Messchendorp JG, Janssen S, Kotulla M, Ahrens J, Annand JRH, Beck R, Bloch F, Caselotti G, Fog L, Hornidge D, Krusche B, Langgärtner W, McGeorge JC, MacGregor IJD, Mengel K, Metag V, Novotny R, Owens RO, Pfeiffer M, Sack S, Sanderson R, Schadmand S. In-medium modifications of the pipi interaction in photon-induced reactions.
Phys Rev Lett 2002;
89:222302. [PMID:
12485064 DOI:
10.1103/physrevlett.89.222302]
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Abstract
Differential cross sections of the reactions (gamma,pi(0)pi(0)) and (gamma,pi(0)pi(+/-)) have been measured for several nuclei (1H,12C, and (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 pipi invariant-mass distribution is found in the pi(0)pi(0) channel. This dependence is not observed in the pi(0)pi(+/-) channel and is consistent with an in-medium modification of the pipi interaction in the I=J=0 channel. The data are compared to pi-induced measurements and to calculations within a chiral-unitary approach.
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