Measurement of the decay η0 → π0π0η at MAMI

Adlarson, P.; Afzal, F.; Ahmed, Z.; Akondi, C. S.; Annand, J. R. M.; Arends, H. J.; Beck, R.; Borisov, N.; Braghieri, A.; Briscoe, W. J.; Cividini, F.; Collicott, C.; Costanza, S.; Denig, A.; Downie, E. J.; Dieterle, M.; Ferretti Bondy, M. I.; Gardner, S.; Garni, S.; Glazier, D. I.; Glowa, D.; Gradl, W.; Gurevich, G.
.; Hamilton, D. J.; Hornidge, D.; Huber, G. M.; Käser, A.; Kashevarov, V. L.; Kay, S; Keshelashvili, I.; Kondratiev, R.; Korolija, M.
.; Krusche, B.; Lazarev, A; Linturi, James M.; Livingston, K.; Macgregor, I. J.D.; Manley, D. M.; Martel, P. P.; McGeorge, J. C.; Middleton, D. G.; Miskimen, R.; Mushkarenkov, A.; Neganov, A.; Neiser, A.; Oberle, M.; Ostrick, M.; Ott, P.; Otte, P. B.; Oussena, B.; Paudyal, D.; Pedroni, P.; Polonski, A.; Prakhov, S.; Rajabi, A.; Ron, G.; Rostomyan, T.; Sarty, A.; Sfienti, C.; Sokhoyan, V.; Spieker, K.; Steffen, O.; Strakovsky, I. I.; Strub, T.; Supek, I.; Thiel, A.; Thiel, M.; Tiator, L.; Thomas, A.; Unverzagt, M.; Usov, Y. A.; Wagner, S.; Watts, D. P.; Werthmüller, D.; Wettig, J.; Witthauer, L.; Wolfes, M.; Workman, R. L.; Zana, L. A.

Measurement of the decay η0 → π0π0η at MAMI

Adlarson, P.; Afzal, F.; Ahmed, Z.; Akondi, C. S.; Annand, J. R. M.; Arends, H. J.; Beck, R.; Borisov, N.; Braghieri, A.; Briscoe, W. J.; Cividini, F.; Collicott, C.; Costanza, S.; Denig, A.; Downie, E. J.; Dieterle, M.; Ferretti Bondy, M. I.; Gardner, S.; Garni, S.; Glazier, D. I.; Glowa, D.; Gradl, W.; Gurevich, G. .; Hamilton, D. J.; Hornidge, D.; Huber, G. M.; Käser, A.; Kashevarov, V. L.; Kay, S; Keshelashvili, I.; Kondratiev, R.; Korolija, M. .; Krusche, B.; Lazarev, A; Linturi, James M.; Livingston, K.; Macgregor, I. J.D.; Manley, D. M.; Martel, P. P.; McGeorge, J. C.; Middleton, D. G.; Miskimen, R.; Mushkarenkov, A.; Neganov, A.; Neiser, A.; Oberle, M.; Ostrick, M.; Ott, P.; Otte, P. B.; Oussena, B.; Paudyal, D.; Pedroni, P.; Polonski, A.; Prakhov, S.; Rajabi, A.; Ron, G.; Rostomyan, T.; Sarty, A.; Sfienti, C.; Sokhoyan, V.; Spieker, K.; ; Steffen, O.; Strakovsky, I. I.; Strub, T.; Supek, I.; Thiel, A.; Thiel, M.; Tiator, L.; Thomas, A.; Unverzagt, M.; Usov, Y. A.; Wagner, S.; Watts, D. P.; Werthmüller, D.; Wettig, J.; Witthauer, L.; Wolfes, M.; Workman, R. L.; Zana, L. A.

URI: https://journals.aps.org/prd/pdf/10.1103/PhysRevD.98.012001
http://repository.seku.ac.ke/handle/123456789/4290

Date: 2018

Abstract:

An experimental study of the η0 → π0π0η → 6γ decay has been conducted with the best up-to-date statistical accuracy, by measuring η0 mesons produced in the γp → η0 p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The results obtained for the standard parametrization of the η0 → π0π0η matrix element are consistent with the most recent results for η0 → ππη decays, but have smaller uncertainties. The available statistics and experimental resolution allowed, for the first time, an observation of a structure below the πþπ− 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 scattering length combination, a0 − a2, extracted from K → 3π decays