We estimate the CP asymmetry ACP(q2) in the decays B→Xsμ+μ- and B→Xdμ+μ- in the standard model (SM) with an additional fourth generation. We use a parametrization that allows us to explore the complete parameter space of the 4×4 quark mixing matrix, and constrain these parameters from the current data on B decays. We find that the enhancement in ACP(q2) depends strongly on the mass of the t′, the up-type quark in the fourth generation. For mt′ around 400 GeV, the CP asymmetry in the high-q2 region (q2>14.4GeV2) can be enhanced by more than an order of magnitude for B→Xsμ+μ- and up to a factor of 6 for B→Xdμ+μ-. There is no enhancement in the low-q2 region (1<q2<6GeV2). With increasing mt′, ACP(q2) in the high-q2 (low-q2) region first decreases (increases) and then saturates at a value a few times the SM prediction. In the high-q2 region of B→Xsμ+μ-, this saturation value may be up to 25 times the SM expectation. © 2009 The American Physical Society.

Ashutosh Kumar Alok

Department of Physics

IIT Jodhpur

A. Dighe

S. Ray

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Journal	Physical Review D - Particles, Fields, Gravitation and Cosmology
ISSN	15507998