Precise Measurement of the K+K- Lifetime Ratio

In this paper the details of a previously reported precise measurement of the K⁺K^- lifetime ratio are described. Using a separated beam at the Brookhaven AGS, we have counted the fraction of 1.6- and 2.0-GeV/c K mesons surviving at distances up to 2000 in. The result of the measurement yields τ(K⁺)τ(K^-)-1=-0.00090+/-0.00078, indicating no violation of the CPT theorem. No evidence for deviations from an exponential decay law or for the existence of long-lived K mesons was found. The upper limit for any long-lived K mesons in the beam is 3×10^-3 at the 90% confidence level.