Triangle Seminars
Monday, 5 Jun 2023
Gravitational Memory Effects: From Theory to Observation
Conference: 5 Jun 2023 - 9 Jun 2023
Description:
The past few years have witnessed a rapid growth of research in the low frequency sector of gravitational waves. This is triggered by various motivations: First, its observable consequences known as “memory effects” may be detected in the near future in current and planned gravitational wave detectors. Second, substantial breakthroughs in the holographic understanding of gravity in asymptotically flat spacetimes, have revealed a deep connection between memory and the underlying symmetries of quantum gravity. Third, novel methods to study gravitational scattering amplitudes have revealed detailed information about their soft limit. Accordingly, this topic lies at the interface between various fields of research, including quantum gravity, flat-space holography, gravitational wave theory, scattering amplitudes, mathematical GR and numerical relativity.
The goal of this meeting is to bring together experts from these different areas of research to discuss related topics and share their viewpoints. We hope that this meeting triggers new ideas and collaborations and make a bridge between different involved communities.
The past few years have witnessed a rapid growth of research in the low frequency sector of gravitational waves. This is triggered by various motivations: First, its observable consequences known as “memory effects” may be detected in the near future in current and planned gravitational wave detectors. Second, substantial breakthroughs in the holographic understanding of gravity in asymptotically flat spacetimes, have revealed a deep connection between memory and the underlying symmetries of quantum gravity. Third, novel methods to study gravitational scattering amplitudes have revealed detailed information about their soft limit. Accordingly, this topic lies at the interface between various fields of research, including quantum gravity, flat-space holography, gravitational wave theory, scattering amplitudes, mathematical GR and numerical relativity.
The goal of this meeting is to bring together experts from these different areas of research to discuss related topics and share their viewpoints. We hope that this meeting triggers new ideas and collaborations and make a bridge between different involved communities.
Posted by: a.seraj@qmul.ac.uk
Tuesday, 6 Jun 2023
TBA
Jorge Santos
(Cambridge University, DAMTP)
Abstract:
TBA
TBA
Posted by: IC
Blackhole, Blackring transition
📍 London
Indranil Halder
(Harvard)
Abstract:
We will discuss BPS objects in M theory compactified on a Calabi-Yau three fold X. From the microscopic point of view such degeneracies are encoded in the partition function of the topological strings on X through the Gopakumar-Vafa formula. For the first part of the talk, as an example we will focus on quintic, and discuss how Gopakumar-Vafa invariants can be calculated systematically from the knowledge of boundary condition on the moduli space together with holomorphic ambiguity equation and mirror symmetry. When the entropy thus obtained is plotted against the left moving angular momentum for fixed M2 brane charge, there is a clear transition point at a critical angular momentum. Comparison of the the curve with leading order results from supergravity in 5d shows a large deviation. We will explain the conceptual origin of such deviations using Ooguri-Strominger-Vafa conjecture in 4d string theory though 4d-5d lift. In particular we will observe that the curve is well approximated by the (suitably corrected) entropy of BMPV blackhole for smaller angular momentum and for larger angular momentum by the (suitably corrected) entropy of a particular EEMR blackring. We will show that these observations remain valid on a class of one parameter Calabi-Yau three folds.
We will discuss BPS objects in M theory compactified on a Calabi-Yau three fold X. From the microscopic point of view such degeneracies are encoded in the partition function of the topological strings on X through the Gopakumar-Vafa formula. For the first part of the talk, as an example we will focus on quintic, and discuss how Gopakumar-Vafa invariants can be calculated systematically from the knowledge of boundary condition on the moduli space together with holomorphic ambiguity equation and mirror symmetry. When the entropy thus obtained is plotted against the left moving angular momentum for fixed M2 brane charge, there is a clear transition point at a critical angular momentum. Comparison of the the curve with leading order results from supergravity in 5d shows a large deviation. We will explain the conceptual origin of such deviations using Ooguri-Strominger-Vafa conjecture in 4d string theory though 4d-5d lift. In particular we will observe that the curve is well approximated by the (suitably corrected) entropy of BMPV blackhole for smaller angular momentum and for larger angular momentum by the (suitably corrected) entropy of a particular EEMR blackring. We will show that these observations remain valid on a class of one parameter Calabi-Yau three folds.
Posted by: andrea
Wednesday, 7 Jun 2023
Quantum and Classical Eikonal Scattering
📍 London
Giulia Isabella
(Geneva)
Abstract:
I will discuss the eikonal scattering of two gravitationally interacting bodies, showing that exponentiation of the scattering phase matrix is a direct consequence of the group contraction \(SU(2) \rightarrow ISO(2)\), in the large angular momentum limit. The emergence of the classical limit is understood in terms of the continuous-spin representations admitted by \(ISO(2)\). We will compare the competing classical and quantum corrections to the leading classical eikonal scattering in the transplanckian regime and discuss how observables are extracted from the scattering phase matrix.
I will discuss the eikonal scattering of two gravitationally interacting bodies, showing that exponentiation of the scattering phase matrix is a direct consequence of the group contraction \(SU(2) \rightarrow ISO(2)\), in the large angular momentum limit. The emergence of the classical limit is understood in terms of the continuous-spin representations admitted by \(ISO(2)\). We will compare the competing classical and quantum corrections to the leading classical eikonal scattering in the transplanckian regime and discuss how observables are extracted from the scattering phase matrix.
Posted by: andrea
Thursday, 8 Jun 2023
Information loss, black holes, and algebras in time
📍 London
Nima Lashkari
(Purdue)
Abstract:
A manifestation of the black hole information loss problem is that the two-point function of probe operators in an eternal AdS black hole decays exponentially fast in time, whereas, on the boundary, it is expected to be an almost periodic function of time. We point out that the decay of the two-point function (clustering in time) holds important clues to the nature of observable algebras, states, and dynamics in quantum gravity. In the thermodynamic limit of infinite entropy (infinite volume or large N), the operators that cluster in time are expected to form an algebra. We prove that this algebra is a unique and very special infinite dimensional algebra called the III_1 factor. This has implications for the emergence of a local bulk in holography.
An important example is \mathcal{N}=4 SYM, above the Hawking-Page phase transition. The clustering of the single trace operators implies that the algebra is a type III_1 factor. We prove a generalization of a conjecture of Leutheusser and Liu to arbitrary out-of-equilibrium states. We explicitly construct the C^*-algebra and von Neumann subalgebras associated with time bands and more generally, arbitrary open sets of the bulk spacetime in the strict N\to \infty limit. The emergence of time algebras is intimately tied to the second law of thermodynamics and the emergence of an arrow of time.
A manifestation of the black hole information loss problem is that the two-point function of probe operators in an eternal AdS black hole decays exponentially fast in time, whereas, on the boundary, it is expected to be an almost periodic function of time. We point out that the decay of the two-point function (clustering in time) holds important clues to the nature of observable algebras, states, and dynamics in quantum gravity. In the thermodynamic limit of infinite entropy (infinite volume or large N), the operators that cluster in time are expected to form an algebra. We prove that this algebra is a unique and very special infinite dimensional algebra called the III_1 factor. This has implications for the emergence of a local bulk in holography.
An important example is \mathcal{N}=4 SYM, above the Hawking-Page phase transition. The clustering of the single trace operators implies that the algebra is a type III_1 factor. We prove a generalization of a conjecture of Leutheusser and Liu to arbitrary out-of-equilibrium states. We explicitly construct the C^*-algebra and von Neumann subalgebras associated with time bands and more generally, arbitrary open sets of the bulk spacetime in the strict N\to \infty limit. The emergence of time algebras is intimately tied to the second law of thermodynamics and the emergence of an arrow of time.
Posted by: andrea