1. In-medium modifications of the $\pi\pi$ interaction in photon-induced reactions
- Author
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Messchendorp, J. G., Janssen, S., Kotulla, M., Ahrens, J., Annand, J. R. H., Beck, R., Bloch, F., Caselotti, G., Fog, L., Hornidge, D., Krusche, B., Langgärtner, W., McGeorge, J. C., MacGregor, I. J. D., Mengel, K., Metag, V., Novotny, R., Owens, R. O., Pfeiffer, M., Sack, S., Sanderson, R., and Schadmand, S.
- Subjects
Nuclear Experiment - Abstract
Differential cross sections of the reactions $(\gamma,\pi^\circ\pi^\circ)$ and $(\gamma,\pi^\circ\pi^++\pi^\circ\pi^-)$ have been measured for several nuclei ($^1$H,$^{12}$C, and $^{\rm nat}$Pb) at an incident-photon energy of $E_{\gamma}$=400-460 MeV at the tagged-photon facility at MAMI-B using the TAPS spectrometer. A significant nuclear-mass dependence of the $\pi\pi$ invariant-mass distribution is found in the $\pi^\circ\pi^\circ$ channel. This dependence is not observed in the $\pi^\circ\pi^{+/-}$ channel and is consistent with an in-medium modification of the $\pi\pi$ interaction in the $I$=$J$=0 channel. The data are compared to $\pi$-induced measurements and to calculations within a chiral-unitary approach.
- Published
- 2002
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