Sommerfeld Enhancement with Triplet Fermions

Tejas, S (2021) Sommerfeld Enhancement with Triplet Fermions. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Tejas S (16MS003)) 16MS003_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (700kB)

Abstract

Sommerfeld effect is an elementary effect seen in non-relativistic quantum mechanics where the presence of a central potential gives rise to enhancements in scattering cross sections and is an important tool for indirect searches of dark matter(DM). There has been enough evidences to show the existence of the dark matter(DM), but not much is known about the characteristics of DM. Prime candidate for the cold non-relativistic non-baryonic dark matter is the Weakly Interacting Massive Particles(WIMPs). This is a promising candidate, as it can naturally explain the DM abundances of our universe by its thermal production mechanism[29]. Also, it has been known theoretically that the dark matter WIMPs cannot be standard model(SM) particles. In this thesis, we construct a new fermion sector as an extension to the SM, the triplet fermion. This model is inspired from the wino like annihilations, type III see saw mechanism in neutralino mass production and vector-like unificon models. As we will show, the neutral component of the triplet fermion will be the DM candidate and has weak interactions with gauge bosons and undergoes pair annihilations. In the non-relativistic case, the pair annihilation sees a non-perturbative effect with large enhancement factors(Sommerfeld enhancement factor) affecting the cross section. We have demonstrated the profound impact of Sommerfeld enhancement in the U(1) scenarios dealing with Coulomb and Yukawa potentials[4, 5]. Then, we have presented a systematic approach which takes into account of the non-perturbative effect in our triplet fermion case of DM annihilations, having weak interactions with gauge bosons similar to the case of the Electroweak Interacting Massive particles(EWIMPs). Through this approach, we have obtained the potential that governs such weak interactions of the triplet fermions and then compared it with the EWIMP case. The potential we have obtained can be further used to study the indirect searches of DM, such as can be used to find the gamma-ray flux signal strength. It can also be used to study the relic density implications such as impact on abundance of DM.

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