Odd and Even Partial Waves of $\hat{I}\cdot \ddot{I}{€}^{-}$ and $\hat{I}{\cdot }^{\prime }\ddot{I}{€}^{-}$ in $\ddot{I}{€}^{-}p\to \hat{I}{\cdot }^{(\prime )}\ddot{I}{€}^{-}p$ at $191\text{GeV}/c$

Abstract

Exclusive production of $\hat{I}\cdot \ddot{I}{€}^{-}$ and $\hat{I}{\cdot }^{\prime }\ddot{I}{€}^{-}$ has been studied with a $191\text{GeV}/c$ $\ddot{I}{€}^{-}$ 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 $3\text{GeV}/c^2$. 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 $a_2(1320)$ and $a_4(2040)$ are in line with this similarity. In contrast, a strong enhancement of $\hat{I}{\cdot }^{\prime }\ddot{I}{€}^{-}$ over $\hat{I}\cdot \ddot{I}{€}^{-}$ is found for the $L=1,3,5$ waves, which carry non-$q\bar{q}$ quantum numbers. The $L=1$ intensity peaks at $1.7\text{GeV}/c^2$ in $\hat{I}{\cdot }^{\prime }\ddot{I}{€}^{-}$ and at $1.4\text{GeV}/c^2$ in $\hat{I}\cdot \ddot{I}{€}^{-}$, the corresponding phase motions with respect to $L=2$ are different.

16 pages, 5 figures and 1 table