| 摘要: |
The X(3872) is the first and the most interesting one amongst the abundant XYZ states. Its mass coincides exactly with the D-0(D) over bar*(0) threshold with an uncertainty of 180 keV. Precise knowledge of its mass is crucial to understand the X(3872). However, whether it is above or below the D-0(D) over bar*(0) threshold is still unknown. We propose a completely new method to measure the X(3872) mass precisely by measuring the X(3872)gamma line shape between 4010 and 4020 MeV, which is strongly sensitive to the X(3872) mass relative to the D-0(D) over bar*(0) threshold due to a triangle singularity. This method can be applied to experiments which produce copious D*(0)(D) over bar*(0) pairs, such as electron-positron, proton-antiproton, and other experiments, and may lead to much more precise knowledge of the X(3872) mass. |
