A Phenomenological Study: Discussing the Relevant Theoretical and Experimental Constraints

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

4.3 Theoretical and experimental constraints

We discuss the relevant theoretical and experimental constraints in this section.

4.3.1 Vacuum Stability condition

The scalar potential 𝑉(𝐻, Φ, 𝜒) must be bounded from below [195] and it can be determined from the following symmetric matrix which comes from the quadratic part of the potential,

Above matrix will be positive-definite if following conditions are satisfied,

4.3.2 Invisible Higgs width constraint

In our model, ℎ1 scalar is SM Higgs by choice, which is the mixed state of three real scalar fields from eq. 4.6.

4.3.3 Relic density constraint

The relic density bound is from Planck satellite data [49].

Any DM candidate must satisfy the relic bound given in equation 4.42.