The exact solution for neutrino mass matrix of the Zee-Babu model is derived. The tribimaximal mixing imposes the conditions on the Yukawa couplings, from which the normal mass hierarchy is preferred. The derived conditions give a possibility of maximal CP violation in the neutrino sector. | Communications in Physics, Vol. 23, No. 3 (2013), pp. 193-201 ON YUKAWA COUPLINGS IN THE ZEE-BABU MODEL HOANG NGOC LONG Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi, Vietnam VO VAN VIEN Department of Physics, Tay Nguyen University, 587 Le Duan, Buon Ma Thuot, Vietnam Received 08 July 2013; Accepted for publication 20 July 2013 Abstract. The exact solution for neutrino mass matrix of the Zee-Babu model is derived. The tribimaximal mixing imposes the conditions on the Yukawa couplings, from which the normal mass hierarchy is preferred. The derived conditions give a possibility of maximal CP violation in the neutrino sector. I. INTRODUCTION Nowadays, particle physicists are attracted by two exciting subjects: Higgs and neutrino physics. The neutrino mass and mixing are the first evidence of the beyond Standard Model. Many experiments show that neutrinos have tiny masses and their mixing is still mysterious [1]. Recent data are a clear sign of rather large value θ13 [2]. The discovery of the long-waiting Higgs boson at around 125 GeV [3] opened a new chapter in particle physics. It is essential for us to determine which model the discovered Higgs boson belongs to? For this aim, the diphoton decay of the Higgs boson plays very important role. It is expected that new physics might enter here to modify the standard model (SM) Higgs property. Within the above mentioned reasons, the search of extended model coinciding with the current data on neutrino and Higgs physics is one of top priorities. In our opinion, the model with simplest particle content is preferred. In the SM, neutrinos are strictly massless. For neutrino mass, it was first pointed out by Zee in Ref. [4] in which new scalars are added in the Higgs sector with neutrino masses induced at the one-loop level. After that a two-loop scenario called Zee-Babu model [5] was proposed. The Zee-Babu model [4–6] with just two additional charged Higgs bosons (h− , k−− ) .
