Partial-wave analysis in the Q region of (ππ)− systems produced in K−p reactions at 4.2 GeV/c

Abstract A partial-wave analysis and an isospin analysis are presented of the ( K ππ) − systems produced in the reactions K − p → K − π − π + and K − p → K 0 π − π − p u sing the high-statistics bubble-chamber data at 4.2 GeV/ c . The energy dependence of J P = 1 + waves is investigated in a comparison with results at higher energy. The dominant 1 + 0+ ( K ∗ π) with its maximum in the Q 2 (1.4 GeV) region is an almost pure I = 1 2 state. The energy dependence of 1 + 0+ (K ∗ π) at low masses is consistent with pomeron exchange while at higher masses (including the Q 2 region) other natural exchanges are involved. The 1 ∗ 1+ (K ϱ ) has its maximum at about 1.3 GeV. The relative phase between these two 1 + states is consistent with Q 1 −Q 2 contribution to the 1 + state. Properties of the Q resonances are obtained in a fit of a two-resonance model to the 1 + date. There is no clear evidence for the 0 − resonance seen at SLAC.