Fourth-generation effect on CP violation in B-->K phi decays.

Abstract

CP-violating asymmetries in the B\ensuremath{\rightarrow}K\ensuremath{\varphi} decays are studied in the four-generation model. The absorptive part in the penguin amplitude leads to the CP-violating asymmetry in the ${B}_{U}^{\ifmmode\pm\else\textpm\fi{}}$\ensuremath{\rightarrow}${K}^{\ifmmode\pm\else\textpm\fi{}}$\ensuremath{\varphi} decays, which could be as large as \ifmmode\pm\else\textpm\fi{}15% in the four-generation model, although it is at most a few percent in the three-generation model. The asymmetry between the ${B}_{d}^{0}$\ensuremath{\rightarrow}${K}_{S}^{0}$\ensuremath{\varphi} and B${\ifmmode\bar\else\textasciimacron\fi{}}_{d}^{0}$\ensuremath{\rightarrow}${K}_{S}^{0}$\ensuremath{\varphi} decays is also expected to be \ifmmode\pm\else\textpm\fi{}10% on \ensuremath{\Upsilon}(4S) through the penguin absorptive part with the contribution of the fourth-generation quark.