Spontaneous Symmetry Breaking through Mixing
نویسندگان
چکیده
We discuss a model, in which the negative mass square needed in the Higgs mechanism is generated by mixing with a heavy scalar. We have two scalar doublets in the standard model. Phenomenological properties of the heavy new scalar are discussed. The heavy scalar can be detected by the LHC. In the Standard Model (SM) the masses of the Wand Z-bosons and of the fermions (leptons and quarks) are introduced by the mechanism of spontaneous symmetry breaking (”Higgs mechanism”). It is assumed that the squared mass term of the scalar particle is negative. This, together with the φ self interaction of the scalar bosons leads to a non-zero vacuum expectation value. The masses of the Wand Z-bosons are spontaneously generated via the gauge interaction, and the masses of the fermions appear due to their Yukawa-type interactions with the scalar. No prediction can be made about the fermion masses, since they depend on the Yukawa coupling constants, which are free parameters. The negative mass square of the scalar boson is rather peculiar and looks to us like an ad-hoc assumption, not explaining why the electroweak gauge symmetry is broken. In this paper we would like to propose a possible underlying mechanism, able to generate the imaginary Higgs mass (see also [1]) at an energy scale testable at the LHC. We assume that there is a massless scalar which mixes (seesaw like) with a heavy scalar. Through the mixing a negative mass for the scalar is introduced in a natural way. As a result of the mixing the spontaneous symmetry breaking arises as in the Standard Model. For a long time, the seesaw mechanism has been widely studied to generate light neutrino masses [2] as well as to explain the mass hierarchies in the whole fermion sector [3]. Instead, the idea of applying this mechanism to the scalar sector of the SM beside incorporating new degrees of freedom is quite new and recieved increasing interest over the last years [4]. The scalar sector of this model is given by the following Lagrange density: Lsc. = D μ (
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