Measurement of the πk atom lifetime and the πk scattering length

Abstract

After having announced the statistically significant observation (5.6σ) of the new exotic πK atom, the DIRAC experiment at the CERN proton synchrotron presents the measurement of the corresponding atom lifetime, based on the full πK data sample: τ=(5.5-2.8+5.0)×10-15 s. By means of a precise relation (≈1%) between atom lifetime and scattering length, the following value for the S-wave isospin-odd πK scattering length a0-=13(a1/2-a3/2) has been derived: |a0-|=(0.072-0.020+0.031)Mπ-1.