Λs(1405) and negative parity baryon states

After a brief historical background on the Λs(1405), we revisit the 25 year old controversy on whether Λs(1405) is a qqq (L=1) three quark state or a K̄N quasi virtual bound state. This work is stimulated by the recent suggestion of Isgur that s be treated as a heavy quark in heavy quark effective theory HQET. We re-examine the empirical evidence for minimal mixing amongst singlets and octets in negative parity baryon states, with a possible dynamical origin in the opening of inelastic threshold channels. Finally, we suggest that Λs(1405) belongs to a class of hadrons which are described simultaneously as qqq or qq states and as hadronic bound states.