeV. We show that the ATLAS data for light-by-light scattering may indeed be explained by such a state with the $\gamma \gamma$ branching ratio of order of $10^{-4}$. This is much larger than the value inferred by the vector-meson dominance, but agrees quite well with the tetraquark expectation for the nature of this state. Further light-by-light scattering data in this region, obtained during the ongoing Run-3 and future Run-4 of the LHC, are required to pin down these states in $\gamma\gamma$ channel.