Top and Higgs flavor changing neutral couplings in two Higgs doublets model
- Physics Division, National Center for Theoretical Sciences, P. O. Box 2-131 Hsinchu, Taiwan 300 (China)
We study various channels of top and Higgs flavor changing neutral couplings in the two Higgs doublet model with natural flavor conservation (2HDM-I and 2HDM-II). We update known results about t{yields}c{gamma},cZ,cg and comment on t{yields}ch{sup 0}. The decays t{yields}ch{sup 0} as well as {l_brace}h{sup 0},H{sup 0}{r_brace}{yields}tc are sensitive both to the bottom Yukawa coupling as well as to the trilinear scalar couplings h{sup 0}H{sup +}H{sup -} and H{sup 0}H{sup +}H{sup -}. After imposing unitarity constraints as well as vacuum stability conditions on scalar sector parameters, in 2HDM-II we found that for large tan{beta} > or approx. 40 and rather light charged Higgs mass M{sub H{+-}} > or approx. 150 GeV, the maximum values allowed for Br(t{yields}ch{sup 0}), Br(H{sup 0}{yields}tc), and Br(h{sup 0}{yields}tc) are: 8x10{sup -5}, 10{sup -3}, and 10{sup -4} respectively. For charged Higgs mass in the range [200,300] GeV, which can accommodate B{yields}X{sub s}{gamma} constraint if one takes into account large theoretical uncertainties, the branching ratio of both H{sup 0}{yields}tc and h{sup 0}{yields}tc can still be slightly larger than 10{sup -5}. For A{sup 0}{yields}tc, its branching ratio is smaller than {approx_equal}10{sup -7} in both 2HDM-I and 2HDM-II. We study also the top-charm associated production at e{sup +}e{sup -} colliders and its {gamma}{gamma} option as well as at muon colliders. It is found that the cross section of {gamma}{gamma}{yields}tc can be of the order 0.01{yields}0.1 fb near threshold region, while the cross section of e{sup +}e{sup -}{yields}tc is well below 10{sup -2} fb. The situation is slightly better for muon colliders where a few fb cross section can be reached for large tan{beta} and low center-of-mass energy {radical}(s) < or approx. 500 GeV.
- OSTI ID:
- 20713678
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 72, Issue 7; Other Information: DOI: 10.1103/PhysRevD.72.075016; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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