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Measurement of the Ratio $\Gamma(K_L \to \pi^+ \pi^-)/\Gamma(K_L \to \pi\pm e \mp\nu)$ and Extraction of the CP Violation Parameter $|\eta+-|$

A. Bevan R. S. Dosanjh T. J. Gershon B. Hay G. E. Kalmus C. Lazzeroni D. J. Munday E. Olaiya M. A. Parker T. O. White S.A. Wotton G. Barr G. Bocquet A. Ceccucci T. Cuhadar-Dnszelmann D. Cundy G. d'Agostini N. Doble V. Falaleev L. Gatignon A. Gonidec B. Gorini G. Govi P. Grafstrm O. W Kubischta A. Lacourt A. Norton S. Palestini B. Panzer-Steindel H. Taureg M. Velasco H. Wahl C. Cheshkov P. Z. Khristov V. Kekelidze L. Litov D. T. Madigozhin N. Molokanova Yu Potrebenikov S. Stoynev A. Zinchenko I. Knowles V. Martin R. Sacco A. Walker M. Contalbrigo P. Dalpiaz J. Duclos P. L. Frabetti A. Gianoli M. Martini F. Petrucci M. Savrié A. Bizzeti M. Calvetti G. Collazuol G. Graziani E. Iacopini M. Lenti G. Ruggiero M. Veltri H. G. Becker K. Eppard M. Eppard H. Fox A. Kalter K. Kleinknecht U. Koch L. Köpke P. Lopes da Silva O. P Marouelli I. Pellmann A. Peters B. Renk S.A. Schmidt V. Schönharting Yu Schué R. Wanke A. Winhart M. Wittgen J.C. Chollet 1 L. Fayard 1 L. Iconomidou-Fayard 1 J. Ocariz 1 G. Unal 1 Isabelle Wingerter-Seez 1 G. Anzivino P. Cenci E. Imbergamo P. Lubrano A. Mestvirishvili A. Nappi M. Pepé M. Piccini L. Bertanza R. Carosi R. Casali C. Cerri M. Cirilli F. Costantini R. Fantechi S. Giudici I. Mannelli G. Pierazzini M. Sozzi J.B. Chèze 2 J. Cogan 2 M. de Beer 2 P. Debu 2 A. Formica 2 R. Granier de Cassagnac 2 E. Mazzucato 2 B. Peyaud 2 R. Turlay 2 B. Vallage 2 R. Bernhard M. Holder A. Maier M. Ziolkowski R. Arcidiacono C. Biino N. Cartiglia F. Marchetto E. Menichetti N. Pastrone J. Nassalski E. Rondio M. Szleper W. Wislicki S. Wronka H. Dibon G. Fischer M. Jeitler M. Markytan I. Mikulec G. Neuhofer M. Pernicka A. Taurok L. Widhalm
Abstract : We present a measurement of the ratio of the decay rates Gamma(KL -> pi+ pi-)/Gamma(KL -> pi e nu), denoted as Gamma(K2pi)/Gamma(Ke3). The analysis is based on data taken during a dedicated run in 1999 by the NA48 experiment at the CERN SPS. Using a sample of 47000 K2pi and five million Ke3 decays, we find Gamma(K2pi)/Gamma(Ke3) = (4.835 +- 0.022(stat) +- 0.016(syst)) x 10^-3. From this we derive the branching ratio of the CP violating decay KL -> pi+ pi- and the CP violation parameter |eta+-|. Excluding the CP conserving direct photon emission component KL -> pi+ pi- gamma, we obtain the results BR(KL -> pi+ pi-) = (1.941 +- 0.019) x 10^-3 and |eta+-| = (2.223 +- 0.012) x 10^-3.
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Submitted on : Thursday, April 19, 2007 - 3:48:25 PM
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A. Bevan, R. S. Dosanjh, T. J. Gershon, B. Hay, G. E. Kalmus, et al.. Measurement of the Ratio $\Gamma(K_L \to \pi^+ \pi^-)/\Gamma(K_L \to \pi\pm e \mp\nu)$ and Extraction of the CP Violation Parameter $|\eta+-|$. Physics Letters B, Elsevier, 2007, 645, pp.26-35. ⟨10.1016/j.physletb.2006.11.071⟩. ⟨in2p3-00142530⟩

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