High statistics measurement of Ke4 decay properties

S. Pislak , R. Appel , G.S. Atoyan , B. Bassalleck , D.R. Bergman , N. Cheung , S. Dhawan , H. Do

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J. Egger S. Eilerts H. Fischer W. Herold V.V. Issakov H. Kaspar D.E. Kraus D.M. Lazarus P. Lichard J. Lowe J. Lozano H. Ma W. Majid A.A. Poblaguev P. Rehak A. Sher Aleksey Sher J.A. Thompson P. Tru\"ol M.E. Zeller (E865 collaboration at Brookhaven National Laboratory)

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classification ✦ hep-ex

keywords beendecaymeasurementpi-pi-scatteringaccuracyalternateanalyticitybackground

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We report experimental details and results of a new measurement of the decay K+ -> pi+pi-e+nue (Ke4}. A sample of more than 400,000 Ke4 events with low background has been collected by Experiment 865 at the Brookhaven Alternate Gradient Synchrotron. From these data, the branching ratio (4.11+-0.01+-0.11)*10**(-5) and the pi-pi invariant mass dependence of the form factors F, G, and H of the weak hadronic current as well as the phase shift difference delta00-delta11 for pi-pi-scattering were extracted. Using constraints based on analyticity and chiral symmetry, a new value with considerably improved accuracy for the s-wave pi-pi-scattering length a00 has been obtained also: a00=0.216+-0.013 (stat.)+-0.002(syst.)+-0.002(theor.).

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High statistics measurement of Ke4 decay properties

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