Sensitivity study of X(3872) total width at the Belle II experiment

The X(3872) is a candidate of the exotic hadron. Studying the X(3872) partial widths is a good probe for investigating the internal structure of this hadronic state. In order to derive partial widths, the measurements of the total width is important. The Belle II experiment is the best environment to measure the total width of the X(3872), because an amount of data is 50 times higher than that of the Belle experiment. Thanks to the huge statistics, it is possible to use the X(3872) → D⁰D-bar⁰π⁰ decay, which has better mass resolution than a conventional X(3872) → J/ψπ⁺π^- decay because of small Q-value. In this work, the sensitivity of the X(3872) total width is estimated with the simulation at Belle II. It is found that the available statistics is around half of that with the X(3872) → J/ψπ⁺π^- decay, but it has around 3 times better mass resolution. Estimated 90% confidence level upper limit on the total width is around 180 keV with the full data sets, 50 ab^-1, which is 6.7 times better than the current most stringent upper limit of 1.2 MeV. This work also shows that there is a possibility to measure the total width with 3σ or 5σ significances at Belle II. (author)