We study the dynamics of a cosmological bubble wall beyond the approximation
of an infinitely thin wall. In a previous paper, we discussed the range of
validity of this approximation and estimated the first-order corrections due to
the finite width. Here, we introduce a systematic method to obtain the wall
equation of motion and its profile at each order in the wall width. We discuss
in detail the next-to-next-to-leading-order terms. We use the results to treat
the growth of spherical bubbles and the evolution of small deformations of
planar walls.

Conclusion:

In this study, we have gone beyond the approximation of an infinitely thin wall in order to understand the dynamics of a cosmological bubble wall more accurately. We have discussed the range of validity of this approximation and estimated the corrections due to the finite width of the wall. Additionally, we have introduced a systematic method to obtain the equation of motion and profile of the wall at each order in the wall width, specifically focusing on the next-to-next-to-leading-order terms. These results have been applied to investigate the growth of spherical bubbles and the evolution of small deformations of planar walls.

Future Roadmap:

Building on the insights obtained from this study, there are several potential future directions to explore:

  • Refining the systematic method: While we have developed a systematic method to obtain the wall equation of motion and profile at each order in the wall width, there is room for further refinement. Investigating alternative approaches or utilizing advanced mathematical techniques may help improve the accuracy and efficiency of our calculations.
  • Higher-order corrections: In this study, we focused on the next-to-next-to-leading-order terms. However, there are still higher-order corrections that can be explored. Understanding these higher-order effects is crucial for obtaining a complete understanding of the dynamics of cosmological bubble walls.
  • Generalizations to other geometries: While we have examined the growth of spherical bubbles and small deformations of planar walls, extending our analysis to other geometries can provide a more comprehensive understanding of bubble wall dynamics. Investigating cylindrical or higher-dimensional walls may uncover new insights and challenges.
  • Experimental verification: Although our study has focused on theoretical calculations, experimental verification is essential for validating our findings. Collaborating with experimental physicists or proposing experimental setups to test the predictions derived from our theoretical framework would strengthen the reliability of our results.
  • Applications in cosmology: Understanding the dynamics of cosmological bubble walls is not only of fundamental interest but also has potential applications in cosmology. Investigating the consequences of bubble wall dynamics on various cosmological phenomena such as phase transitions, cosmic inflation, or dark matter could lead to significant advancements in our understanding of the universe.

While there are exciting opportunities for further research, several challenges may arise along the way:

  1. Computational complexity: As we delve deeper into higher-order corrections and explore more complex geometries, the computational complexity of our calculations may increase significantly. Developing efficient algorithms or utilizing computational resources effectively will be crucial to overcome this challenge.
  2. Limited experimental data: Experimental verification of our theoretical predictions may be limited by access to appropriate experimental setups or the feasibility of conducting certain experiments. Collaborative efforts with experimental physicists and innovative experimental designs will be necessary to overcome these limitations.
  3. Interdisciplinary collaborations: Advancing our understanding of cosmological bubble walls requires interdisciplinary collaborations between theoretical physicists, experimental physicists, and mathematicians. Effective communication and collaboration across different fields can be challenging but are essential for making progress.
  4. Limited funding and resources: Research in theoretical physics often requires significant funding for computational resources, research materials, and collaborations. Securing adequate funding and resources for future research endeavors may pose challenges and require active pursuit of grants and partnerships.

In summary, this study has laid the foundation for a more accurate understanding of cosmological bubble walls by going beyond the approximation of an infinitely thin wall. With further refinements and exploration of higher-order corrections, as well as investigations into different geometries, experimental verification, and applications in cosmology, we can expect significant advancements in our understanding of the dynamics and implications of bubble walls in the universe. Nonetheless, challenges related to computational complexity, limited experimental data, interdisciplinary collaborations, and funding must be acknowledged and actively addressed.

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