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EnglishThe K-L --> pi(+)pi(-)e(+)e(-) and K-S --> pi(+) pi(-) e(+) e(-) decay modes have been studied in detail using the NA48 detector at the CERN SPS. Based on the data collected during the 1998 and 1999 run periods, a sample of 1162 K-L --> pi(+) pi(-) e(+)e(-) candidates has been observed with an expected background level of 36.9 events, yielding the branching ratio measurement BR(K-L --> pi(+) pi(-) e(+) e(-)) = (3.08 +/- 0.20) x 10(-7). The distribution of events in the sinphicosphi variable, where phi is the angle between the pi(+)pi(-) and the e(+)e(-) decay planes in the kaon centre of mass, is found to exhibit a large CP-violating asymmetry with the value A(phi) = (14.2 +/- 3.6)%. For the K-s --> pi(+) pi(-) e(+) e(-) decay channel, 621 candidates have been identified in the 1999 data sample with an estimated background contribution of 0.7 event. The corresponding branching ratio has been determined to be BR(K-s --> pi(+)pi(-)e(+)e(-)) = (4.71 +/- 0.32) x 10(-5). The combined value of this measurement with the published 1998 result is BR(K-s --> pi(+) pi(-) e(+)e(-)) = (4.69 +/- 0.30) X 10(-5). No asymmetry is observed in this decay mode. Our results are in good agreement with theoretical predictions based on a phenomenological description of radiative kaon decays. The form factor parameters a(1)/a(2) and (g) over tilde (M1) in the K-L --> pi(+)pi(-)e(+)e(-) direct emission process as well as the value of the K-0 charge radius have been extracted from the data.
| Autori interni: | |
| Autori: | Lai A; Marras D; Bevan A; Dosanjh RS; Gershon TJ; Hay B; Kalmus GE; Lazzeroni C; Munday DJ; Needham MD; Olaiya E; Parker MA; White TO; Wotton SA; Barr G; Bocquet G; Ceccucci A; Cundy D; Doble N; Falaleev V; Gatignon L; Gonidec A; Gorini B; Govi G; Grafstrom P; Kubischta W; Lenti M; Luitz S; Mikulec I; Norton A; Palestini S; Panzer-Steindel B; Taureg H; Velasco M; Wahl H; Cheshkov C; Gaponenko A; Hristov P; Kekelidze V; Madigojine D; Tatishvili G; Potrebenikov Y; Zinchenko A; Knowles I; Martin V; Sacco R; Walker A; Contalbrigo M; Dalpiaz P; Duclos J; Frabetti PL; Gianoli A; Martini M; Masetti L; Petrucci F; Savrie M; Bizzeti A; Calvetti M; Collazuol G; Graziani G; Iacopini E; Veltri M; Becker HG; Eppard M; Fox H; Holtz K; Kalter A; Kleinknecht K; Koch U; Kopke L; da Silva PL; Marouelli P; Pellmann I; Peters A; Schmidt SA; Schonharting V; Schue Y; Wanke R; Winhart A; Wittgen M; Chollet JC; Fayard L; Iconomidou-Fayard L; Ocariz J; Unal G; Wingerter-Seez I; Anzivino G; Cenci P; Imbergamo E; Lubrano P; Mestvirishvili A; Nappi A; Pepe M; Piccini M; Casali R; Cerri C; Cirilli M; Costantini F; Fantechi R; Giudici S; Mannelli I; Pierazzini G; Sozzi M; Cheze JB; Cogan J; De Beer M; Debu P; Formica A; de Cassagnac RG; Mazzucato E; Peyaud B; Turlay R; Vallage B; Holder M; Maier A; Ziolkowski M; Arcidiacono R; Biino C; Cartiglia N; Clemencic M; Marchetto F; Menichetti E; Nassalski J; Rondio E; Szleper M; Wislicki W; Wronka S; Fischer G; Jeitler M; Markytan M; Neuhofer G; Pernicka M; Taurok A; Widhalm L |
| Titolo: | Investigation of K-L,K-s -> pi(+)pi(-)e(+)e(-) decays |
| Anno del prodotto: | 2003 |
| Digital Object Identifier (DOI): | 10.1140/epjc/s2003-01252-y |
| Appare nelle tipologie: | 1.1 Articolo in rivista |
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