We present a preliminary measurement of CP-violating parameters S and C from fits of the time-dependence of B0 meson decays to eta'K0L. The data were recorded with the BABAR detector at PEP-II and correspond to 232 10^6 BBbar pairs produced in e+e- annihilation through the Y(4S) resonance. By fitting the time-dependent CP asymmetry of the reconstructed B0 --> eta'K0L events, we find S = 0.60 +- 0.31 +- 0.04 and C = 0.10 +- 0.21 +- 0.03, where the first error quoted is statistical and the second is systematic. We also perform a combined fit using both eta'K0S and eta'K0L data, and find S = 0.36 +- 0.13 +- 0.03 and C = -0.16 +- 0.09 +- 0.02.
Categories: hep-ex