Observation of the B0s → χc1(3872)π+π− decay - Aaij, Roel; Bachmann, Sebastian; Borsato, Martino; Caspary, Rowina; Frau, Giulia; Günther, Paul André; Han, Xiaoxue; Hansmann-Menzemer, Stephanie; Hu, Jiangqiao; Leverington, Blake; Marks, Jörg; Morgenthaler, Maurice Pierre; et al. (Journal of high energy physics, 2023)