QGG Intensive Lecture Series II

2nd Intensive Lectures by Quantum Gravity Gatherings

19-20 June 2023 @ RIKEN Wako, Japan

This is the second event by the Quantum Gravity Gatherings (QGG) Study Group at RIKEN iTHEMS. We invite Prof. Takahiro Tanaka from Kyoto University this time, and he will give pedagogical lectures on a large gauge transformation and its relation to the infrared (IR) divergence in the (quasi) de-Sitter spacetime. The IR structure is an important issue in all field-theoretical constructions, and we wish this event to provide insights to researchers in related fields.

This intensive lecture series is intended to be a lively and participatory event. The lectures are given in English, and the style is face-to-face using blackboards, without online streaming, to allow for active Q&A discussions in a casual atmosphere. In addition, there will be a session where any interested participant can give a short talk on any topic of his/her choice, which is intended to trigger interactions among all the participants, especially those in the early stages of their research career.



Intensive Lectures

Prof. Takahiro Tanaka (Kyoto University)

Large gauge transformation and infrared regularity in the inflationary universe

In this lecture we will start with the general framework to analyse the density perturbation in the inflationary universe. Then, we will introduce various infrared (IR) phenomena, including IR divergences, \(\delta N\) formalism and consistency relation. The underlying symmetry originally coming from 3D diffeomorphism invariance leads us to a harmonic and unified understanding of these phenomena. The lecture would consist of the following sections.

1) Quantum field in curved spacetime

2) General introduction to inflationary cosmology

3) Cosmological perturbation during inflation

4) Infrared Phenomena of Field Theory in the inflationary universe

5) Large gauge transformation and infrared regularity


June 19
10:00 - 10:15 Registration and reception (with coffee)
10:15 - 11:45 Lecture 1
11:45 - 13:30 Lunch & coffee break
13:30 - 15:00 Lecture 2
15:00 - 16:00 Coffee break
16:00 - 17:30 Lecture 3
17:45 - 18:30 Short talk session

June 20
10:00 - 10:15 Reception (with coffee)
10:15 - 11:45 Lecture 4
11:45 - 13:30 Lunch & coffee break
13:30 - 15:00 Lecture 5
15:00 - 16:00 Coffee break
16:00 - 17:30 Lecture 6
17:30 - 18:30 Discussions & Closing


535-537 Seminar Room, 5F of Main Research Building, RIKEN Wako Campus


Che-Yu Chen (iTHEMS)
Yuta Hamada (KEK)
Puttarak Jai-akson (iTHEMS)
Christy Kelly (iTHEMS)
Ryo Namba (iTHEMS)
Toshifumi Noumi (The University of Tokyo)
Naritaka Oshita (Kyoto Hakubi/iTHEMS)
Sotaro Sugishita (YITP)
Yuki Yokokura (iTHEMS)

Contact: Ryo Namba ryo.namba@riken.jp / Toshifumi Noumi tnoumi@g.ecc.u-tokyo.ac.jp