Some (further) Comments on the Theta(1540) Pentaquark

Abstract

Additional broader I=0 states in the KN channel near $Θ^+$(1540) are expected in many models, making the absence of any signature in the K$^+$-deuteron scattering data even more puzzling. In an ideal "three-body" picture the $Θ$ is viewed as two compact ud(1)ud(2) $\bar{3}$ color diquarks and an $\bar{s}$ quark. A "QCD-type" inequality involving $m(Θ^+), m(Λ)$, the mass of the $Λ(1/2^-) $ L=1 excitation and that of a new I=0 tetraquark vector meson then follows. The inequality suggests a very light new vector meson, and is violated. We note that "associated production" of the pentaquark with another quadriquark or anti-pentaquark may be favored. This along with some estimates of the actual production cross sections suggest that the $Θ$ can be found in BaBar or Belle e$^+$-e$^-$ colliders.