Measurement of the decay rate and the parameter alpha(K)* of the decay K-L ->mu mu gamma RID C-6551-2009 RID A-4071-2012

FANTI, VIVIANA;Lai A;Musa L;Nappi A;Setzu MG;Moore RW;Munday DJ;Parker MA;Takach SF;White TO;Barr G;Bocquet G;Bremer J;Ceccucci A;Cogan J;Cundy D;Doble N;Fischer G;Funk W;Gatignon L;Gianoli A;Gonidec A;Grafstrom P;Kubischta W;Marzulli V;Kesseler G;Matheys JP;Norton A;Palestini S;Panzer Steindel B;Taureg H;Velasco M;Vossnack O;Wahl H;Kekelidze V;Kojevnikov I;Potrebenikov I;Tatichvili G;Tkatchev A;Bertolotto L;Boyle O;Hay B;Mc Kay NE;Oakland G;Parsons H;Peach KJ;Talamonti C;Walker A;Dalpiaz P;Duclos J;Formica A;Frabetti PL;Martini M;Petrucci F;Porcu M;Rossi F;Savrie M;Simani C;Bizzeti A;Calvetti M;Lenti M;Michetti A;Becker HG;Beier T;Blumer H;Buchholz P;Coward D;Ebersberger C;Kalter A;Kleinknecht K;Koch U;Kopke L;Leber F;Luitz S;Renk B;Scheidt J;Schmidt J;Schonharting V;Wilhelm R;Zeitnitz O;Chollet JC;Crepe S;Fayard L;Ocariz J;Unal G;Anzivino G;Cenci P;Lubrano P;Pepe M;Calafiura P;Carosi R;Casali R;Cerri C;Costantini F;Fantechi R;Giudici S;Gorini B;Mannelli I;Pierazzini G;Sozzi M;Cheze JB;De Beer M;Debu P;Hristov P;Mazzucato E;Peyaud B;Schanne S;Steinkamp O;Turlay R;Vallage B;Augustin I;Bender M;Holder M;Schwarze I;Ziolkowski M;Arcidiacono R;Biino C;Govi G;Maas P;Marchetto F;Menichetti E;Dibon H;Jeitler M;Markytan M;Mikulec I;Neuhofer G;Pernicka M;Taurok A.

1997-01-01

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Abstract

The rate of the decay of the neutral K meson into K-L(0) --> mu mu gamma has been measured with the NA48 detector at the CERN SPS, Pi total of 59 events has been observed with an estimated background of 14 events. The overall Kaon flux was determined to he 1.2 x 10(9), This observation corresponds to a branching ratio of (3.4 +/- 0.6(stat) +/- 0.4(sys)) x 10(-7) Using this branching ratio the parameter alpha(K*) describing the relative strength of the two contributing amplitudes to this decay, through intermediate pseudoscalar or vectorlike mesons, was measured to be alpha(K*) = -0.04(-0.21)(+0.24).