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First measurement of helicity-dependent cross sections in pi(0)n photoproduction from quasi-free nucleons

Kaser, A. and Dieterle, M. and Witthauer, L. and Abt, S. and Achenbach, P. and Adlarson, P. and Afzal, F. and Ahmed, Z. and Ahrens, J. and Annand, J. R. M. and Arends, H. J. and Bashkanov, M. and Beck, R. and Biroth, M. and Borisov, N. S. and Braghieri, A. and Briscoe, W. J. and Cividini, F. and Collicott, C. and Costanza, S. and Denig, A. and Downie, E. J. and Drexler, P. and Fix, A. and Garni, S. and Glazier, D. I. and Gorodnov, I. and Gradl, W. and Gunther, M. and Gurevich, G. M. and Heijkenskjoeld, L. and Hornidge, D. and Huber, G. M. and Kashevarov, V. L. and Kay, S. and Keshelashvili, I. and Kondratiev, R. and Korolija, M. and Krusche, B. and Lazarev, A. B. and Lisin, V. and Livingston, K. and Lutterer, S. and MacGregor, I. J. D. and Manley, D. M. and Martel, P. P. and Metag, V. and Meyer, W. and Miskimen, R. and Mornacchi, E. and Mushkarenkov, A. and Neganov, A. B. and Neiser, A. and Oberle, M. and Ostrick, M. and Otte, P. B. and Paudyal, D. and Pedroni, P. and Polonski, A. and Prakhov, S. N. and Reicherz, G. and Ron, G. and Rostomyan, T. and Sarty, A. and Sfienti, C. and Sokhoyan, V. and Spieker, K. and Steffen, O. and Strakovsky, I. I. and Strub, Th. and Supek, I. and Thiel, A. and Thiel, M. and Thomas, A. and Unverzagt, M. and Usov, Yu. A. and Wagner, S. and Walford, N. K. and Watts, D. P. and Werthmuller, D. and Wettig, J. and Wolfes, M. and Zana, L.. (2018) First measurement of helicity-dependent cross sections in pi(0)n photoproduction from quasi-free nucleons. PHYSICS LETTERS B, 786. pp. 305-312.

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Official URL: https://edoc.unibas.ch/69455/

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Abstract

The helicity-dependent cross sections for the photoproduction of pairs have been measured for the first time. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball – TAPS calorimeter. The experiment used a polarized deuterated butanol target and a circularly polarized photon beam. This arrangement allowed the (photon and target spin antiparallel) and (parallel spins) components to be measured for quasi-free production of pairs off protons and neutrons. The main finding is that the two helicity components contribute identically, within uncertainties, for both participant protons and neutrons. The absolute couplings for protons and neutrons are also identical. This means that nucleon resonances contributing to this reaction in the investigated energy range have almost equal electromagnetic helicity couplings, and . Identical couplings for protons and neutrons are typical for Δ resonances and identical and components are only possible for states, which constrains possible contributions of nucleon resonances.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Hadronenphysik (Krusche)
UniBasel Contributors:Krusche, Bernd
Item Type:Article, refereed
Article Subtype:Research Article
ISSN:0370-2693
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:16 Oct 2019 14:16
Deposited On:08 Oct 2019 09:26

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