Charmless non-leptonic B s decays to P P , P V and V V final states in the pQCD approach AbstractWe calculate the CP-averaged branching ratios and CP-violating asymmetries of a number of two-body charmless hadronic decays B 0 s → P P, P V, V V in the perturbative QCD (pQCD) approach to leading order in α s (here P and V denote light pseudo-scalar and vector mesons, respectively). The mixinginduced CP violation parameters are also calculated for these decays. We also predict the polarization fractions of B s → V V decays and find that the transverse polarizations are enhanced in some penguin dominated decays such as B 0 s → K * K * , K * ρ. Some of the predictions worked out here can already be confronted with the recently available data from the CDF collaboration on the branching ratios for the

In this paper, we calculate the decay rate and CP asymmetry of the B s → π + π − decay in perturbative QCD approach with Sudakov resummation. Since none of the quarks in final states is the same as those of the initial B s meson, this decay can occur only via annihilation diagrams in the standard model. Besides the current-current operators, the contributions from the QCD and electroweak penguin operators are also taken into account. We find that (a) the branching ratio is about 4 × 10 −7 ; (b) the penguin diagrams dominate the total contribution; and (c) the direct CP asymmetry is small in size: no more than 3%; but the mixing-induced CP asymmetry can be as large as ten percent testable in the near future LHC-b experiments.

The weak decays of Λ b → Λ + γ and Λ b → Λ + l + l − are investigated in the Standard Model using light-cone sum rules approach. The higher twist distribution amplitudes of Λ baryon to the leading conformal spin are included in the sum rules for transition form factors. Our results indicate that the higher twist distribution amplitudes almost have no influences on the transition form factors retaining the heavy quark spin symmetry, while such corrections can result in significant impacts on the form factors breaking the heavy quark spin symmetry. Two phenomenological models (COZ and FZOZ) for the wave function of Λ baryon are also employed in the sum rules for a comparison, which can give rise to the form factors approximately five times larger than that in terms of conformal expansion. Utilizing the form factors calculated in LCSR, the physical observables like decay rate, polarization asymmetry and forward-backward asymmetry are analyzed for the decays of Λ b → Λγ, Λl + l − . I. INTRODUCTION Generally, new physics can be accessible through rare decays, where the contributions from the Standard Model (SM) are suppressed enough. Hence, such decays can provide an ideal platform to test the SM precisely as well as to bound new physics parameters stringently. Rare decays involving b → s flavor changing neutral current (FCNC), which are forbidden at the tree level in the standard model, can only be induced by Glashow-Iliopoulos-Maiani mechanism [1] via loop diagrams. The Cabibbo-Kobayashi-Maskawa (CKM) matrix [2, 3] elements can be determined quantitatively from b → s rare decays, B 0 s −B 0 s mixing [4] etc., which will test its unitarity under the requirement of the SM.It is well known that the inclusive decays are relatively robust theoretically, since the decay rate can be systematically and reasonably approximated by the decay of a free b quark into light quarks, gluons and photons; but the counterpart of experimental measurements are quite difficult. On the