scholarly journals Asymptotic symmetries and celestial CFT

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Laura Donnay ◽  
Sabrina Pasterski ◽  
Andrea Puhm
Keyword(s):  
Principal Series ◽  
Finite Energy ◽  
Continuous Series ◽  
Asymptotic Symmetry ◽  
Null Infinity ◽  
Conformal Dimension ◽  
Contour Integrals ◽  
Celestial Sphere ◽  
Goldstone Modes ◽  
Asymptotic Symmetries

Abstract We provide a unified treatment of conformally soft Goldstone modes which arise when spin-one or spin-two conformal primary wavefunctions become pure gauge for certain integer values of the conformal dimension ∆. This effort lands us at the crossroads of two ongoing debates about what the appropriate conformal basis for celestial CFT is and what the asymptotic symmetry group of Einstein gravity at null infinity should be. Finite energy wavefunctions are captured by the principal continuous series ∆ ∈ 1 + iℝ and form a complete basis. We show that conformal primaries with analytically continued conformal dimension can be understood as certain contour integrals on the principal series. This clarifies how conformally soft Goldstone modes fit in but do not augment this basis. Conformally soft gravitons of dimension two and zero which are related by a shadow transform are shown to generate superrotations and non-meromorphic diffeomorphisms of the celestial sphere which we refer to as shadow superrotations. This dovetails the Virasoro and Diff(S2) asymptotic symmetry proposals and puts on equal footing the discussion of their associated soft charges, which correspond to the stress tensor and its shadow in the two-dimensional celestial CFT.

scholarly journals Massive celestial fermions

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Sruthi A. Narayanan
Keyword(s):  
Principal Series ◽  
Delta Function ◽  
Inner Product ◽  
Dirac Fermions ◽  
Conformal Dimension ◽  
Single Spin ◽  
Massive Spin ◽  
Poincaré Algebra ◽  
Dimension 2 ◽  
Celestial Sphere

Abstract In an effort to further the study of amplitudes in the celestial CFT (CCFT), we construct conformal primary wavefunctions for massive fermions. Upon explicitly calculating the wavefunctions for Dirac fermions, we deduce the corresponding transformation of momentum space amplitudes to celestial amplitudes. The shadow wavefunctions are shown to have opposite spin and conformal dimension 2 − ∆. The Dirac conformal primary wave- functions are delta function normalizable with respect to the Dirac inner product provided they lie on the principal series with conformal dimension ∆ = 1 + iλ for λ ∈ ℝ. It is shown that there are two choices of a complete basis: single spin $$ J=\frac{1}{2} $$ J = 1 2 or $$ J=-\frac{1}{2} $$ J = − 1 2 and λ ∈ ℝ or multiple spin $$ J=\pm \frac{1}{2} $$ J = ± 1 2 and λ ∈ ℝ+∪0. The massless limit of the Dirac conformal primary wavefunctions is shown to agree with previous literature. The momentum generators on the celestial sphere are derived and, along with the Lorentz generators, form a representation of the Poincaré algebra. Finally, we show that the massive spin-1 conformal primary wavefunctions can be constructed from the Dirac conformal primary wavefunctions using the standard Clebsch-Gordan coefficients. We use this procedure to write the massive spin-$$ \frac{3}{2} $$ 3 2 , Rarita-Schwinger, conformal primary wavefunctions. This provides a prescription for constructing all massive fermionic and bosonic conformal primary wavefunctions starting from spin-$$ \frac{1}{2} $$ 1 2 .

scholarly journals Conformally soft fermions

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Yorgo Pano ◽  
Sabrina Pasterski ◽  
Andrea Puhm
Keyword(s):  
Gauge Theory ◽  
Inner Product ◽  
Conformal Dimension ◽  
Infinite Dimensional ◽  
Primary Operator ◽  
Left And Right ◽  
Symmetry Generators ◽  
Goldstone Modes ◽  
Asymptotic Symmetries

Abstract Celestial diamonds encode the global conformal multiplets of the conformally soft sector, elucidating the role of soft theorems, symmetry generators and Goldstone modes. Upon adding supersymmetry they stack into a pyramid. Here we treat the soft charges associated to the fermionic layers that tie this structure together. This extends the analysis of conformally soft currents for photons and gravitons which have been shown to generate asymptotic symmetries in gauge theory and gravity to infinite-dimensional fermionic symmetries. We construct fermionic charge operators in 2D celestial CFT from a suitable inner product between 4D bulk field operators and spin s = $$ \frac{1}{2} $$ 1 2 and $$ \frac{3}{2} $$ 3 2 conformal primary wavefunctions with definite SL(2, ℂ) conformal dimension ∆ and spin J where |J| ≤ s. The generator for large supersymmetry transformations is identified as the conformally soft gravitino primary operator with ∆ = $$ \frac{1}{2} $$ 1 2 and its shadow with ∆ = $$ \frac{3}{2} $$ 3 2 which form the left and right corners of the celestial gravitino diamond. We continue this analysis to the subleading soft gravitino and soft photino which are captured by degenerate celestial diamonds. Despite the absence of a gauge symmetry in these cases, they give rise to conformally soft factorization theorems in celestial amplitudes and complete the celestial pyramid.

scholarly journals Asymptotic symmetries and charges at null infinity: from low to high spins

2018 ◽  
Vol 191 ◽  
pp. 06011 ◽  
Author(s):  
Andrea Campoleoni ◽  
Dario Francia ◽  
Carlo Heissenberg
Keyword(s):  
Symmetry Group ◽  
A Priori ◽  
Asymptotic Symmetry ◽  
Null Infinity ◽  
Infinite Dimensional ◽  
S Matrix ◽  
Higher Spin ◽  
Matrix Invariant ◽  
Higher Spins ◽  
Asymptotic Symmetries

Weinberg’s celebrated factorisation theorem holds for soft quanta of arbitrary integer spin. The same result, for spin one and two, has been rederived assuming that the infinite-dimensional asymptotic symmetry group of Maxwell’s equations and of asymptotically flat spaces leave the S-matrix invariant. For higher spins, on the other hand, no such infinite-dimensional asymptotic symmetries were known and, correspondingly, no a priori derivation of Weinberg’s theorem could be conjectured. In this contribution we review the identification of higher-spin supertranslations and superrotations in D = 4 as well as their connection to Weinberg’s result. While the procedure we follow can be shown to be consistent in any D, no infinite-dimensional enhancement of the asymptotic symmetry group emerges from it in D > 4, thus leaving a number of questions unanswered.

Kleinian characterization of asymptotic symmetries of real general relativity

1993 ◽  
Vol 441 (1913) ◽  
pp. 465-471 ◽  
Keyword(s):  
General Relativity ◽  
Automorphism Group ◽  
Group Action ◽  
Radon Transform ◽  
Symmetry Groups ◽  
Asymptotic Symmetry ◽  
The Real ◽  
The Given ◽  
Asymptotic Symmetries

According to Klein’s Erlanger programme, one may (indirectly) specify a geometry by giving a group action. Conversely, given a group action, one may ask for the corresponding geometry. Recently, I showed that the real asymptotic symmetry groups of general relativity (in any signature) have natural ‘projective’ classical actions on suitable ‘Radon transform’ spaces of affine 3-planes in flat 4-space. In this paper, I give concrete models for these groups and actions. Also, for the ‘atomic’ cases, I give geometric structures for the spaces of affine 3-planes for which the given actions are the automorphism group.

scholarly journals Celestial diamonds: conformal multiplets in celestial CFT

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Sabrina Pasterski ◽  
Andrea Puhm ◽  
Emilio Trevisani
Keyword(s):  
Gauge Theory ◽  
Scattering Amplitudes ◽  
Explicit Construction ◽  
Conformal Dimension ◽  
Massless Particles ◽  
Special Values ◽  
Left And Right ◽  
Opposite Helicity ◽  
Asymptotic Symmetries

Abstract We examine the structure of global conformal multiplets in 2D celestial CFT. For a 4D bulk theory containing massless particles of spin s = $$ \left\{0,\frac{1}{2},1,\frac{3}{2},2\right\} $$ 0 1 2 1 3 2 2 we classify and construct all SL(2,ℂ) primary descendants which are organized into ‘celestial diamonds’. This explicit construction is achieved using a wavefunction-based approach that allows us to map 4D scattering amplitudes to celestial CFT correlators of operators with SL(2,ℂ) conformal dimension ∆ and spin J. Radiative conformal primary wavefunctions have J = ±s and give rise to conformally soft theorems for special values of ∆ ∈ $$ \frac{1}{2}\mathbb{Z} $$ 1 2 ℤ . They are located either at the top of celestial diamonds, where they descend to trivial null primaries, or at the left and right corners, where they descend both to and from generalized conformal primary wavefunctions which have |J| ≤ s. Celestial diamonds naturally incorporate degeneracies of opposite helicity particles via the 2D shadow transform relating radiative primaries and account for the global and asymptotic symmetries in gauge theory and gravity.

scholarly journals Asymptotic symmetry and asymptotic solutions to Ito stochastic differential equations

2022 ◽  
Vol 4 (5) ◽  
pp. 1-52
Author(s):  
Giuseppe Gaeta ◽  
◽  
Roma Kozlov ◽  
Francesco Spadaro ◽  
◽  
...  
Keyword(s):  
Differential Equations ◽  
Stochastic Differential Equations ◽  
Asymptotic Solutions ◽  
Asymptotic Symmetry ◽  
Asymptotic Approach ◽  
Stochastic Setting ◽  
Asymptotic Symmetries

<abstract><p>We consider several aspects of conjugating symmetry methods, including the method of invariants, with an asymptotic approach. In particular we consider how to extend to the stochastic setting several ideas which are well established in the deterministic one, such as conditional, partial and asymptotic symmetries. A number of explicit examples are presented.</p></abstract>

scholarly journals Lie theory for asymptotic symmetries in general relativity: The BMS Group

2022 ◽  
Author(s):  
David Nicolas Prinz ◽  
Alexander Schmeding
Keyword(s):  
General Relativity ◽  
Lie Group ◽  
Group Structure ◽  
Symmetry Groups ◽  
Asymptotic Symmetry ◽  
Infinite Dimensional ◽  
Real Analytic ◽  
Definition Of ◽  
Future Work ◽  
Asymptotic Symmetries

Abstract We study the Lie group structure of asymptotic symmetry groups in General Relativity from the viewpoint of infinite-dimensional geometry. To this end, we review the geometric definition of asymptotic simplicity and emptiness due to Penrose and the coordinate-wise definition of asymptotic flatness due to Bondi et al. Then we construct the Lie group structure of the Bondi--Metzner--Sachs (BMS) group and discuss its Lie theoretic properties. We find that the BMS group is regular in the sense of Milnor, but not real analytic. This motivates us to conjecture that it is not locally exponential. Finally, we verify the Trotter property as well as the commutator property. As an outlook, we comment on the situation of related asymptotic symmetry groups. In particular, the much more involved situation of the Newman--Unti group is highlighted, which will be studied in future work.

scholarly journals Asymptotic symmetry of four dimensional Einstein-Yang-Mills and Einstein-Maxwell theory

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Nabamita Banerjee ◽  
Tabasum Rahnuma ◽  
Ranveer Kumar Singh
Keyword(s):  
Asymptotic Symmetry ◽  
Maxwell Theory ◽  
Asymptotically Flat ◽  
Yang Mills ◽  
Alternative Approach ◽  
Pure Gravity ◽  
Asymptotic Symmetries ◽  
Symmetry Algebras

Abstract Asymptotic symmetry plays an important role in determining physical observables of a theory. Recently, in the context of four dimensional asymptotically flat pure gravity and $$ \mathcal{N} $$ N = 1 supergravity, it has been proposed that OPEs of appropriate celestial amplitudes can be used to find their asymptotic symmetries. In this paper we find the asymptotic symmetry algebras of four dimensional Einstein-Yang-Mills and Einstein-Maxwell theories using this alternative approach, namely using the OPEs of their respective celestial amplitudes. The algebra obtained here are in agreement with the known results in the literature.

scholarly journals Light-ray operators, detectors and gravitational event shapes

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Riccardo Gonzo ◽  
Andrzej Pokraka
Keyword(s):  
Classical Limit ◽  
Compact Objects ◽  
Einstein Equations ◽  
Direct Connection ◽  
Leading Order ◽  
Null Infinity ◽  
Quantum Operator ◽  
Wave Event ◽  
Event Shapes ◽  
Celestial Sphere

Abstract Light-ray operators naturally arise from integrating Einstein equations at null infinity along the light-cone time. We associate light-ray operators to physical detectors on the celestial sphere and we provide explicit expressions in perturbation theory for their hard modes using the steepest descent technique. We then study their algebra in generic 4-dimensional QFTs of massless particles with integer spin, comparing with complexified Cordova-Shao algebra. For the case of gravity, the Bondi news squared term provides an extension of the ANEC operator at infinity to a shear-inclusive ANEC, which as a quantum operator gives the energy of all quanta of radiation in a particular direction on the sky. We finally provide a direct connection of the action of the shear-inclusive ANEC with detector event shapes and we study infrared-safe gravitational wave event shapes produced in the scattering of massive compact objects, computing the energy flux at infinity in the classical limit at leading order in the soft expansion.

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