A Pseudo-Scalar Dark Matter Case: An Introduction to Get You Up to Speed

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

In this chapter, we study a pseudo-scalar DM in a generic U(1)𝑋 extension of SM. The results are based on the work: Shivam Gola, "Pseudo scalar dark matter in a generic U(1)𝑋 model, Phys.Lett.B 842 (2023) 137982”

4.1 Introduction

WIMP-type dark matter is heavily constrained by direct experimental searches [32, 184]; therefore, to continue with WIMP, one has to find a way to evade the stringent direct detection bounds.

A pseudo-scalar DM can naturally evade the strong direct detection constraints as it has derivative couplings that imply a momentum suppression in the tree-level DM-nucleon scattering matrix, which vanishes in the non-relativistic limit [185–192]. Hence, it is interesting to seek a pseudo-scalar particle as a WIMP dark matter.

In this chapter, we consider a generic U(1)𝑋 model for pseudo-scalar DM and discuss its phenomenological implications in this study. The interesting aspect of the 𝑈(1)𝑋 models is that the three generations of right-handed neutrinos (RHNs) are required to eliminate the gauge and mixed gauge-gravity anomalies [144–147]. The RHNs mix with active neutrinos of SM via type I seesaw mechanism [71–74] to generate the required light neutrino masses and flavor mixing. A model that explains both the neutrino mass problem and the nature of dark matter would be a major step forward in high-energy physics [148–153].

The pseudo-scalar is not protected by any symmetry; therefore, for it to be a DM candidate, it must have a lifetime much greater than the age of the universe. We study the feasible parameter space allowed by the lifetime constraint on our pseudo-scalar particle, then we scan for the allowed parameter space by relic and direct detection bounds while respecting several other theoretical and experimental constraints.

The chapter is organised as follows: In sec. 4.2, we introduce the model and discuss the details of the new fields and their interactions. In sec. 4.3, we discuss some of the relevant theoretical and experimental constraints. In sec. 4.4, we discuss relic density, direct detection, and other phenomenologically relevant studies. Finally, in sec. 4.5, we summarize the chapter.