Infrared (IR) physics of quantum fluctuations in inflationary spacetimes has a rich structure. It has been suggested that several issues which have been separately discussed such as the soft theorem, the property of the IR radiative corrections, and so on, may have a tight connection.
Recently, there have been important progresses in understanding IR structures of gauge theories in asymptotically spacetimes. These progresses may bring us a new perspective on long-debated issues about IR physics in inflationary spacetimes.
IR fluctuations are supposed to undergo decoherence during inflation and stochastic approach is known to be a useful method to describe the decoherence process. It was suggested that understanding the influence of decoherence is also an important piece in uncovering the properties of IR fluctuations. Meanwhile, stochastic approach gives an effective field theory which also captures non-local influences of integrated-out hard modes.
In this workshop, after introductory lectures, we plan to discuss open questions about IR structures of gauge theories, bringing together experts who have worked on this issue from different perspectives. We hope this workshop provides a good occasion to contemplate these fundamental issues in a relaxing and calm environment.