Pion inelastic scattering to the low-lying excited states of /sup 6/Li

The excitation function for ..pi../sup +/ inelastic scattering to the 0/sup +/, T = 1, 3.563-MeV level of /sup 6/Li has been measured at a constant momentum transfer qapprox. =109 MeV/c for incident pion energies from 100 to 260 MeV. Although the differential cross sections extracted for the natural-parity transitions to the 3/sup +/, T = 0, 2.185-MeV and 2/sup +/, T = 0, 4.25-MeV levels are well reproduced within the framework of the distorted-wave impulse approximation, distorted-wave impulse approximation calculations fail to reproduce the anomalous excitation function observed for the transition to the 3.563-MeV level. The shape of the 3.563-MeV excitation function is similar to that previously observed for ..pi../sup + -/ inelastic scattering to the 1/sup +/, T = 1, 15.11-MeV state of /sup 12/C (C.L. Morris et al., Phys. Lett. 108B, 172 (1982)). The same mechanism may be responsible for the observed excitation functions of both ..delta..S = ..delta..T = 1 transitions. A possible mechanism is the previously proposed direct excitation of ..delta..-particle--nucleon-hole (..delta..-h) components in the wave functions.