First measurement of the $π^+π^-$ atom lifetime

The DIRAC collaboration

doi:10.1016/j.physletb.2005.05.045

paper

First measurement of the $π^{+} π^{-}$ atom lifetime

arXiv:hep-ex/0504044 · doi:10.1016/j.physletb.2005.05.045

Abstract

The goal of the DIRAC experiment at CERN (PS212) is to measure the $π^{+} π^{-}$ atom lifetime with 10% precision. Such a measurement would yield a precision of 5% on the value of the $S$ -wave $π π$ scattering lengths combination $∣ a_{0} - a_{2} ∣$ . Based on part of the collected data we present a first result on the lifetime, $τ = [2.9 1_{- 0.62}^{+ 0.49}] \times 1 0^{- 15}$ s, and discuss the major systematic errors. This lifetime corresponds to $∣ a_{0} - a_{2} ∣ = 0.26 4_{- 0.020}^{+ 0.033} m_{π}^{- 1}$ .

18 pages, 6 figures

First measurement of the π+π− atom lifetime

Abstract

First measurement of the $π^{+} π^{-}$ atom lifetime