Electroweak monopoles and the electroweak phase transition

Abstract

We consider an isolated electroweak monopole solution within the Standard Model with a nonlinear BornInfeld extension of the hypercharge gauge field. Monopole (and dyon) solutions in such an extension are regular and their masses are predicted to be proportional to the Born-Infeld mass parameter. We argue that cosmological production of electroweak monopoles may delay the electroweak phase transition and make it more strongly first order for monopole masses M 9.3 · 10 3 TeV, while the nucleosynthesis constraints on the abundance of relic monopoles impose the bound M 2.3 · 10 4 TeV. The monopoles with a mass in this shallow range may be responsible for the dynamical generation of the matter-antimatter asymmetry during the electroweak phase transition.

Weak-U(1) × strong-U(1) effective gauge field theories and electron-monopole scattering

“…We should stress though that the emergence of the strong U(1) interactions from microscopic considerations in concrete composite monopole models existing in the current literature [5,7,12,13] is still not understood. It might be possible that the very existence of a magnetic pole implies automatically such interactions, as an effective way of describing the monopole quantum fluctuations.…”

“…The latter regime violates the unitarity bound (41), which is possible in the case of composite monopoles. As mentioned in the introduction, these are the only type of known solutions of field theories of phenomenological interest so far [5,7,12,13]. Thus, the effective field theory developed here can only be associated with composite monopoles/dyons, not necessarily restricted to the aforementioned types, but also encompassing new composite monopole/dyon solutions that may exist in beyond the standard model physics.…”

“…As we have discussed in the introduction, one may obtain the differential cross section for non-relativistic electronmonopole scattering at small angles using quantum mechanical treatment, leading to the expression (11), which scales with the relative momentum p = µv of the incident matter particle (in the frame where the heavy monopole is initially at rest) as 1/p 2 instead of the traditional 1/p 4 of the conventional Ruhterford scattering differential cross section (13) between charged matter particles. As already mentioned previously, upon invoking electric-magnetic duality, one may obtain the Rutherford scattering formula from (11), by replacing the monopole magnetic coupling with an effective velocity(β)-dependent magnetic coupling, (14), (15).…”

“…At this point we make some important remarks, which relate to the fact that the above effective field theory approach can only describe composite monopoles, like the ones that exist currently as topological soliton solutions of several field theories of phenomenological relevance [5,7,12,13], as discussed in the introduction of the article. This becomes clear by noticing that, because of the presence of the transmutation scale k, the wave function renormalization Z (63) for the monopole fermion can, and in fact it does for k → k 0 , become smaller than unity.…”

“…Recently, though, it was observed that finite energy monopoles of the type proposed in [11] can characterise extensions of the Standard Model, with either appropriate non-minimally coupled Higgs and hypercharge sectors [12], or higher-derivative extensions of the hypercharge sector, for instance in a (string-inspired) Born-Infeld configuration [13]. Such monopole/dyon solutions could have masses accessible to the scales of current or future colliders.…”