Splitting Ward identity

Safari, Mahmoud

doi:10.1140/epjc/s10052-016-4036-6

Cited by 33 publications

(49 citation statements)

References 71 publications

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“…In this work we do not only compare the avatars of the background Newton coupling to that of the fluctuation coupling, we also further improve the background coupling to a level-one coupling with the explicit use of a Nielsen identity. Related works on Nielsen identities in quantum gravity are [18][19][20][21][22][23][24][25][26][27]. We find that the effective universality that exists between the dynamical couplings is not present for the background and the level-one couplings.…”

Section: Introductionmentioning

confidence: 76%

Effective universality in quantum gravity

et al. 2018

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We investigate the asymptotic safety scenario for a scalar-gravity system. This system contains two avatars of the dynamical Newton coupling, a gravitational self-coupling and a scalar-graviton coupling. We uncover an effective universality for the dynamical Newton coupling on the quantum level: its momentum-dependent avatars are in remarkable quantitative agreement in the scaling regime of the UV fixed point. For the background Newton coupling, this effective universality is not present, but qualitative agreement remains. arXiv:1804.00012v2 [hep-th]

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Section: Introductionmentioning

confidence: 76%

Effective universality in quantum gravity

et al. 2018

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“…The effective action generates all one-particle-irreducible correlation functions and as such encodes the symmetries of the theory. Schematically, these identities read [6,20,26,83,[88][89][90][91][92][93][94] In both cases the Nielsen identity is a combination of a quantum equation of motion, the Dyson-Schwinger equation, and the Slavnov-Taylor identity (STI) or diffeomorphism constraint. The setup also entails that correlations of the fluctuation fields are necessarily backgrounddependent.…”

Section: Diffeomorphism Invariance and Background Independencementioning

confidence: 99%

Towards apparent convergence in asymptotically safe quantum gravity

2018

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The asymptotic safety scenario in gravity is accessed within the systematic vertex expansion scheme for functional renormalisation group flows put forward in Christiansen et al. (Phys Lett B 728:114, 2014 ), Christiansen et al. (Phy Rev D 93:044036, 2016 ), and implemented in Christiansen et al. (Phys Rev D 92:121501, 2015 ) for propagators and three-point functions. In the present work this expansion scheme is extended to the dynamical graviton four-point function. For the first time, this provides us with a closed flow equation for the graviton propagator: all vertices and propagators involved are computed from their own flows. In terms of a covariant operator expansion the current approximation gives access to , R , as well as and higher derivative operators. We find a UV fixed point with three attractive and two repulsive directions, thus confirming previous studies on the relevance of the first three operators. In the infrared we find trajectories that correspond to classical general relativity and further show non-classical behaviour in some fluctuation couplings. We also find signatures for the apparent convergence of the systematic vertex expansion. This opens a promising path towards establishing asymptotically safe gravity in terms of apparent convergence.

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“…where C(ḡ, h) is the expectation value of the (covariant) derivative of h(ḡ, g), for a discussion in the present FRG setting see [15,[82][83][84]. The NIs, (4) and (5), entail that in both cases the effective action is not a function of g =ḡ + h or g = g + f (ḡ, h) respectively.…”

Section: A Frg and Nielsen Identities For Gravitymentioning

confidence: 99%

Curvature dependence of quantum gravity

et al. 2018

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We investigate the phase diagram of quantum gravity with a vertex expansion about constantlycurved backgrounds. The graviton two-and three-point function are evaluated with a spectral sum on a sphere. We obtain, for the first time, curvature-dependent UV fixed point functions of the dynamical fluctuation couplings g * (R), µ * (R), and λ * 3 (R), and the background f (R)-potential. Based on these fixed point functions we compute solutions to the quantum and the background equation of motion with and without Standard Model matter. We have checked that the solutions are robust against changes of the truncation.

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Splitting Ward identity

Cited by 33 publications

References 71 publications

Effective universality in quantum gravity

Effective universality in quantum gravity

Towards apparent convergence in asymptotically safe quantum gravity

Curvature dependence of quantum gravity

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