Zobrazeno 1 - 10
of 5 377
pro vyhledávání: '"Speziale A"'
Autor:
Ashtekar, Abhay, Speziale, Simone
We introduce a Hamiltonian framework tailored to degrees of freedom (DOF) of field theories that reside in suitable 3-dimensional open regions, and then apply it to the gravitational DOF of general relativity. Specifically, these DOF now refer to ope
Externí odkaz:
http://arxiv.org/abs/2407.03254
Autor:
Rignon-Bret, Antoine, Speziale, Simone
We propose a new set of BMS charges at null infinity, characterized by a super-translation flux that contains only the `hard' term. This is achieved with a specific corner improvement of the symplectic 2-form, and we spell the conditions under which
Externí odkaz:
http://arxiv.org/abs/2405.08808
Autor:
Rignon-Bret, Antoine, Speziale, Simone
We show that when the Wald-Zoupas prescription is implemented, the resulting charges realize the BMS symmetry algebra without any 2-cocycle nor central extension, at any cut of future null infinity. We refine the covariance prescription for applicati
Externí odkaz:
http://arxiv.org/abs/2405.01526
Autor:
Rignon-Bret, Antoine, Speziale, Simone
In general relativity as well as gauge theories, non-trivial symmetries can appear at boundaries. In the presence of radiation some of the symmetries are not Hamiltonian vector fields, hence the definition of charges for the symmetries becomes delica
Externí odkaz:
http://arxiv.org/abs/2403.00730
Autor:
Ashtekar, Abhay, Speziale, Simone
Null infinity arises as a boundary of the Penrose conformal completion of an asymptotically flat physical space-time. We first note that null infinity is a weakly isolated horizon (WIH), and then show that its familiar properties can be derived from
Externí odkaz:
http://arxiv.org/abs/2402.17977
Autor:
Ashtekar, Abhay, Speziale, Simone
Publikováno v:
Phys. Rev. D109, L061501 (2024)
Black hole horizons in equilibrium and null infinity of asymptotically flat space-times are null 3-manifolds but have very different physical connotations. We first show that they share a large number of geometric properties, making them both weakly
Externí odkaz:
http://arxiv.org/abs/2401.15618
Lessons from discrete light-cone quantization for physics at null infinity: Bosons in two dimensions
Motivated by issues in the context of asymptotically flat spacetimes at null infinity, we discuss in the simplest example of a massless scalar field in two dimensions several subtleties that arise when setting up the canonical formulation on a single
Externí odkaz:
http://arxiv.org/abs/2401.14873
Autor:
Engle, Jonathan, Speziale, Simone
Publikováno v:
In: Bambi, C., Modesto, L., Shapiro, I. (eds) Handbook of Quantum Gravity. Springer, Singapore (2023)
Spinfoams provide a framework for the dynamics of loop quantum gravity that is manifestly covariant under the full four-dimensional diffeomorphism symmetry group of general relativity. In this way they complete the ideal of three-dimensional diffeomo
Externí odkaz:
http://arxiv.org/abs/2310.20147
We perform a detailed study of the covariance properties of the symplectic potential of general relativity on a null hypersurface, and of the different polarizations that can be used to study conservative as well as leaky boundary conditions. This al
Externí odkaz:
http://arxiv.org/abs/2309.03854
Publikováno v:
Open Access Journal of Clinical Trials, Vol 2014, Iss default, Pp 17-27 (2014)
Markus van der Giet,1 Josep M Cruzado,2 Johan W de Fijter,3 Hallvard Holdaas,4 Zailong Wang,5 Antonio Speziale,6 Guido Junge61Department of Nephrology, Campus Benjamin Franklin, Charite'-Universitätsmedizin, Berlin, Germany; 2Department of Nephrolog
Externí odkaz:
https://doaj.org/article/2b8a1685bcc547c999fe5ad96db89b0d