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Precision measurement of the ratio BR(K_s→ π^+ π^- e^+ e^- )BR (K_L→π^+ π^- π_D^0)

Abstract : The KS→π+π−e+e− decay mode was investigated using the data collected in 2002 by the NA48/1 collaboration. With about 23 k KS→π+π−e+e− events and 59 k View the MathML source normalization decays, the KS→π+π−e+e− branching ratio relative to the View the MathML source one was determined to be View the MathML source. This result was used to set the upper limit |gE1/gBR|<3.0 at 90% CL on the presence, in the decay amplitude, of an E1 direct emission (gE1) term relative to the dominant inner bremsstrahlung (gBR) term. The CP-violating asymmetry View the MathML source in the View the MathML source distribution of KS→π+π−e+e− events, where phi is the angle between the π+π− and the e+e− decay planes in the kaon centre of mass, was found to be View the MathML source, consistent with zero. These results are in good agreement with a description of the KS→π+π−e+e− decay amplitude dominated by the CP-even inner bremsstrahlung process.
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Contributor : Danielle Cristofol <>
Submitted on : Wednesday, October 13, 2010 - 8:51:38 AM
Last modification on : Tuesday, March 30, 2021 - 3:17:49 AM

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J.R. Batley, G.E. Kalmus, C. Lazzeroni, D.J. Munday, M. Patel, et al.. Precision measurement of the ratio BR(K_s→ π^+ π^- e^+ e^- )BR (K_L→π^+ π^- π_D^0). Physics Letters B, Elsevier, 2011, 694, pp.301-309. ⟨10.1016/j.physletb.2010.10.008⟩. ⟨in2p3-00525873⟩



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