Charmless two body hadronic decays of Λ_b baryon

Using a theoretical framework based on the next-to-leading order QCD improved effective Hamiltonian, we have estimated the branching ratios and asymmetry parameters for the two body charmless nonleptonic decay modes of $\Lambda_b$ baryon i.e. $\Lambda_b \to p (\pi/\rho),~p(K/K^*)$ and $\Lambda (\pi/\rho)$, within the framework of generalized factorization. The nonfactorizable contributions are parametrized in terms of the effective number of colors, $N_c^{eff}$. So in addition to the naive factorization approach ($N_c^{eff}=3 $), here we have taken two more values for $N_c^{eff}$ i.e., $N_c^{eff}=2 $ and $\infty $. The baryonic form factors at maximum momentum transfer ($ q_m^2 $) are evaluated using the nonrelativistic quark model and the extrapolation of the form factors from $q_m^2$ to the required $q^2$ value is done by assuming the pole dominance. The obtained branching ratios for $\Lambda_b \to p\pi, ~pK$ processes lie within the present experimental upper limit .