A Two-Higgs-Doublet Model without Flavor-Changing Neutral Currents at Tree-Level


The flavor-changing neutral current (FCNC) problem at tree-level is a very critical defect of the two Higgs doublet extension of standard model (SM). In this article, a two-Higgs-doublet model (2HDM) in which such defects do not exist at all is to be demonstrated. The general pattern of matrix pairs which can be diagonalized simul-taneously by a same unitary transformation is proposed without extra constraints like symmetries or zeros in M matrices. Only an assumption of the hermiticity of mass matrices is employed in the derivation. With this assumption, number of parameters in the mass matrix of a specific fermion type is reduced from eighteen down to five. Eigenvalues and eigenvectors are analytically derived and it is surprising that unitary transformation matrix thus derived depends on only two parameters. It is a very general and elegant way to solve the tree-level FCNC problem radically and it includes previous similar models as special cases with specific parameter values.

Share and Cite:

Lin, C. (2019) A Two-Higgs-Doublet Model without Flavor-Changing Neutral Currents at Tree-Level. Journal of Modern Physics, 10, 35-42. doi: 10.4236/jmp.2019.101004.

Conflicts of Interest

The authors declare no conflicts of interest regarding the publication of this paper.


[1] Lee, T.D. (1973) Physical Review D, 8, 1226.
[2] Acosta, D. (2005) Physical Review Letters, 95, Article ID: 031801.
[3] Glashow, S.L. and Weinberg, S. (1977) Physical Review D, 15, 1958.
[4] Aoki, M., Kanemura, S., Tsumura, K. and Yagyu, K. (2009) Physical Review D, 80, Article ID: 015017.
[5] Pich, A. and Tuzon, P. (2009) Physical Review D, 80, Article ID: 091702. arXiv:0908.1554
[6] Branco, G.C., Ferreira, P., Lavoura, L., Rebelo, M., Sher, M., et al. (2012) Physics Reports, 516, 1-102.
[7] Diaz-Cruz, J.L., Noriega-Papaqui, R. and Rosado, A. (2004) Physical Review D, 69, Article ID: 095002.
[8] Fritzsch, H. (1978) Physics Letters B, 73, 317-322.
[9] Fritzsch, H. (1979) Nuclear Physics B, 155, 189-207.
[10] Cheng, T.P. and Sher, M. (1987) Physical Review D, 35, 3484.
[11] Liu, J. and Wolfenstein, L. (1987) Nuclear Physics B, 289, 1.
[12] Atwood, D., Reina, L. and Soni, A. (1997) Physical Review D, 55, 3156.
[13] Buras, A.J., Carlucci, M.V., Gori, S. and Isidori, G. (2010) JHEP, 1010, Article ID: 009. arXiv:1005.5310
[14] Hernandez-Sanchez, J., Moretti, S., Noriega-Papaqui, R. and Rosado, A. (2013) JHEP, 1307, Article ID: 044. arXiv:1212.6818
[15] Crivellin, A., Kokulu, A. and Greub, C. (2013) Physical Review D, 87, Article ID: 094031. arXiv:1303.2877
[16] Lin, C.L., Lee, C.E. and Yang, Y.W. (1988) Chinese Journal of Physics, 26, 180. arXiv:1703.07941
[17] Lee, C.E., Lin, C.L. and Yang, Y.W. (1990) Physical Review D, 42, 2355.
[18] Lin, C.L., Lee, C.E. and Yang, Y.W. (1994) Chinese Journal of Physics, 30, 41.
[19] Lin, C.L., arXiv:1308.6039, arXiv:1403.3482.
[20] Branco, G.C., Buras, A.J. and Gerard, J.M. (1985) Nuclear Physics B, 259, 306-330.

Copyright © 2021 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.