Observation of the selective coupling of K* states to the K−η channel

The K−η effective mass spectrum in the reaction K−p→K−π+π−π0p at 11 GeV/c has a prominent peak at ≈1.75 GeV/c2, which is shown to be due to the K3∗(1780) by a spherical harmonic moments analysis and amplitude decomposition; there is no significant signal for K2∗(1430). The measured branching fractions for the leading L=1 and L=2 K∗,s, [BF(K2∗ (1430)→Kη) BF ( K 3 ∗ (1780)→ Kη )=9.4±3.4%] confirm the SU(3) prediction that the Kη channel couples preferentially to odd spin K*,s.