# Is the X(3872) a bound state ?

## TL;DR

This paper questions whether the X(3872) is a bound state by analyzing experimental data and theoretical cancellations, suggesting it may be a half-bound state rather than a true bound state.

## Contribution

It introduces a novel cancellation effect in the $1^{++}$ channel and compares experimental production data to challenge the bound state interpretation of X(3872).

## Key findings

- Cancellation in the $1^{++}$ channel affects invariant mass analysis.
- Experimental production rates are consistent with a half-bound state.
- The bound state nature of X(3872) is strongly questioned.

## Abstract

All existing experimental evidence of the bound state nature of the $X(3872)$ relies on considering its decay products with a finite experimental spectral mass resolution which is typically $\Delta m \ge 2 $MeV and much larger than its alleged binding energy, $B_X=0.00(18)$MeV. On the other hand, we have found recently that there is a neat cancellation in the $1^{++}$ channel for the invariant $D \bar D^*$ mass around the threshold between the continuum and bound state contribution. This is very much alike a similar cancellation in the proton-neutron continuum with the deuteron in the $1^{++}$ channel. Based on comparative fits of experimental cross section deuteron and $X(3872)$ prompt production in pp collisions data with a finite $p_T$ to a common Tsallis distribution we find a strong argument questioning the bound state nature of the state but also explaining the large observed production rate likely consistent with a half-bound state.