Inflation in Supergravity with a Single Chiral Superfield
The paper "Inflation in Supergravity with a Single Chiral Superfield" by Sergei V. Ketov and Takahiro Terada presents a novel approach to realize chaotic inflation within the framework of supergravity using a single chiral superfield. Traditionally, achieving inflationary models within supergravity requires a complex interplay of multiple fields or modifications to the basic setup to stabilize field dynamics and ensure desirable inflationary potentials. This paper addresses how one can construct inflationary models reminiscent of Linde and Starobinsky-type inflation using just one chiral superfield, thus enabling a simplified setting for inflationary model building in supergravity.
The authors suggest stabilizing the real or imaginary components of the inflaton by modifying the Kähler potential and employing polynomial superpotentials to achieve a positive vacuum energy during large-field inflation. The paper's central focus is on two inflationary models: one based on chaotic Linde-type inflation and the other linked to Starobinsky-like inflation.
Key Contributions and Results
- Chaotic Inflation Model:
- The paper outlines a method to achieve chaotic inflation reminiscent of Linde-type models by using higher dimensional operators in the Kähler potential for stabilization of the field components. For example, they propose modifying the standard Kähler potential to include stabilization terms that help in maintaining the positive definite nature of the inflaton scalar potential during inflation.
- By selecting appropriate parameters and the form of superpotentials, the authors show how a quadratic potential can be realized for the inflaton, which aligns with the standard Linde-type inflation model predictions for spectral index and tensor-to-scalar ratio.
- Starobinsky Inflation Model:
- The paper also addresses the development of Starobinsky-type inflation. In this model, achieving a scalar potential that asymptotically approaches a constant in the large field region is crucial.
- The authors propose two modifications to the superpotential to achieve the desired inflationary dynamics. These modifications ensure the scalar potential allows for Starobinsky-type planarity without requiring additional fields.
- The numerical results and evaluations showcase how these models can achieve observational compatibility with Cosmic Microwave Background data, indicating their potential as plausible scenarios for realistic inflation within supergravity.
Implications and Future Prospects
The method proposed in the paper offers a significant simplification to constructing inflationary models in supergravity, potentially making the models more straightforward to analyze and more easily integrated into broader cosmological frameworks. Such simplification and clarity could make these models advantageous for future theoretical and computational explorations. Furthermore, the flexibility demonstrated in achieving desired inflationary potentials using polynomial superpotentials hints at a deeper capability within supergravity models to encompass a wider range of inflationary scenarios.
The implications go beyond theoretical elegance. Achieving influential cosmological models within a truncated setup has ramifications for understanding the nature of supersymmetry and its connection to observable physics beyond the Standard Model. The alignment with current observational data from WMAP and Planck also ensures relevance and encourages further research, potentially extending beyond single-field models to more complex interactions and dynamics within supergravity.
Conclusion
This paper exhibits how inflationary dynamics can be simulated within the confines of supergravity using a minimalistic setup. By stabilizing components and employing polynomial terms, Ketov and Terada provide a foundational approach for single-field inflationary models in supergravity that can be used as benchmarks for future theoretical developments. The realization and investigation of these models contribute significantly to the understanding of early universe cosmology and its intersection with particle physics theories like supersymmetry. As future observational data become available, these models offer the potential for improving theoretical predictions and understanding the fundamental forces shaping our universe.