Abstract.
Preliminary differential cross-sections of the reactions \(A(\gamma,\pi^{0}\pi^{0})\) and \(A(\gamma,\pi^{0}\pi^ + + \pi^{0}\pi^-)\) with A = 1 H, 12 C, and nat Pb are presented. A significant nuclear-mass dependence of the \(\pi\pi\) invariant-mass distribution is found in the \(\pi^{0}\pi^{0}\) channel. The dependence is not observed in the \(\pi^{0}\pi^{\pm}\) channel. The in-medium observation in the \(\pi^{0}\pi^{0}\) channel is consistent with an in-medium modification of the \(\pi\pi\) interaction in the I = J = 0 channel, changing width and pole position of a \(\pi\pi\) resonant state.
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Received: 30 September 2002, Published online: 22 October 2003
PACS:
13.60.Le Meson production - 21.65. + f Nuclear matter
J.G. Messchendorp: For the TAPS and A2 Collaborations
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Messchendorp, J.G. \(\pi\pi\) correlations in \(\gamma + A\) reactions. Eur. Phys. J. A 18, 417–419 (2003). https://doi.org/10.1140/epja/i2002-10249-7
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DOI: https://doi.org/10.1140/epja/i2002-10249-7