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Measurement of $k^0 _{\mu 3}$ form factors (2006)

Abstract
This paper reports on a new high precision measurement of the form factors of the $\rm K_{L}\rightarrow~\pi^{\pm}~\mu^{\mp}~\nu_{\mu}$} decay. The data sample of about 2.3X10^6 events was recorded in 1999 by the NA48 experiment at CERN. Studying the Dalitz plot density we measured a linear, $\lambda^{'}_{+} = (16.8\pm 2.3_{stat} \pm 2.4_{syst})\times 10^{-3}$, and a quadratic, $\lambda^{''}_{+} = (4.0\pm 1.0_{stat} \pm 1.0_{syst})\times 10^{-3}$ term in the power expansion of the vector form factor. No evidence was found for a second order term for the scalar form factor; the linear slope was determined to be $\lambda_{0} = (9.1\pm 1.1_{stat} \pm 0.8_{syst})\times 10^{-3}$. \noindent Using a linear fit our results were: $\lambda_{+} = (26.1\pm 0.6_{stat} \pm 0.8_{syst} )\times 10^{-3}$ and, $\lambda_{0} = (12.6\pm 0.7_{stat} \pm 1.0_{syst} )\times 10^{-3}$.\\ \noindent A pole fit of the form factors yields: $m_V = ( 915 \pm 10_{stat} \pm 17_{syst} )$ MeV/c$^2$ and $m_S = (1348 \pm 43_{stat} \pm 53_{syst} )$ MeV/c$^2$.

Publication details
Download http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=phep-2006-033
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=hep-ex&id=0703002
Repository CERN Document Server (Switzerland)
Keywords Particle Physics - Experimental Results
Language eng