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Welcome to Celestial Holography

Lecturer
Agata Grechko (IFUSP, Brazil)
Language
English
Schedule
13–16 Jul 2026 (4 classes)
Time
11h00 (BRT)/14h00 (UTC)
Workload
8h
Topics
  • Lecture 1. Introduction: soft theorems, asymptotic flatness, and CFT
    • Weinberg's soft theorems and beyond
    • Asymptotically flat spacetimes, Bondi gauge and BMS transformations
    • Gravitational symmetries and infrared triangle
    • 2D CFT basics
  • Lecture 2. From momentum space to celestial sphere
    • Lorentz algebra and $\mathrm{sl}(2,\mathbb{C})$ algebra
    • Conformal primary wavefunctions
    • Celestial basis for scattering amplitudes with examples
  • Lecture 3. Symmesties on the celestial sphere
    • Ward identities and soft theorems
    • Subleading soft-factors and superrotations
    • Shadow transform
    • Celestial IR triangle
  • Lecture 4. Open questions and last frontiers
    • Celestial OPEs and colinear limit
    • $w_{1+\infty}$ algebra
    • Connections with string theory and twistors
Prerequisites
Quantum field theory and general relativity. Previous experience with conformal field theory is helpful, but not necessary.
Bibliography