2020 Impact factor 3.043
Hadrons and Nuclei
Eur. Phys. J. A 4, 209-216

Short note

Evidence for narrow $\Delta^0(1232)$ states in the ${}^{12}C(e,e'p\pi^-){}^{11}C$ Reaction

P. Bartsch1 - D. Baumann1 - J. Bermuth2 - K. Bohinc3 - R. Böhm1 - D. Bosnar4 - N. Clawiter1 - S. Derber1 - M. Ding1 - M.O. Distler1 - A. Ebbes1 - I. Ewald1 - J. M. Friedrich1 - J. Friedrich1 - P. Jennewein1 - M. Kahrau1 - M. Kohl5 - A. Kozlov1 - K.W. Krygier1 - M. Kuss5 - A. Liesenfeld1 - H. Merkel1 - P. Merle1 - U. Müller1 - R. Neuhausen1 - T. Pospischil1 - M. Potokar3 - D. Rohe2 - G. Rosner1 - H. Schmieden1 - S. Sirca3 - A. Wagner1 - T. Walcher1 - M. Weis1 - S. Wolf1

1 Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
2 Institut für Physik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
3 Institut "Jozef Stefan'', University of Ljubljana, SI-1001 Ljubljana, Slovenia
4 Department of Physics, University of Zagreb, HR-10000 Zagreb, Croatia
5 Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany

Received: 23 December 1998 Communicated by B. Povh

The reaction ${}^{12}C(e,e'\Delta^0){}^{11}C\rightarrow
 {}^{12}C(e,e'p\pi^-){}^{11}C$ was investigated at the Mainz Microtron MAMI in a triple coincidence measurement using the three spectrometer setup of the A1 Collaboration. The good missing mass resolution of $\sigma_{\mathrm m} = 0.27\,MeV/c^2$ allowed to select the events belonging to the ground state of 11C. Cutting on these events the excitation energy spectra of ${}^{12}C_{\Delta^0}$ show evidence for two peaks of about $4\,MeV$ width (FWHM) at $282\,MeV$ and $296\,MeV$ with a significance of about 4.5 standard deviations. The peaks are interpreted in a simple weak coupling model as bound $\Delta^0$ states in ${}^{12}C_{\Delta^0}$.

24.30.Gd Nuclear physics: Resonance reactions - 25.30.Rw Electroproduction reactions - 14.20.Gk Baryon resonances with S=0 - 21.80.+a Hypernuclei

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