Unparticle-Higgs Mixing: MSW Resonances, See-saw Mechanism and Spinodal Instabilities

TL;DR

This paper explores the mixing of unparticles with the Higgs field, revealing MSW resonances, spinodal instabilities, and implications for inflationary cosmology, with novel effects arising from unparticle noncanonical behavior.

Contribution

It introduces a new framework for unparticle-Higgs mixing, demonstrating MSW resonances, spinodal instabilities, and potential impacts on inflation and cosmic perturbations.

Findings

Identifies two MSW resonances at different momenta.

Unparticle modes exhibit spinodal instabilities and large expectation values.

Mixing influences slow-roll parameters, favoring a red scalar spectrum.

Abstract

Motivated by slow-roll inflationary cosmology we study a scalar unparticle weakly coupled to a Higgs field in the broken symmetry phase. The mixing between the unparticle and the Higgs field results in a seesaw type matrix and the mixing angles feature a Mikheyev-Smirnov-Wolfenstein (MSW) effect as a consequence of the unparticle field being noncanonical. We find two (MSW) resonances for small and large spacelike momenta. The unparticlelike mode features a nearly flat potential with spinodal instabilities and a large expectation value. An effective potential for the unparticlelike field is generated from the Higgs potential, but with couplings suppressed by a large power of the small seesaw ratio. The dispersion relation for the Higgs-like mode features an imaginary part even at "tree level" as a consequence of the fact that the unparticle field describes a multiparticle continuum. Mixed unparticle-Higgs propagators reveal the possibility of oscillations, albeit with short coherence lengths. The results are generalized to the case in which the unparticle features a mass gap, in which case a low energy MSW resonance may occur for lightlike momenta depending on the scales. Unparticle-Higgs mixing leads to an effective unparticle potential of the new-inflation form. Slow-roll variables are suppressed by seesaw ratios and the anomalous dimensions and favor a red spectrum of scalar perturbations consistent with cosmic microwave background data.