Using a data set corresponding to an integrated luminosity of fac" title="Click to view the MathML source">3 fb−1, collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV, the effective lifetime in the fa2f9e69955ed5d96d05a"> decay mode, fa82c18f0a7" title="Click to view the MathML source">τeff, is measured to be
τeff=1.479±0.034 (stat)±0.011 (syst) ps.
Assuming CP conservation, fa82c18f0a7" title="Click to view the MathML source">τeff corresponds to the lifetime of the light mass eigenstate. This is the first measurement of the effective lifetime in this decay mode.