Double π⁰ photoproduction off the proton at threshold

Kotulla, M. and Ahrens, J. and Annand, J. R. M. and Beck, R. and Hornidge, D. and Janssen, S. and Krusche, B. and McGeorge, J. C. and MacGregor, I. J. D. and Messchendorp, J. G. and Metag, V. and Novotny, R. and Pfeiffer, M. and Owens, R. O. and Rost, M. and Schadmand, S. and Watts, D. P.. (2004) Double π⁰ photoproduction off the proton at threshold. Physics letters. B, Vol. 578, H. 1-2. pp. 63-68.

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Official URL: http://edoc.unibas.ch/dok/A5261948

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The reaction gammap -< pi(0)pi(0)p has been measured using the TAPS BaF2 calorimeter at the tagged photon facility of the Mainz Microtron accelerator. Chiral perturbation theory (ChPT) predicts that close to threshold this channel is significantly enhanced compared to double pion final states with charged pions. In contrast to other reaction channels, the lower order tree terms are strongly suppressed in 2pi(0) photoproduction. The consequence is the dominance of pion loops in the 2pi(0) channel close to threshold-a result that opens new prospects for the test of ChPT and in particular its inherent loop terms. The present measurement is the first which is sensitive enough for a conclusive comparison with the ChPT calculation and is in agreement with its prediction. The data also show good agreement with a calculation in the unitary chiral approach.
Faculties and Departments:05 Faculty of Science > Departement Physik > Former Organization Units Physics > Hadronenphysik (Krusche)
UniBasel Contributors:Krusche, Bernd
Item Type:Article, refereed
Article Subtype:Research Article
Note:Variant title: Double pi(0) photoproduction off the proton at threshold -- Publication type according to Uni Basel Research Database: Journal article
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Last Modified:22 Mar 2012 14:26
Deposited On:22 Mar 2012 13:54

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