physlettb754_349.pdf 274 KB
波場 直之 Graduate School of Science and Engineering, Shimane University
石田 裕之 Graduate School of Science and Engineering, Shimane University
岡田 宜親 Department of Physics and Astronomy, University of Alabama
山口 雄也 Graduate School of Science and Engineering, Shimane University : Department of Physics, Faculty of Science, Hokkaido University
We suggest the so-called bosonic seesaw mechanism in the context of a classically conformal U(1)_ltB-Lgt extension of the Standard Model with two Higgs doublet fields. The U(1)_ltB-Lgt symmetry is radiatively broken via the Coleman-Weinberg mechanism, which also generates the mass terms for the two Higgs doublets through quartic Higgs couplings. Their masses are all positive but, nevertheless, the electroweak symmetry breaking is realized by the bosonic seesaw mechanism. Analyzing the renormalization group evolutions for all model couplings, we find that a large hierarchy among the quartic Higgs couplings, which is crucial for the bosonic seesaw mechanism to work, is dramatically reduced toward high energies. Therefore, the bosonic seesaw is naturally realized with only a mild hierarchy, if some fundamental theory, which provides the origin of the classically conformal invariance, completes our model at some high energy, for example, the Planck scale. We identify the regions of model parameters which satisfy the perturbativity of the running couplings and the electroweak vacuum stability as well as the naturalness of the electroweak scale.
Physics letters. B
© 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.