2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/193283This study investigates the influence of the fourth generation quarks on the double lepton polarizations in Λ_b --> Λ\ell^+ \ell^- decay by taking |V^\ast_{t's}V_{t'b}|= 0.005,0.01,0.02,0.03 with phase \{60^\circ,90^\circ,120^\circ\}. We will try to obtain a constrain on the mass of the 4th generation top like quark t', which is consistent with the $b--> s\ell^+\ell^- rate . With the above mentioned parameters, we will try to show that the double lepton(muon, tau) polarizations are quite sensitive to the existence of fourth generation. It can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation quarks(t', b') via its indirect manifestations in loop diagrams.36 pages, 33 figuresHigh Energy Physics - Phenomenologytext