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CP violation and the fourth generation

Within the standard model with the 4th generation quarks b′ and t′ we have analyzed CP-violating flavor changing neutral current processes t→cX, b′→sX, b′→bX, t′→cX, and t′→tX, with X=H, Z, γ, g, by constructing and employing a global, unique fit for the 4th generation mass mixing matrix (CKM4) at 300≤mt′≤700  GeV. All quantities appearing in the CKM4 were subject to our fitting procedure. We have found that our fit produces the following CP partial rate asymmetry dominance: aCP(b′→s(H, Z ; γ, g))≃(94, 62 ; 47, 41)%, at mt′≃300, 350  GeV, respectively. From the experimental point of view the best decay mode, out of the above four, is certainly b′→sγ, due to the presence of the high energy single photon in the final state. We have also obtained relatively large asymmetry aCP(t→cg)≃(8-18)% for t′ running in the loops. There are fair chances that the 4th generation quarks will be discovered at LHC and that some of their decay rates will be measured. If b′ and t′ exist at energies we assumed, with well executed tagging, large aCP could be found too.

CP violation; 4th generation; top quark; FCNC

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