Comments on Lorentz transformations, dressed asymptotic states and Hawking radiation

Javadinezhad, Reza; Kol, Uri; Porrati, Massimo

doi:10.1007/jhep01(2019)089

Cited by 39 publications

(81 citation statements)

References 44 publications

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“…Our results bring further evidence that Hawking radiation is not modified by soft hair implanted by supertranslating shock waves, at least not using the mechanisms analyzed here. It complements the results of [56] obtained from the perspective of dressing states with infrared soft hair. While these results are consistent with the soft hair conjecture [47], they do not provide a mechanism for correlating in a bijection soft and hard sectors.…”

Section: Resultssupporting

confidence: 75%

“…Such displacement memory leads to a shift of the canonical variable defined at I + that encodes the displacement memory and that is also shifted by BMS supertranslations. We conclude that the limiting advanced time v 0 (θ, φ) is a functional of the leading order matter fields and directly relates to displacement memory at null infinity, consistently with the analysis of [29,56]. In that regard, the existence of a generalization of the limiting advanced time v 0 in any dimension is consistent with the existence of the triangular relationship between supertranslations, displacement memory and soft theorems in any dimension at null infinity [72][73][74].…”

Section: Comments On Hawking Radiationsupporting

confidence: 78%

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Invariance of Unruh and Hawking radiation under matter-induced supertranslations

Compère

Long

Riegler

2019

J. High Energ. Phys.

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Matter fields are supertranslated upon crossing a shock wave, which leads to entanglement of the quantum vacuum between the two regions on either side of the shock wave. We probe this entanglement for a scalar field in a planar shock wave background by computing the Bogoliubov transformation between the inertial and uniformly accelerated observer. The resulting Bogoliubov coefficients are shown to reproduce the standard Unruh effect without dependence on the form factor of the shock wave. In contrast, excited states lead to observables that depend upon the form factor. In the context of nonspherical gravitational collapse, we comment that the angular dependence of the limiting advanced time leads to similar supertranslation effects that do not affect the Hawking spectrum but do affect scattering amplitudes.1 While a quantum completion of Einstein gravity in four-dimensional asymptotically flat spacetimes that would allow detailed computations is still far from reach, describing universal properties of Einstein gravity as a quantum low energy effective theory is possible with current techniques. The laws of black hole thermodynamics are early milestones in this endeavor, which, in particular, include Hawking's radiation and paradox [1] and the Bekenstein-Hawking area law [1][2][3]. Another universal result is the graviton dominance of high energy scattering at small deflection angles [4-8] that is described classically by a collision of shock waves [9]. Recently, a new universal property of gravity was uncovered in the infrared sector close to null infinity [10-12]: a triangular relationship exists between the displacement memory effect [13][14][15][16], the leading soft graviton theorem [17] and supertranslation asymptotic symmetries [18][19][20], see the reviews [21,22]. Displacement memory is caused by hard (i.e. finite energy) processes reaching null infinity that can be either a change of Bondi mass [13], null matter radiation [15,16] or gravitational waves [14]. Displacement memory effectively amounts to a shift of a canonical variable defined at null infinity by a supertranslation asymptotic symmetry [12]. As a result, hard processes at null infinity are accompanied by soft (i.e. infinitely low energy) processes that are mimicked by a zero energy process: a supertranslation asymptotic symmetry. This mimicking can arise because of the infrared limit taken at null infinity. In the bulk of spacetime, a supertranslation can be induced by a shock wave [23]. For planar shock waves, probes encounter a permanent displacement shift upon crossing. This has led to define the concept of soft radiation away from the infrared limit as (exactly zero energy) large diffeomorphisms (or large gauge transformations) acting in the bulk of spacetime. In particular, it led to the definition of black holes with soft hair implants . Furthermore, it has been pointed out that soft hair may bear on the black hole information paradox [12,25] and that quantum purity might be restored in principle by correlations between the hard and sof...

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Section: Resultssupporting

confidence: 75%

Section: Comments On Hawking Radiationsupporting

confidence: 78%

Invariance of Unruh and Hawking radiation under matter-induced supertranslations

Compère

Long

Riegler

2019

J. High Energ. Phys.

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“…Evidence that Hawking radiation is not modified by soft hair implanted by supertranslating shock waves comes from [86], at least using the mechanisms analyzed therein. Their results complement those of [87] obtained from the perspective of dressing states with soft hair where the authors showed that the spectrum of Hawking radiation (without backreaction) emitted in the Schwarzschild background is unchanged after including the dressing of asymptotic states with soft form factors. The relevance of soft hair to black hole entropy is still an open question.…”

Section: Discussionsupporting

confidence: 78%

Supertranslation hair of Schwarzschild black hole: a Wilson line perspective

Choi

Pradhan

Akhoury

2020

J. High Energ. Phys.

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We demonstrate within the quantum field theoretical framework that an asymptotic particle falling into the black hole implants soft graviton hair on the horizon, conforming with the classical proposal of Hawking, Perry and Strominger. A key ingredient to this result is the construction of gravitational Wilson line dressings of an infalling scalar field, carrying a definite horizon supertranslation charge. It is shown that a typical Schwarzschild state is degenerate, and can be labeled by different soft supertranslation hairs parametrized for radial trajectories by the mass and energy of the infalling particle and its asymptotic point of contact with the horizon. The supertranslation zero modes are also obtained in terms of zero-frequency graviton operators, and are shown to be the expected canonical partners of the linearized horizon charge that enlarge the horizon Hilbert space.

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“…If the coproduct was primitive the T T ot pq would be given purely by the eigenvalue T pq of the soft particle and likewise for the late quanta. This corresponds to the argument of [34][35][36][37], because the supertranslation charges conservation would constrain only soft particles. But in the case of κ-deformed BMS the total supertranslation charges of early and late quanta are also functions of the Poincaré momenta of the hard particles.…”

Section: Exchange Of Charge Between Soft and Hard Part During The Timmentioning

confidence: 97%

“…This argument was refuted in a series of papers [34], [35], [36], [37] where it is argued that soft hair could not resolve the black hole unitarity problem, because their time evolution is trivial and their conservation laws are automatically satisfied. The soft modes carrying them effectively decouple from the hard ones and moreover there is a canonical transformation which strips the hard modes from all the supertranslational charges.…”

Section: Exchange Of Charge Between Soft and Hard Part During The Timmentioning

confidence: 99%

κ-deformed BMS symmetry

et al. 2019

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We present the quantum κ-deformation of BMS symmetry, by generalizing the lightlike κ-Poincaré Hopf algebra. On the technical level our analysis relies on the fact that the lightlike κ-deformation of Poincaré algebra is given by a twist and the lightlike deformation of any algebra containing Poincaré as a subalgebra can be done with the help of the same twisting element. We briefly comment on the physical relevance of the obtained κ-BMS Hopf algebra as a possible asymptotic symmetry of quantum gravity.In the recent years there is a surge of interest in BMS symmetry at null infinity of asymptotically flat spacetimes [1], [2], [3]. This renewed interest in the seemingly exotic aspects of classical general relativity was fueled by the discovery of a surprising and close relationship between asymptotic symmetries and soft gravitons theorem [4] that, as it turned out, has its roots in Ward identities for supertranslations [5], [6]. Moreover, the gravitational memory effect [7] appears to be related to the two [8], so that there is a triangle of interrelationships, which vertices are BMS symmetry, Weinberg's soft graviton theorem, and the memory effect. The extensive discussion of these effects can be found in recent reviews [9] and [10].It has also been argued recently [11] that the similarity of null infinity and black hole horizon suggests that the charges associated with the BMS symmetry might be present at the black hole horizon, so that the black hole might have an infinite number of hairs, so-called soft hairs, in addition to the three classical one: mass, charge, and angular momentum. It was argued in [11] and [12] that the presence of these charges may help solving the black hole information paradox.In this letter we will investigate the properties of a κ-deformed generalization of the BMS symmetry. There are several reasons to be interested in such a generalization. The main one is that it is believed that investigations of κ-deformation might shed some light on the properties of elusive quantum gravity. The deformation parameter of κ-deformation of Poincaré algebra [13]-[17], see [18] for a recent review and more references, has dimension of mass, and therefore it is natural to identify it with Planck mass, or inverse Planck length, which in turn suggests a possible close relationship between this deformation and quantum gravity. In fact, it was shown in [19]

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Comments on Lorentz transformations, dressed asymptotic states and Hawking radiation

Cited by 39 publications

References 44 publications

Invariance of Unruh and Hawking radiation under matter-induced supertranslations

Invariance of Unruh and Hawking radiation under matter-induced supertranslations

Supertranslation hair of Schwarzschild black hole: a Wilson line perspective

κ-deformed BMS symmetry

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