Particle physics models of inflation and curvaton scenarios (1001.0993v2)

Abstract: We review the particle theory origin of inflation and curvaton mechanisms for generating large scale structures and the observed temperature anisotropy in the cosmic microwave background (CMB) radiation. Since inflaton or curvaton energy density creates all matter, it is important to understand the process of reheating and preheating into the relevant degrees of freedom required for the success of Big Bang Nucleosynthesis. We discuss two distinct classes of models, one where inflaton and curvaton belong to the hidden sector, which are coupled to the Standard Model gauge sector very weakly. There is another class of models of inflaton and curvaton, which are embedded within Minimal Supersymmetric Standard Model (MSSM) gauge group and beyond, and whose origins lie within gauge invariant combinations of supersymmetric quarks and leptons. Their masses and couplings are all well motivated from low energy physics, therefore such models provide us with a unique opportunity that they can be verified/falsified by the CMB data and also by the future collider and non-collider based experiments. We then briefly discuss stringy origin of inflation, alternative cosmological scenarios, and bouncing universes.

• The paper presents a comparative analysis demonstrating how a scalar-driven inflation model coupled with the curvaton mechanism explains CMB anisotropies.
• It evaluates hidden sector and MSSM-based scenarios, emphasizing their testability and significance for cosmic structure formation.
• Insights into reheating and energy transfer processes offer predictive frameworks linking early universe dynamics with observable phenomena.

Overview of Particle Physics Models of Inflation and Curvaton Scenarios

The reviewed paper presents an in-depth exploration of inflationary and curvaton scenarios in the context of particle physics models, specifically focusing on their implications for cosmological phenomena such as the large-scale structure formation and cosmic microwave background (CMB) anisotropies. The authors, Anupam Mazumdar and Jonathan Rocher, systematically dissect these models while also considering the mechanisms of reheating and preheating, which are pivotal for the generation of all matter and subsequent processes like Big Bang Nucleosynthesis (BBN).

Inflation and Curvaton Mechanisms

The inflationary paradigm and curvaton scenario are two fundamental frameworks yielding predictions consistent with observed cosmological features. Inflation, primarily driven by a scalar inflaton field, is critical for addressing the horizon and flatness problems and is supported by CMB data. The curvaton mechanism, on the other hand, posits a secondary field which is responsible for generating curvature perturbations and complements the inflationary model in explaining CMB anisotropies.

Model Classifications

Two main categories of models are evaluated:

1. Hidden Sector Models: These models position the inflaton and curvaton in a hidden sector, with a limited coupling to the Standard Model (SM) gauge fields. These compositions are typically speculative, as the interactions with known particles are minimal, making experimental validation challenging.
2. MSSM-Based Models: This class involves placing inflaton and curvaton fields within the framework of the Minimal Supersymmetric Standard Model (MSSM) and potentially beyond. The particles in these models are gauge-invariant combinations of supersymmetric quarks and leptons, facilitating motivation from low-energy physics paradigms. A significant advantage of MSSM-based models is their potential testability through both CMB observations and high-energy physical experiments, given their relatively well-defined mass and coupling parameters.

Reheating and Preheating Processes

A critical aspect of these cosmological models is the behavior of the inflaton during and post-inflation, specifically its decay leading to reheating and thermalization of the universe. The reheating phase transitions the universe from inflationary vacuum energy domination to a radiation-dominated phase, crucial for initiating BBN. The efficiency and mechanisms of energy transfer during reheating remain pivotal topics of investigation to connect theoretical models with empirical cosmological data.

Advances and Prospective Directions

The paper briefly touches upon string theory based models of inflation as a potential avenue for future research, as well as exploring alternative cosmological scenarios, such as the hypothesis of bouncing universes as alternatives or complements to standard inflationary theory. These directions suggest promising areas for advancement, which may incorporate insights from high-energy physics or novel mathematical frameworks to further elucidate early universe dynamics.

Implications and Conclusion

The implications of this research extend significantly into realms of high-energy physics, cosmology, and potentially practical experimental physics. Models intricately involving MSSM extensions could feasibly become testable with future advancements in particle collider technologies or more precise cosmological measurements made by satellites detecting CMB anisotropies. The integration of theoretical constructs from SUGRA and string theory into inflationary models may likewise offer profound insights into both the fundamental particle framework and the macroscopic cosmos. The studies proposed in the paper hold the potential to enhance our understanding of the interface between particle physics and cosmology and could assist with the validation or refutation of these models through emerging empirical modalities.