Resonant behavior of the $pp\to \{pp{\}}_s{\pi }^0$ reaction at the energy $\sqrt{s}$ = 2.65 GeV

Abstract

We report on measurements of the differential cross section $d\sigma /d\Omega$ in the energy region of $\sqrt{s}$ = 2.5-2.9 GeV of the reaction $pp\to \{pp{\}}_s{\pi }^0$ where $\{pp{\}}_s$ is a ${}^1{S}_0$ proton pair. The experiment has been performed with the ANKE spectrometer at COSY-Jülich. The data reveal a peak in the energy dependence of the forward $\{pp{\}}_s$ differential cross section at the energy $\sqrt{s}$ = 2.65 GeV with the width $\Gamma$ = 0.26 GeV, and also the cross section slope changes its sign in the region of the observed peak. This is an indication for the excitation of a new $D(2650)$ resonant state, that may be a dibaryon resonance system consisting of two excited baryons $\Delta (1232)$ and $N^{\ast }(1440)$.

6 pages, 7 figures

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