First determination of the CP content of D → π + π ? π + π ? and updated determination of the CP contents of D → π + π ? π 0 and D → K + K ? π 0

摘要

Quantum-correlated ψ ( 3770 ) → D D ˉ decays collected by the CLEO-c experiment are used to perform a first measurement of F + 4 π , the fractional CP -even content of the self-conjugate decay D → π + π ? π + π ? , obtaining a value of 0.737 ± 0.028 . An important input to the measurement comes from the use of D → K S 0 π + π ? and D → K L 0 π + π ? decays to tag the signal mode. This same technique is applied to the channels D → π + π ? π 0 and D → K + K ? π 0 , yielding F + π π π 0 = 1.014 ± 0.045 ± 0.022 and F + K K π 0 = 0.734 ± 0.106 ± 0.054 , where the first uncertainty is statistical and the second systematic. These measurements are consistent with those of an earlier analysis, based on CP -eigenstate tags, and can be combined to give values of F + π π π 0 = 0.973 ± 0.017 and F + K K π 0 = 0.732 ± 0.055 . The results will enable the three modes to be included in a model-independent manner in measurements of the unitarity triangle angle γ using B ? → D K ? decays, and in time-dependent studies of CP violation and mixing in the D 0 D ˉ 0 system.