Fourth generation quark masses and KM phenomenology from a fritzsch mass matrix
1986; Elsevier BV; Volume: 271; Issue: 3-4 Linguagem: Inglês
10.1016/s0550-3213(86)80023-2
ISSN1873-1562
AutoresMichael Shin, R. Sekhar Chivukula, J. M. Flynn,
Tópico(s)High-Energy Particle Collisions Research
ResumoFrom the patterns of the quark mass matrices observed in two and three generations of quarks, a plausible form of the quark mass matrix with phases (of multiples of ½ π) is proposed for four generations of quarks. This allows the determination of the entire 4 × 4 KM matrix as a function of just two unknowns (mb′ and mt′), and the allowed mass ranges of the 4th generation quarks (which we call b′ and t′) are obtained from the present constraints on the KM matrix in the first 3-generation sector. The possibility of a light 4th generation quark (mb′ < 45 GeV) is shown, while the most likely bounds on the masses are mb′ ⩾ 32 GeV, mt′ ⩾ 82 GeV for the "bag" factor |BK| > 0.1. It is pointed out that UA1's t-quark data may also contain the b′-quark with mb′ ⩽ 50 GeV, and in this case, mt′ is shown to be bounded from above, mt′ ⩽ 190 GeV. Some low-energy phenomenology such as B0 − B̄0 mixing and CP violation, in which the effects of the 4th generation quarks may be observable, are also considered. The main result is that the mixing parameter Rodd for B0d − B̄0d is 5–6 times larger than in the 3-generation case and may be observable (Rodd ∼ 10%) if the uncertainties in the parameters used are taken into account. The CP-violating parameter l± is shown to be too small to be observed (O(10−4−10−6)) for both B0d and Bs0, while the mixing parameter Rodd for Bs0 − B̄s0 is shown to be definitely observable (Rodd > 50%) regardless of the 4th generation quark masses.
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