Studying a Two-Component Dark Matter Model: An Introduction

Table of Links

Acknowledgements

1 Introduction to thesis

1.1 History and Evidence

1.2 Facts on dark matter

1.3 Candidates to dark matter

1.4 Dark matter detection

1.5 Outline of the thesis

2 Dark matter through ALP portal and 2.1 Introduction

2.2 Model

2.3 Existing constraints on ALP parameter space

2.4 Dark matter analysis

2.5 Summary

3 A two component dark matter model in a generic 𝑈(1)𝑋 extension of SM and 3.1 Introduction

3.2 Model

3.3 Theoretical and experimental constraints

3.4 Phenomenology of dark matter

3.5 Relic density dependence on 𝑈(1)𝑋 charge 𝑥𝐻

3.6 Summary

4 A pseudo-scalar dark matter case in 𝑈(1)𝑋 extension of SM and 4.1 Introduction

4.2 Model

4.3 Theoretical and experimental constraints

4.4 Dark Matter analysis

4.5 Summary

5 Summary

Appendices

A Standard model

B Friedmann equations

C Type I seasaw mechanism

D Feynman diagrams in two-component DM model

Bibliography

3 A two component dark matter model in a generic 𝑈(1)𝑋 extension of SM

In this chapter, we study a two-component DM model interacting with SM via Higgs and Z portals. The results are based on the work: Arindam Das, Shivam Gola, Sanjoy Mondal, Nita Sinha, "Two-Components Scalar and Fermionic Dark Matter candidates in a generic U(1)𝑋 model, Phys.Lett.B 2022.137117”.

3.1 Introduction

Underpinning the origin of neutrino mass and elucidating the nature of DM would constitute a major step forward in particle physics. Several simple extensions of the SM that can account for the DM have already been studied [136–143]. In these models, the SM particle content is extended by additional fields, and a discrete symmetry is usually introduced to guarantee the stability of the DM particle in cosmological scale. In recent years, a class of models has been proposed to incorporate the neutrino mass generation and the existence of DM in a unified framework. Motivated by this, people have studied well-motivated BSM framework based on the gauged 𝑈(1)𝑋 model [144–146]. The most intriguing aspect of this model is that including three generations of right-handed neutrinos, as in the type-I seesaw process for creating light neutrino masses, is no longer an option, but emerges as the simplest solution to eliminate the gauge and mixed gauge-gravity anomalies [147]. The scalar DM can be inherently stable in such models due to its 𝑈(1)𝑋 charge, but the fermionic DM cannot be realized in the simplest 𝑈(1)𝑋 model. Additional discrete symmetries can be introduced, which can stabilize one of the right-handed neutrinos to play the role of DM, while the other two neutrinos participate in the type I seesaw process to generate the required light neutrino masses and flavor mixing. Also, there are many models proposed in the literature, where neutrino mass generation is intimately connected with DM [148–153]. In these types of models, DM is a mediator of neutrino mass generation.

A single-particle DM model may not be sufficient to account for the relic density of DM observed in the universe. Many such models face strong constraints from direct detection experiments and other observations. Therefore, it is reasonable to consider multi-particle DM scenarios, where two or more particles contribute to the DM abundance. [24,62,126]. Multi-component DM refers to a situation in which two or more particles contribute to the measured DM density. This has been already studied in many BSM scenarios [31, 56, 57, 154–166]. The multi-component DM model has also some benefits over the single dark matter scenario. For instance, it can avoid some stringent constraints arising from various experiments that probe the properties and interactions of dark matter and other particles. A multi-component DM model can also accommodate different observational features of dark matter, such as its distribution and abundance in the universe.