18 affect M s $_{12}$, but not Γ s $_{12}$, which is dominated by the CKM-favoured b → ccs tree-level decays. The leading contribution to Γ s 12 was obtained in [77, 83]. At present Γ s 12 is known to next-to- leading-order (NLO) in both Λ /m$_{b}$ [84] and α$_{s}$ ( m$_{b}$ ) [85–87], later in 2006 Nierste and Lenz [6] have improved the NLO calculation for ΔΓ$_{s}$ and updated the value for ΔΓ$_{s}$. In Fig. 3 the sensitivity of semileptonic CP asymmetry to SM4 is shown and we note an enhancement by a factor of 100 from its SM predicion of order 10 − $^{5}$. It could have a value − 0 . 4% and − 0 . 3% corresponding to maximum values of S$_{ψφ}$ for m$_{t}$ ′ = 400 and 600 GeV respectively. It is very useful to consider new physics effects in the observables which are either zero or highly suppressed in the SM as they constitute null test of the SM [88] . The reason is that any finite or large measurement of such an observable may signal the existence of new physics. The CP asymmetry in B → X$_{s}$ l $^{+}$l − is one such observable. In the SM, the CP asymmetry in B → X$_{s}$ l $^{+}$l − is ∼ 10 − 3 [89, 90]. In the SM, the only source of CP violation is the unique phase in the CKM quark mixing matrix. However in many possible extensions of the SM, there can be extra phases contributing to the CP asymmetry. Hence the CP C. CP asymmetry in B → X$_{s}$ l $^{+}$l − FIG. 3: Left panel shows the semileptonic CP asymmetry A$_{SL}$ as a function of | λ s t ′ | whereas in the right panel correlation between A$_{SL}$ and S$_{ψφ}$ is shown; red and blue region corresponds to m$_{t}$ ′ = 400 and 600 GeV respectively, the SM value of A$_{SL}$ (of order 10 − $^{5}$) is too close to zero to be visible in the plot whereas the SM value for S$_{ψφ}$ is − 0 . 04. -0.005 -0.004 -0.003 -0.002 -0.001  0  0.001 -1 -0.8 -0.6 -0.4 -0.2  0 A SL S -0.005 -0.004 -0.003 -0.002 -0.001  0  0.001  0  0.004  0.008  0.012  0.016  0.02 A SL | t’ $^{s}$|