Observation and investigation of the T c c ¯ 1 ( 4430 ) + structure in B + → ψ ( 2 S ) K S 0 π + decays

The first four-dimensional amplitude analysis of the B + → ψ ( 2 S ) K S 0 π + decay is performed with proton-proton collision data collected by the LHCb experiment at s = 13 TeV , corresponding to an integrated luminosity of 5.4 f b − 1 . The data cannot be fully explained by B + → ψ ( 2 S ) K * + contributions alone. A significantly better description of the data is obtained by adding a T c c ¯ + contribution decaying to ψ ( 2 S ) π + . The properties of the T c c ¯ + structure are consistent with the exotic state T c c ¯ 1 ( 4430 ) + reported in the isospin-related B ¯ 0 → ψ ( 2 S ) K − π + decay. Effects of a possible T c c ¯ 1 ( 4430 ) + → D ¯ 1 * ( 2600 ) 0 D + decay mode on the T c c ¯ 1 ( 4430 ) + → ψ ( 2 S ) π +