We classify a one-parameter family,   <math> <mtext>confcar</mtext> <msub> <mi>r</mi> <mi>z</mi> </msub> <mfenced> <mrow> <mi>d</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfenced> </math>  $$ \mathfrak{confcar}{\mathfrak{r}}_z\left(d+1\right) $$ , of conformal extensions of the Carroll algebra in arbitrary dimension with z being the anisotropic scaling exponent. We further obtain their infinite-dimensional extensions,   <math> <msub> <mover> <mtext>confcarr</mtext> <mo>~</mo> </mover> <mi>z</mi> </msub> <mfenced> <mrow> <mi>d</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfenced> </math>  $$ {\overset{\sim }{\mathfrak{confcarr}}}_z\left(d+1\right) $$ , and discuss their corresponding finite-dimensional truncated subalgebras when the scaling exponent is integer or half-integer. For all these conformal extensions, we also constrain the 2-point and 3-point correlation functions with electric and/or magnetic features.

Iran

Hamid Afshar

France

Xavier Bekaert

Mojtaba Najafizadeh

Classification of conformal carroll algebras

We study the asymptotic dynamics of 3D gravity with Rindler boundary conditions both in flat and AdS spacetimes. We do this by using the angular quantization and Hamiltonian reduction of the action to the Wess-Zumino-Witten theory on the boundary. We then rewrite the boundary action as a functional of elements of the asymptotic symmetry group.

Narges Aghamir

The near horizon dynamics in three-dimensional Einstein gravity

We study holographic aspects of 2D dilaton-supergravity in flat space-time using gauge theoretic BF formulation. The asymptotic symmetries in Bondi gauge and at finite temperature span a supersymmetric extension of the warped Virasoro algebra at level zero. The boundary action is determined such that the bulk variational principle is ensured and turns out to be a super-warped Schwarzian theory at the vanishing level. We also study the thermodynamics of the black hole saddle in this model.

Holography in   <math> <mover> <mtext>CGHS</mtext> <mo>̂</mo> </mover> </math>  $$ \hat{\textrm{CGHS}} $$  supergravity

We consider Minkowskian Jackiw-Teitelboim (JT) gravity in Bondi gauge at finite temperature, with non-zero vacuum energy. Its asymptotic symmetries span an extension of the warped Virasoro group, dubbed ‘BMS2’, which we investigate in detail. In particular, we show that this extension has a single coadjoint orbit when central charges are real and non-zero. The ensuing BMS-Schwarzian action has no saddle points, and only coincides with the boundary action functional of flat JT gravity up to a crucial dilatonic zero-mode that ensures the existence of a well-defined bulk variational principle. We evaluate the corresponding gravitational partition function, which turns out to be one-loop exact precisely thanks to the presence of such a zero-mode.

Blagoje Oblak

Flat JT gravity and the BMS-Schwarzian

We present an interacting spin-2 gauge theory coupled to the two-dimensional dilaton-gravity in flat spacetime. The asymptotic symmetry group is enhanced to the central extension of Diff(S 1)⋉C  ∞ (S 1)⋉Vec(S 1) when the central element of the Heisenberg subgroup is zero (vanishing U(1) level). Using the BF-formulation of the model we derive the corresponding boundary coadjoint action which is the spin-2 extension of the warped Schwarzian theory at vanishing U(1) level. We also discuss the thermodynamics of black holes in this model.

Erfan Esmaeili

H. Safari

Flat space holography in spin-2 extended dilaton-gravity

We provide the first steps toward a flat space holographic correspondence in two bulk spacetime dimensions. The gravity side is described by a conformally transformed version of the matterless Callan-Giddings-Harvey-Strominger model. The field theory side follows from the complex Sachdev-Ye-Kitaev model in the limit of large specific heat and vanishing compressibility. We derive the boundary action analogous to the Schwarzian as the key link between gravity and field theory sides and show that it coincides with a geometric action discovered recently by one of us [H. R. Afshar, Warped Schwarzian theory, J. High Energy Phys. 02 (2020) 126].

Austria

Chile

Hernán A. González

Daniel Grumiller

Brazil

Russia

Dmitri Vassilevich

Flat space holography and the complex Sachdev-Ye-Kitaev model

We consider the (twisted) warped Virasoro group Diff(S 1)⋉C ∞ (S 1) in the presence of its three cocycles. We compute the Kirillov-Kostant-Souriau symplectic 2-form on coadjoint orbits. We then construct the Euclidean action of the ‘warped Schwarzian theory’ associated to the orbit with SL(2,ℝ)×U(1) stabilizer as the effective theory of the reparametrization over the base circle and evaluate the corresponding one-loop-exact path integral. We further discuss thermodynamics of the wSch theory in comparison with the complex SYK model.

Warped Schwarzian theory

We introduce a systematic way of constructing 3D exotic massive gravity theories in the first order formulation. Our method is based on truncating a single degree of freedom in the parity odd gravity models found earlier [1] and supplementing it with appropriate potential terms such that the resulting models have well-defined metric equations but their Bianchi identities are satisfied only on-shell. Hence, they are ‘third way’ consistent. We first re-derive two already known exotic theories using our approach and then construct an extended exotic massive gravity model whose metric field equation is sixth order in derivatives. We also explain how to check Bianchi identities using the first order formulation.

Türkiye

Nihat Deger

Exotic massive 3D gravities from truncation

In systems with local gauge symmetries, the memory effect corresponds to traces inscribed on a suitable probe when a pure gauge configuration at infinite past dynamically evolves to another pure gauge configuration at infinite future. In this work, we study the memory effect of 2-form gauge fields which is probed by strings. We discuss the “string memory effect” for closed and open strings at classical and quantum levels. The closed string memory is encoded in the internal excited modes of the string, and in the open string case, it is encoded in the relative position of the two endpoints and the non-commutativity parameter associated with the D-brane where the open string endpoints are attached. We also discuss 2-form memory with D-brane probes using boundary state formulation and, the relation between string memory and 2-form soft charges analyzed in [1].

M. Sheikh-Jabbari

String memory effect

We derive the covariant Poisson’s equation of (d + 1)-dimensional Newton-Cartan gravity with (twistless) torsion by applying the ‘non-relativistic conformal method’ introduced in [1]. We apply this method on-shell to a Schrödinger field theory on the curved Newton-Hooke background. The covariance of the field equation in the presence of the non-relativistic cosmological constant, entails fixing all coefficients in the covariant Poisson’s equation for (twistless) torsional Newton-Cartan gravity. We further derive Ehlers conditions and an equation associated to the torsion in this method.