Measurement of the decay η ′ → π 0 π 0 η at MAMI
- Adlarson, P.
- Afzal, F.
- Cividini, F.
- Collicott, C.
- Costanza, S.
- Denig, A.
- Downie, E. J.
- Dieterle, M.
- Ferretti Bondy, M. I.
- Gardner, S.
- Garni, S.
- Glazier, D. I.
- Ahmed, Z.
- Glowa, D.
- Gradl, W.
- Gurevich, G.
- Hamilton, D. J.
- Hornidge, D.
- Huber, G. M.
- Käser, A.
- Kashevarov, V. L.
- Kay, S.
- Keshelashvili, I.
- Akondi, C. S.
- Kondratiev, R.
- Korolija, M.
- Krusche, B.
- Lazarev, A.
- Linturi, J.
- Livingston, K.
- MacGregor, I. J. D.
- Manley, D. M.
- Martel, P. P.
- McGeorge, J. C.
- Annand, J. R. M.
- Middleton, D. G.
- Miskimen, R.
- Mushkarenkov, A.
- Neganov, A.
- Neiser, A.
- Oberle, M.
- Ostrick, M.
- Ott, P.
- Otte, P. B.
- Oussena, B.
- Arends, H. J.
- Paudyal, D.
- Pedroni, P.
- Polonski, A.
- Prakhov, S.
- Rajabi, A.
- Ron, G.
- Rostomyan, T.
- Sarty, A.
- Sfienti, C.
- Sokhoyan, V.
- Beck, R.
- Spieker, K.
- Steffen, O.
- Strakovsky, I. I.
- Strub, T.
- Supek, I.
- Thiel, A.
- Thiel, M.
- Tiator, L.
- Thomas, A.
- Unverzagt, M.
- Borisov, N.
- Usov, Y. A.
- Wagner, S.
- Watts, D. P.
- Werthmüller, D.
- Wettig, J.
- Witthauer, L.
- Wolfes, M.
- Workman, R. L.
- Zana, L. A.
- Braghieri, A.
- Briscoe, W. J.
DOIAbstract
An experimental study of the η′→π0π0η→6γ decay has been conducted with the best up-to-date statistical accuracy, by measuring η′ mesons produced in the γp→η′p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The results obtained for the standard parametrization of the η′→π0π0η matrix element are consistent with the most recent results for η′→ππη decays, but have smaller uncertainties. The available statistics and experimental resolution allowed, for the first time, an observation of a structure below the π+π− mass threshold, the magnitude and sign of which, checked within the framework of the nonrelativistic effective-field theory, demonstrated good agreement with the cusp that was predicted based on the ππ scatteri...
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