Evidence for a backward peak in the gamma d -> pi(0)d cross section near the eta threshold

CLAS Collaboration, Y. Ilieva, B. L. Berman, A. E. Kudryavtsev, I. I. Strakovsky, V. E. Tarasov, M. Amarian, P. Ambrozewicz, M. Anghinolfi, G. Asryan, H. Avakian, H. Bagdasaryan, N. Baillie, J. P. Ball, N. A. Baltzell, V. Batourine, M. Battaglieri, I. Bedlinskiy, M. Bellis, N. BenmounaA. S. Biselli, S. Bouchigny, S. Boiarinov, R. Bradford, D. Branford, W. J. Briscoe, W. K. Brooks, S. Bueltmann, V. D. Burkert, C. Butuceanu, J. R. Calarco, S. L. Careccia, D. S. Carman, S. Chen, P. L. Cole, P. Collins, P. Coltharp, D. Crabb, V. Crede, R. De Masi, E. De Sanctis, R. De Vita, P. V. Degtyarenko, A. Deur, R. Dickson, C. Djalali, G. E. Dodge, J. Donnelly, D. Doughty, M. Dugger, D. P. Watts

Research output: Contribution to journalArticlepeer-review


High-quality cross sections for the reaction gamma d -> pi(0)d have been measured using the CLAS at Jefferson Lab over a wide energy range near and above the eta-meson photoproduction threshold. At backward c.m. angles for the outgoing pions, we observe a resonance-like structure near E-gamma = 700 MeV. Our model analysis shows that it can be explained by eta excitation in the intermediate state. The effect is the result of the contribution of the N(1535) S-11-resonance to the amplitudes of the subprocesses occurring between the two nucleons and of a two-step process in which the excitation of an intermediate eta-meson dominates.

Original languageEnglish
Pages (from-to)261-267
Number of pages7
JournalEuropean Physical Journal A: Hadrons and Nuclei
Issue number3
Publication statusPublished - Mar 2010

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