# FY2022 Annual Report

**Quantum Gravity Unit
Assistant Professor Yasha Neiman**

## Abstract

This year, we worked on various projects. Yasha and Slava Lysov worked on a reformulation of higher-spin gravity using its BPS solution. Yasha also worked on the quartic locality of higher-spin gravity, and on self-dual General Relativity in de Sitter space, while Slava worked on the tropical-geometry version of mirror symmetry. Mirian Tsulaia and Dorin Weissman worked on higher-spin interaction vertices. Mirian also worked on supersymmetric quantum mechanics, while Dorin worked on holographic computations of QCD scattering amplitudes. Aritra Banerjee worked on fundamental and condensed-matter applications of Carrollian symmetry. Sebastian Murk worked on consistency conditions for astrophysical black-hole-like compact objects. Ardak Kussainova worked on solid-state physics. David O’Connell (Ph.D. student) worked on the topology and geometry of non-Hausdorff manifolds. Julian Lang (Ph.D. student) worked on the twistor space picture of type-B higher-spin holography.

## 1. Staff

- Dr. Mirian Tsulaia, Staff Scientist
- Dr. Vyacheslav Lysov, Postdoctoral Scholar
- Dr. Dorin Weissman, Postdoctoral Scholar
- Dr. Aritra Banerjee, Postdoctoral Scholar
- Dr. Sebastian Murk, Postdoctoral Scholar
- Dr. Ardak Kussainova, Postdoctoral Scholar
- David O'Connell, Graduate Student
- Julian Lang, Graduate Student
- Lena Hashimoto, Research Unit Administrator

## 2. Collaborations

### 2.1 **Supersymmetric cubic interactions from higher-spin approach**

- Description: Continued collaboration from previous FY
- Type of collaboration: Joint research
- Researchers:
- Dr. Mirian Tsulaia (OIST)
- Dr. Dorin Weissman (OIST)
- Prof. Joseph Buchbinder (Tomsk Pedagogical Institute and Tomsk State University)
- Prof. Vladimir Krykhtin (Tomsk Pedagogical Institute)

### 2.2 **Supersymmetric approach to discrete-time Schrodinger equation**

- Description: Inter-unit collaboration within OIST (continued from last FY)
- Type of collaboration: Joint research
- Researchers:
- Dr. Mirian Tsulaia (OIST Quantum Gravity Unit)
- Dr. Jonas Sonnenchein (OIST Theory of Quantum Matter Unit)

### 2.3 Mirror symmetry from tropical geometry

- Description: Continued collaboration from previous FY
- Type of collaboration: Joint research
- Researchers:
- Dr. Vyacheslav Lysov (OIST)
- Prof. Andrei Losev (National Research University Higher School of Economics, Moscow)

### 2.4 **Holographic description of hadron scattering **

- Description: Continued collaboration from previous FY
- Type of collaboration: Joint research
- Researchers:
- Dr. Dorin Weissman (OIST)
- Prof. Jacob Sonnenschein (Tel Aviv University)
- Prof. Massimo Bianchi (Rome University Tor Vergata)
- Dr. Maurizio Ferrotta (Rome University Tor Vergata)

### 2.5 **String and field theory in the Carrollian limit **

- Description: Continued & expanded collaboration from previous FY
- Type of collaboration: Joint research
- Researchers:
- Dr. Aritra Banerjee (OIST)
- Prof. Shankhadeep Chakrabortty (IIT Ropar)
- Prof. Arpan Bhattacharyya (IIT Gandhinagar)
- Prof. Arjun Bagchi (IIT Kanpur)
- Dr. Kedar S. Kolekar (IIT Kanpur)
- Sudipta Dutta (IIT Kanpur)
- Punit Sharma (IIT Kanpur)
- Ritankar Chatterjee (IIT Kanpur)
- Saikat Mondal (IIT Kanpur)
- Dr. Hisayoshi Muraki (POSTECH, Pohang)
- Dr. Aditya Mehra (BITS Pilani and University of Edinburgh)

### 2.6 **Carrollian symmetry in a Graphene system**

- Type of collaboration: Joint research
- Researchers:
- Dr. Aritra Banerjee (OIST)
- Prof. Rudranil Basu (BITS Pilani)
- Prof. Arjun Bagchi (IIT Kanpur)
- Saikat Mondal (IIT Kanpur)
- Minhajul Islam (IIT Kanpur)

### 2.7 **Bootstrap method for quantum mechanics with periodic potential**

- Type of collaboration: Joint research
- Researchers:
- Dr. Aritra Banerjee (OIST)
- Matthew Blacker (Cambridge University and OIST)
- Prof. Arpan Bhattacharyya (IIT Gandhinagar)

**2.8 Consistency conditions for alternative black hole models**

- Type of collaboration: Joint research
- Researchers:
- Dr. Sebastian Murk (OIST)
- Prof. Robert Mann (University of Waterloo)
- Prof. Daniel Terno (Macquarie University)
- Ioannis Soranidis (Macquarie University)

## 3. Activities and Findings

### 3.1 **New formulation of higher-spin gravity**

Yasha Neiman and Slava Lysov have developed a new formulation of higher-spin gravity. The formulation uses novel diagrammatic rules that interpolate between those of field and string theory. The main new ingredient is the Didenko-Vasiliev “BPS black hole”, which we understood to be the holographic dual of a bilocal operator in the boundary theory. The formulation uses only cubic vertices, some of which are still unknown, but have been proved to be local. The infinite tower of unknown and potentially non-local vertices at quartic and higher orders is completely avoided.

**3.2 Quartic locality of higher-spin gravity**

Yasha Neiman has re-examined the argument that the higher-spin gravity (in the standard, field-theoretic formulation) must be non-local at the quartic order. I found that the argument is valid for Lorentzian Anti-de Sitter space, but can be falsified by direct computation in Euclidean Anti-de Sitter or Lorentzian de Sitter space. Thus, higher-spin gravity provides a first example of a theory whose non-locality depends on the spacetime signature and the sign of the cosmological constant. Moreover, while my interest in this theory was motivated by its *compatibility* with de Sitter space, we now see that it *prefers* de Sitter space from the locality point of view.

**3.3 Self-dual gravity in de Sitter space**

Yasha Neiman has applied the novel Krasnov formulation of General Relativity to the problem of (non-linear) self-dual perturbations over de Sitter space. I found a lightcone ansatz for the solutions in Poincare coordinates, and showed how they can be applied to compute scattering in an observer’s static patch. Since the geometry is fluctuating, the static-patch scattering problem must be posed with great care. I showed how this can be done for the self-dual sector.

**3.4 Topology and geometry of non-Hausdorff manifolds**

David O’Connell continued developing the geometry of non-Hausdorff manifolds, with the aim of describing spacetimes with splitting and re-joining causal structures. In a preliminary result, he managed to demonstrate the Gauss-Bonnet theorem, which plays a key role in 2-dimensional gravity theories, in the perturbative expansion of string theory, and in black hole thermodynamics.

**3.5 Holographic QCD scattering computations**

Dorin Weissman and collaborators have pursued the study of scattering amplitudes in AdS/CFT, in which the boundary theory is a model of Quantum Chromodynamics, while the bulk is described by scattering strings. In particular, they characterized the signatures of chaos in these processes.

**3.6 Application of Carrollian symmetry to a Graphene system**

Aritra Banerjee and collaborators have continued their study of field theories with Carrollian symmetry and their applications. While the initial motivation for this work was the BMS symmetry of scattering amplitudes, they recently discovered a surprising and completely different arena for Carrollian dynamics, in a 2-layer Graphene system. The Carrollian symmetry predicts a special electronic band structure for this novel material.

**3.7 Modern methods for old-fashioned Quantum Mechanical problems**

Two recent projects involved the application of a technique from modern fundamental theory to problems in ordinary Quantum Mechanics. One was by Mirian Tsulaia and Jonas Sonnenschein (Shannon Unit at OIST), who applied supersymmetry to solve the time-discretized Schordinger equation for a variety of potentials. Another was by Aritra Banerjee and Matthew Blacker (intern), who applied the bootstrap technique from Confromal Field Theory to solve the Schrodinger equation with a periodic potential.

## 4. Publications

### 4.1 Journals

- Bagchi, A.,
**Banerjee, A.**, Basu, R., Islam, M., Mondal, S. “Magic fermions: Carroll and flat bands”.*Journal of High Energy Physics*, doi:10.1007/JHEP03(2023)227 (2023). **Tsulaia, M.**,**Weissman, D.**“Supersymmetric chiral quantum higher spin gravity”.*Journal of High Energy Physics*, doi:10.1007/JHEP12(2022)002 (2022).**Blacker, MJ.**, Bhattacharyya, A.,**Banerjee, A.**“Bootstrapping the Kronig-Penney model”.*Physical Review D*, doi:10.1103/PhysRevD.106.085005 (2022).**Lysov, V.**,**Neiman, Y.**“Bulk locality and gauge invariance for boundary-bilocal cubic correlators in higher-spin gravity”.*Journal of High Energy Physics*, doi:10.1007/JHEP12(2022)142 (2022).**Neiman, Y.**“Five questions about higher-spin holography in de Sitter space”.*Proceedings of Science*, doi:10.22323/1.406.0355 (2022).- Bianchi, M., Firrotta, M., Sonnenschein, J.,
**Weissman, D.**“Measure for chaotic scattering amplitudes”.*Physical Review Letters*, doi:10.1103/PhysRevLett.129.261601 (2022). **Lysov, V.**,**Neiman, Y.**“Higher-spin gravity’s ‘string’: new gauge and proof of holographic duality for the linearized Didenko-Vasiliev solution”.*Journal of High Energy Physics*, doi:10.1007/JHEP10(2022)054 (2022).**Banerjee, A.**, Mehra, A. “Maximally symmetric nonlinear extension of electrodynamics with Galilean conformal symmetries”.*Physical Review D*, doi:10.1103/PhysRevD.106.085005 (2022).**Banerjee, A.**, Bhattacharyya, A., Drashni, P., Pawar, S. “From CFTs to theories with Bondi-Metzner-Sachs symmetries: Complexity and out-of-time-ordered correlators”.*Physical Review D*, doi:10.1103/PhysRevD.106.126022 (2022).**Tsulaia, M.**, Sonnenschein, J. “A note on shape invariant potentials for discretized Hamiltonians”.*Modern Physics Letters A*, doi:10.1142/S021773232250153X (2022).- Bagchi, A.,
**Banerjee, A.**, Muraki, H. “Boosting to BMS”.*Journal of High Energy Physics*, doi:10.1007/JHEP09(2022)251 (2022). - Bagchi, A.,
**Banerjee, A.**, Dutta, S., Kolekar, KS., Sharma, P. “Carroll covariant scalar fields in two dimensions”.*Journal of High Energy Physics*, doi:10.1007/JHEP01(2023)072 (2023). - Buchbinder, IL., Krykhtin, VA.,
**Tsulaia, M.**,**Weissman, D.**“Supersymmetric cubic interactions for lower spins from ‘higher spin’ approach”.*Proceedings of Science*, doi:10.22323/1.412.0035 (2022). - Bianchi, M., Firrotta, M., Sonnenschein, J.,
**Weissman, D.**“Partonic behavior of string scattering amplitudes from holographic QCD models”.*Journal of High Energy Physics*, doi:10.1007/JHEP05(2022)058 (2022). - Bagchi, A.,
**Banerjee, A.**, Chakrabortty, S., Chatterjee, R. “A Rindler road to Carrollian worldsheets”.*Journal of High Energy Physics*, doi:10.1007/JHEP04(2022)082 (2022). **O’Connell, D.**, “Non-Hausdorff manifolds via adjunction spaces”.*Topology and its Applications*, doi:10.1016/j.topol.2022.108388 (2023).

### 4.2 Books and other one-time publications

- Murk, S. “Constraining modified gravity theories with physical black holes”.
*The 16*, doi:10.1142/9789811269776_0109 (2023).^{th}Marcel Grossmann meeting

### 4.3 Oral and Poster Presentations

- Bagchi, A.,
**Banerjee, A.**, Basu, R., Islam, M., Mondal, S. “Magic fermions: Carroll and flat bands”.*Carroll fermions, flat bands, Graphene and all that*, seminar at National Sun-Yat-Sen University, Sizihwan, Taiwan, Mar 24 (2023). - Losev, A.,
**Lysov, V.**“Tropical mirror symmetry: correlation functions”.*Tropical geometry and mirror symmetry*, OIST workshop “Women at the intersection of mathematics and theoretical physics meet in Okinawa”, Onna-son, Japan, Mar 20-24 (2023). - Bagchi, A.,
**Banerjee, A.**, Basu, R., Islam, M., Mondal, S. “Magic fermions: Carroll and flat bands”.*Carroll fermions, flat bands, Graphene and all that*, seminar at Kyoto University, Kyoto, Japan, Mar 7 (2023). **Neiman, Y.**“Self-dual gravity in de Sitter space: lightcone ansatz and static-patch scattering”.*Perturbation theory for self-dual gravity in de Sitter space*, seminar at Nottingham University, Nottingham, UK, Feb 24 (2023).**Neiman, Y.**“Quartic locality of higher-spin gravity in de Sitter and Euclidean Anti-de Sitter space”.*Locality of higher-spin gravity in de Sitter vs. Anti-de Sitter space*, seminar at King’s College London, London, UK, Feb 20 (2023).- Losev, A.,
**Lysov, V.**“Tropical mirror symmetry: correlation functions”.*Tropical mirror symmetry*, RIKKYO MathPhys 2023 conference, Tokyo, Japan, Jan 7-8 (2023). - Mann, R.,
**Murk, S.**, Terno, DR. “Black holes and their horizons in semiclassical and modified theories of gravity”.*Physical black holes in modified theories of gravity*, 24^{th}Australian Institute of Physics Congress, Adelaide, Australia, Dec 11-16 (2022). - Mann, R.,
**Murk, S.**, Terno, DR. “Surface gravity and the information loss problem”.*Surface gravity and information loss*, 24^{th}Australian Institute of Physics Congress, Adelaide, Australia, Dec 11-16 (2022). **Neiman, Y.**“New diagrammatic framework for higher-spin gravity”.*On the quartic locality problem in higher-spin gravity*, Joint Canada-Asia Pacific Conference on General Relativity and Relativistic Astrophysics, Pohang, Korea, Nov 28-Dec 2 (2023).**Neiman, Y.**“New diagrammatic framework for higher-spin gravity”.*A workaround and a direct objection to the quartic non-locality result*, APCTP workshop “Higher Spin Gravity and its Applications”, Pohang, Korea, Oct 12-17 (2023).**Neiman, Y.**“New diagrammatic framework for higher-spin gravity”.*Local reformulation of higher-spin gravity*, seminar at Weizmann Institute, Rehovot, Israel, Sep 19 (2022).- Bagchi, A.,
**Banerjee, A.**, Muraki, H. “Boosting to BMS”.*The curious case of Carrollian theories*, seminar at BITS Pilani, Pilani, India, Sep 17 (2022). - Buchbinder, IL., Krykhtin, VA.,
**Tsulaia, M.**, Weissman, D. “Cubic vertices for N=1 supersymmetric massless higher spin fields in various dimensions”.*Strings, supersymmetry and higher spins: foundations and modern developments*, Open Physics Seminar Series at V.N. Karazin Kharkiv National University, Kharkiv, Ukraine, Aug 15 (2022). - Bagchi, A.,
**Banerjee, A.**, Muraki, H. “Boosting to BMS”.*The curious case of Carrollian theories*, seminar at Le Center de Physique Theorique, Paris, France, Aug 3 (2022). - Skvortsov, E., Tran, T.,
**Tsulaia, M.**“A stringy theory in three dimensions and massive higher spins”.*Models with interacting massless and massive higher spin fields*, seminar at Yukawa Institute for Theoretical Physics, Kyoto, Japan, Jun 9 (2022). - Bagchi, A.,
**Banerjee, A.**, Dutta, S., Kolekar, KS., Sharma, P. “Carroll covariant scalar fields in two dimensions”.*The curious case of Carrollian theories*, seminars at IIT Kharagpur, Kharagpur, India, Apr 23-25 (2022).

## 5. Intellectual Property Rights and Other Specific Achievements

Nothing to report

## 6. Meetings and Events

**6.1 BMS field theories with U(1) symmetry**

- Date: February 15, 2023
- Venue: OIST Campus Lab4
- Speaker: Dr. Max Riegler (University of Vienna)

**6.2 Probing quantum gravity and non-locality through R^2-like inflation**

- Date: May 11, 2022
- Venue: OIST Campus Lab4
- Speaker: Dr. Sravan Kumar (Tokyo Institute of Technology)

- Date: June 17, 2010
- Venue: OIST Campus Lab1
- Co-organizers: The Institute of All But Cats (IABC)
- Speakers:
- Dr. First Last (Affiliation)
- Dr. First Last (Affiliation)
- Dr. First Last (Affiliation)

## 7. Other

Nothing to report.