  We have found theoretically that the elementary process, p + p to K+ +
Lambda(1405) + p, which occurs in a short impact parameter (around 0.2 fm) and
with a large momentum transfer (Q ~ 1.6 GeV/c), leads to unusually large
self-trapping of Lambda(1405) by the projectile proton, when a Lambda* -p
system exists as a dense bound state (size ~ 1.0 fm) propagating to K^-pp. The
seed, called "Lambda*-p doorway", is expected to play an important role in the
(p, K*) type reactions and heavy-ion collisions to produce various Kbar nuclear
clusters.
