Evidence for a newK ^* $\bar K$ state at a mass of 1,530 MeV withIJ ^PC=01⁺⁺ observed inK ⁻ p interactions at 4.2 GeV/c

Abstract

Evidence is presented for a newK ^* $\bar K$+c.c. resonance with a mass of (1,526±6) MeV, a width of (107±15) MeV and quantum numbersIJ ^PC=01⁺⁺. We call itD′ meson. Initially it is observed as aK ^* $\bar K$+c.c. enhancement in the reactionsK ⁻ p→(K ⁰_s K ^±π^∓)Λ at 4.2 GeV/c. The isospin assignmentI=0 comes from its further observation in the reactionsK ⁻ p→(K ⁰_s K ^±π^∓)Σ ⁰ andK ⁻ p→(K ⁰_s K ^±π^∓)Σ(1,385)⁰ but not inK ⁻ p→(K ⁺ K ⁻π⁻)Σ⁺ orK ⁻ p→(K ⁰_s K ^±π^∓)Σ(1,385)⁺. A maximum likelihood analysis of the (K $\bar K$π) decay Dalitz plots in the reactionsK ⁻ p→(K ⁰_s K ^±π^∓) determines theJ ^PC of theD′ meson to be 1⁺⁺. A satisfactorySU(3) fit is obtained to a 1⁺⁺ nonet composed of theI-1A ₁, theI=1/2Q _A with theD(1,285) and theD′(1,526) as theI=0 members having a mixing angle close to the magic one.