A new measurement of the K-+/- -> pi(+/-)gamma gamma decay at the NA48/2 experiment

Batley, Jr; 21 Kalmus G, 1; 1 Lazzeroni C,; 1 Munday DJ,; 1 Slater MW,; 1 Wotton SA,; 1 Arcidiacono R,; 2 Bocquet G,; 2 Cabibbo N,; 2 Ceccucci A,; 2 Cundy D,; 2 Falaleev V,; 2 Fidecaro M,; 2 Gatignon L,; 2 Gonidec A,; 2 Kubischta W,; 2 Norton A,; 2 Maier A,; 2 Patel M,; 2 Peters A,; 2 Balev S,; 3 Frabetti PL,; 3 Gersabeck E,; 3 Goudzovski E,; 3 Hristov P,; 3 Kekelidze V,; 3 Kozhuharov V,; 3 Litov L,; 3 Madigozhin D,; 3 Molokanova N,; 3 Polenkevich I,; 3 Potrebenikov Y,; 3 Stoynev S,; 3 Zinchenko A,; 3 Monnier E,; 4 Swallow E,; 4 Winston R,; 4 Rubin P,; 5 Walker A,; 5 Baldini Wander 6,; 7 Cotta Ramusino Angelo 6,; 7 Dalpiaz Pietro 6,; 7 Damiani Chiara 6,; 7 Fiorini Massimiliano 6,; 7 Gianoli Alberto 6,; 7 Martini Mara 6,; 7 Petrucci Ferruccio 6,; 7 Savrie' Mauro 6,; 7 Scarpa Marcella 6,; 7 Wahl Heinrich 6,; 7 Bizzeti Andrea,; Massimo, Lenti; Veltri, Michele; Mario, Calvetti; Enrico, Celeghini; Enrico, Iacopini; Ruggiero Giuseppe 8, 9 Behler M; 10 Eppard, K; 10 Kleinknecht, K; 10 Marouelli, P; 10 Masetti, L; 10 Moosbrugger, U; 10 Morales CM,; 10 Renk, B; 10 Wache, M; 10 Wanke, R; 10 Winhart, A; 10 Coward, D; 11 Dabrowski, A; 11 Martin TF,; 11 Shieh, M; 11 Szleper, M; 11 Velasco, M; 11 Wood MD,; 11 Cenci Patrizia 12 Pepe Monica 12 Petrucci Maria Carmela 12 Anzivino Giuseppina 12,; 13 Imbergamo Ermanno 12,; 13 Nappi Aniello 12,; 13 Piccini Mauro 12,; 13 Raggi Mauro 12,; 13 Valdata Nappi, M; 12,; 13 Cerri Claudio 14 Fantechi Riccardo 14 Collazuol Gianmaria 14,; 15 DiLella, L; 14,; 15 Lamanna Gianluca 14,; 15 Mannelli Italo 14,; 15 Michetti Andrea 14,; 15 Costantini Flavio 14,; 16 Doble, N; 14,; 16 Fiorini Luca 14,; 16 Giudici Sergio 14,; 16 Pierazzini Giuseppe 14,; 16 Sozzi Marco 14,; 16 Venditti Stefano 14,; 16 Bloch Devaux, B; 17 Cheshkov, C; 17 Cheze JB,; 17 De Beer, M; 17 Derre, J; 17 Marel, G; 17 Mazzucato, E; 17 Peyaud, B; 17 Vallage, B; 17 Holder, M; 18 Ziolkowski, M; 18 Biino Cristina 19 Cartiglia Nicolo' 19 Marchetto Flavio Pietro 19 Bifani Simone 19,; 20 Clemencic Marco 19,; 20 Goy Lopez Silvia 19,; 20 Dibon, H; 21 Jeitler, M; 21 Markytan, M; 21 Mikulec, I; 21 Neuhofer, G; 21 Widhalm, L.

doi:10.1016/j.physletb.2014.01.038

The NA48/2 experiment at CERN collected two data samples with minimum bias trigger conditions in 2003 and 2004. A measurement of the rate and dynamic properties of the rare decay K-+/- -> pi(+/-)gamma gamma from these data sets based on 149 decay candidates with an estimated background of 15.5 +/- 0.7 events is reported. The model-independent branching ratio in the kinematic range z = (m(gamma gamma)/m(K))(2) > 0.2 is measured to be B-MI(z > 0.2) = (0.877 +/- 0.089) x 10(-6), and the branching ratio in the full kinematic range assuming a particular Chiral Perturbation Theory description to be B(K-pi gamma gamma) = (0.910 +/- 0.075) x 10(-6). (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).