We measure the time-dependent $C\!P$ violation parameters in $B^{ 0} \to K^{ 0}_{ S}K^{ 0}_{ S}K^{ 0}_{ S}$ decays using $772 \times 10^6$ $B { \mkern 1.5mu\overline{ \mkern-1.5mu B \mkern-0.1mu}\mkern 0.1mu}$ pairs collected at the $\Upsilon (4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The obtained mixing-induced and direct $C\!P$ asymmetries are $-0.71 \pm 0.23~{ \rm(stat)} \pm 0.05~{ \rm(syst)}$ and $0.12 \pm 0.16~{ \rm(stat)} \pm 0.05~{ \rm(syst)}$, respectively. These values are consistent with the Standard Model predictions. The significance of $C\!P$ violation differs from zero by 2.5 standard deviations.
Categories: hep-ex