In-medium modifications of the ππ interaction in photon-induced reactions

Sack, S

doi:10.1103/physrevlett.89.222302

In-medium modifications of the ππ interaction in photon-induced reactions

Date Issued

2002-01-01

Author(s)

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

Schadmand, S

DOI

10.1103/physrevlett.89.222302

Abstract

Differential cross sections of the reactions (gamma,pi(0)pi(0)) and (gamma,pi(0)pi(+/-)) have been measured for several nuclei (H-1,C-12, and Pb-nat) 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.