Odd and even partial waves of $ηπ^−$ and $η′π^−$ in $π^−p → η^{(′)}π^−p$ at 191 GeV/c

COMPASS collaboration (207 authors)Bordalo, P.Franco, C.Nunes, Ana SofiaQuaresma, M.Quintans, C.Ramos, S.Silva, L.Stolarski, M.2019-02-042019-02-042014-11-30http://dx.doi.org/10.1016/j.physletb.2014.11.058http://hdl.handle.net/10400.26/26667Exclusive production of ηπ− and η′π− has been studied with a 191 GeV/c π− beam impinging on a hydrogen target at COMPASS (CERN). Partial-wave analyses reveal different odd/even angular momentum ( L ) characteristics in the inspected invariant mass range up to 3 GeV/c2 . A striking similarity between the two systems is observed for the L=2,4,6 intensities (scaled by kinematical factors) and the relative phases. The known resonances a2(1320) and a4(2040) are in line with this similarity. In contrast, a strong enhancement of η′π− over ηπ− is found for the L=1,3,5 waves, which carry non- qq¯ quantum numbers. The L=1 intensity peaks at 1.7 GeV/c2 in η′π− and at 1.4 GeV/c2 in ηπ− , the corresponding phase motions with respect to L=2 are different.engOdd and even partial waves of $ηπ^−$ and $η′π^−$ in $π^−p → η^{(′)}π^−p$ at 191 GeV/cjournal article2019-02-04