First measurement of direct photoproduction of the $a_2(1320)^0$ meson on the proton

A. Celentano , M. Battaglieri , R. de Vita , L. Marsicano , V. Mathieu , A. Pilloni , A. Szczepaniak , K.P. Adhikari , S. Adhikari , M.J. Amaryan , G. Angelini , H. Atac , L. Barion , I. Bedlinskiy , Fatiha Benmokhtar , A. Bianconi , A.S. Biselli , F. Bossù (1) , S. Boiarinov , W.J. Briscoe , W.K. Brooks , D. Bulumulla , V.D. Burkert , D.S. Carman , J.C. Carvajal , P. Chatagnon (2) , T. Chetry , G. Ciullo , L. Clark , P.L. Cole , M. Contalbrigo , O. Cortes , V. Crede , R. Cruz-Torres , A. d'Angelo , N. Dashyan , M. Defurne (1) , A. Deur , S. Diehl , C. Djalali , M. Dugger , R. Dupre (2) , H. Egiyan , M. Ehrhart , A. El Alaoui , L. El Fassi , L. Elouadrhiri , P. Eugenio , G. Fedotov , R. Fersch , A. Filippi , G. Gavalian , N. Gevorgyan , F.X. Girod (1) , D.I. Glazier , W. Gohn , E. Golovatch , R.W. Gothe , K.A. Griffioen , M. Guidal (2) , K. Hafidi , H. Hakobyan , N. Harrison , M. Hattawy , F. Hauenstein , T.B. Hayward , D. Heddle , K. Hicks , A. Hobart (2) , M. Holtrop , Y. Ilieva , D.G. Ireland , B.S. Ishkhanov , E.L. Isupov , D. Jenkins , H.S. Jo , K. Joo , S. Joosten , D. Keller , M. Khachatryan , A. Khanal , M. Khandaker , A. Kim , C.W. Kim , W. Kim , F.J. Klein , V. Kubarovsky , L. Lanza , M. Leali , P. Lenisa , K. Livingston , V. Lucherini , I.J.D. Macgregor , D. Marchand (2) , N. Markov , V. Mascagna , M.E. Mccracken , B. Mckinnon , Z.E. Meziani , M. Mirazita , V. Mokeev , A. Movsisyan , E. Munevar , C. Munoz Camacho (2) , P. Nadel-Turonski , K. Neupane , S. Niccolai (2) , G. Niculescu , M. Osipenko , A.I. Ostrovidov , M. Paolone , L.L. Pappalardo , R. Paremuzyan , E. Pasyuk , W. Phelps , O. Pogorelko , J.W. Price , Y. Prok , M. Ripani , J. Ritman , A. Rizzo , G. Rosner , J. Rowley , F. Sabatié (1) , C. Salgado , A. Schmidt , R.A. Schumacher , U. Shrestha , D. Sokan , O. Soto , N. Sparveris , S. Stepanyan , I.I. Strakovsky , S. Strauch , J.A. Tan , N. Tyler , M. Ungaro , L. Venturelli , H. Voskanyan , E. Voutier (2) , D. Watts , X. Wei , M.H. Wood , N. Zachariou , J. Zhang , Z.W. Zhao

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 IJCLab - Laboratoire de Physique des 2 Infinis Irène Joliot-Curie

We present the first measurement of the reaction γp→a2(1320)0p in the photon energy range 3.5–5.5GeV and four-momentum transfer squared 0.2<−t<2.0GeV2. Data were collected with the CEBAF Large Acceptance Spectrometer detector at the Thomas Jefferson National Accelerator Facility. The a2 resonance was detected by measuring the reaction γp→π0ηp and reconstructing the π0η invariant mass. The most prominent feature of the differential cross section is a dip at −t≈0.55GeV2. This can be described in the framework of Regge phenomenology, where the exchange degeneracy hypothesis predicts a zero in the reaction amplitude for this value of the four-momentum transfer.

Mots clés: Hadronic Physics and QCD; photon: energy; beam: energy; differential cross section: measured; meson: photoproduction; Regge; CLAS; photon p: inelastic scattering; photon p: exclusive reaction; experimental results; mass spectrum: (pi0 eta); angular distribution; partial wave analysis

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique des Hautes Energies - Expérience [hep-ex]; Physique Nucléaire Théorique [nucl-th]

A. Celentano, M. Battaglieri, R. de Vita, L. Marsicano, V. Mathieu, et al.. First measurement of direct photoproduction of the $a_2(1320)^0$ meson on the proton. Phys.Rev.C, 2020, 102 (3), pp.032201. ⟨10.1103/PhysRevC.102.032201⟩. ⟨hal-02557695⟩