Simple approach to fourth generation effects in B→X sℓ+ℓ- decay

Abstract

In a scenario in which fourth generation fermions exist, we study the effects of new physics on the differential decay width, forward-backward asymmetry, and the integrated branching ratio for B›Xsl +l-, decay with (l = e,µ). The prediction of the new physics on the mentioned quantities essentially differs from the standard model results in certain regions of parameter space; the enhancement of new physics on the abovementioned physical quantities can yield values as large as 2 times that of the SM predictions, from which present limits of experimental measurements of the branching ratio are spanned, and constraints of the new physics can be extracted. For the fourth generation CKM factor V*t'bVt's, we use ±102 and ±10-3 ranges, take into consideration the possibility of a complex phase where it may bring sizable contributions, and obtain no significant dependence on the imaginary part of the new CKM factor. For the above-mentioned quantities with a new family, deviations from the SM are promising and can be used as a probe of new physics.