Simple approach to fourth generation effects inB→Xsl+

Abstract

In a scenario in which fourth generation fermions exist, we study effects of new physics on the differential decay width, forward-backward asymmetry and integrated branching ratio for B → Xsℓ + ℓ − decay with (ℓ = e, µ). Prediction of the new physics on the mentioned quantities essentially differs from the Standard Model results, in certain regions of the parameter space, enhancement of new physics on the above mentioned physical quantities can yield values as large as two times of the SM predictions, whence present limits of experimental measurements of branching ratio is spanned, contraints of the new physics can be extracted. For the fourth generation CKM factor V * t ′ b V t ′ s we use ±10 −2 and ±10 −3 ranges, take into consideration the possibility of a complex phase where it may bring sizable contributions, obtained no significant dependency on the imaginary part of the new CKM factor. For the above mentioned quantities with a new family, deviations from the SM are promising, can be used as a probe of new physics.

Double Lepton Polarization in $Λ_b -->Λl^+ l^-$ Decay in the Standard Model with Fourth Generations Scenario

“…On boosting the vectors defined by Eqs. (30,31) to the c.m. frame of the ℓ − ℓ + system only the longitudinal vector will be boosted, whilst the other two vectors remain unchanged.…”