Exclusive measurement of the eta -> pi(+) pi(-) gamma decay
2012 (English)In: Physics Letters B, ISSN 0370-2693, Vol. 707, no 2, 243-249 p.Article in journal (Refereed) Published
An exclusive measurement of the decay eta -> pi(+) pi(-) gamma has been performed at the WASA facility at COSY. The eta mesons were produced in the fusion reaction pd -> He-3 X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13 960 +/- 140 events after background subtraction. The measured pion angular distribution is consistent with a relative p-wave of the two-pion system, whereas the measured photon energy spectrum was found at variance with the simplest gauge invariant matrix element of eta -> pi(+) pi(-) gamma. A parameterization of the data can be achieved by the additional inclusion of the empirical pion vector form factor multiplied by a first-order polynomial in the squared invariant mass of the pi(+) pi(-) system.
Place, publisher, year, edition, pages
2012. Vol. 707, no 2, 243-249 p.
eta meson, Box anomaly, Exclusive measurement
IdentifiersURN: urn:nbn:se:uu:diva-169964DOI: 10.1016/j.physletb.2011.12.027ISI: 000300134400002OAI: oai:DiVA.org:uu-169964DiVA: diva2:508412