First evidence of $X(3872)\to {\pi }^0{\chi }_{c0}(1P)$ and search for $X(3915)\to {\pi }^0{\chi }_{c1}(1P)$

Belle, Belle II Collaborations, : +412

We search for the pionic transitions $X(3872)\to {\pi }^0{\chi }_{cJ}(1P)$ $(J=0,1,2)$ and $X(3915)\to {\pi }^0{\chi }_{c1}$ in $B^{+}\to {\pi }^0{\chi }_{cJ}{K}^{+}$ decays using the Belle and Belle~II data samples c…