→
Europe/Rome

Aula Bianchi (Scuola Normale Superiore)
### Aula Bianchi

#### Scuola Normale Superiore

Piazza dei Cavalieri, 7 Pisa

Description

11:00 - **Glenn Barnich **(ULB, Brussels)

Title:*Finite BMS transformations*

Abstract: After a review of holographic features of general relativity in 3 and 4 dimensions, I will show how to derive the transformation laws of the Bondi mass and angular momentum aspects under finite supertranslations, superrotations and complex Weyl rescalings.

12:00 Lunch break

14:30 -**Paul Townsend **(DAMPT, Cambridge)

Title:*Worldline time-reversal and a CPT anomaly*

Abstract: The action for a massless particle in 4D Minkowski spacetime has a worldline time-reversing symmetry corresponding to CPT invariance of the quantum theory. The analogous symmetry of the N-extended superparticle is anomalous when N is odd; in the supertwistor formalism this is seen as a 1D analog of the 3D Parity anomaly. This result accords with the fact that there are no CPT self-conjugate massless N=1 supermultiplet. There is one when N is even, and it has 2**N states when N/2 is even but 2**(N+1) when N/2 is odd. From the perspective of worldline time-reversal invariance, this state doubling for odd N/2 is due to a Kramers degeneracy.

15:30 Coffee break

16:00 -**Massimo Porrati **(NYU, New York))

Title:*Shaving off Black Hole Soft Hair*

Abstract: After recalling the definition of black hole "hair" we explain why the only interesting hair are those that are also remnants. Next, we will examine a recent proposal by Hawking, Perry and Strominger, who suggest that soft photons and gravitons can be regarded as black hole hair that may be relevant to the black hole information paradox. We will make use of factorization theorems for infrared divergences of the S-matrix to argue that, by appropriately dressing in and out hard states, the soft-quanta-dependent part of the S-matrix becomes essentially trivial, in the sense that the information paradox can be fully formulated in terms of dressed hard states, which do not depend on soft quanta.

Title:

Abstract: After a review of holographic features of general relativity in 3 and 4 dimensions, I will show how to derive the transformation laws of the Bondi mass and angular momentum aspects under finite supertranslations, superrotations and complex Weyl rescalings.

12:00 Lunch break

14:30 -

Title:

Abstract: The action for a massless particle in 4D Minkowski spacetime has a worldline time-reversing symmetry corresponding to CPT invariance of the quantum theory. The analogous symmetry of the N-extended superparticle is anomalous when N is odd; in the supertwistor formalism this is seen as a 1D analog of the 3D Parity anomaly. This result accords with the fact that there are no CPT self-conjugate massless N=1 supermultiplet. There is one when N is even, and it has 2**N states when N/2 is even but 2**(N+1) when N/2 is odd. From the perspective of worldline time-reversal invariance, this state doubling for odd N/2 is due to a Kramers degeneracy.

15:30 Coffee break

16:00 -

Title:

Abstract: After recalling the definition of black hole "hair" we explain why the only interesting hair are those that are also remnants. Next, we will examine a recent proposal by Hawking, Perry and Strominger, who suggest that soft photons and gravitons can be regarded as black hole hair that may be relevant to the black hole information paradox. We will make use of factorization theorems for infrared divergences of the S-matrix to argue that, by appropriately dressing in and out hard states, the soft-quanta-dependent part of the S-matrix becomes essentially trivial, in the sense that the information paradox can be fully formulated in terms of dressed hard states, which do not depend on soft quanta.

The agenda of this meeting is empty