Statut  Confirmé 
Série  COURS 
Domaines  astroph,grqc 
Date  Vendredi 12 Octobre 2018 
Heure  10:00 
Institut  IPHT 
Salle  Salle Claude Itzykson, Bât. 774 
Nom de l'orateur  Thibault Damour 
Prenom de l'orateur  
Addresse email de l'orateur  
Institution de l'orateur  IHES 
Titre  From Classical Gravity to Quantum Amplitudes (2/4) 
Résumé  The recent observation of gravitational wave signals from inspiralling and coalescing binary black holes has been significantly helped, from the theoretical side, by the availability of analytical results on the motion and gravitational radiation of binary systems. \par The course will deal with the Effective OneBody (EOB) theory of the motion and radiation of binary systems, and explain the links between this formalism and various classical and quantum approaches to gravitationally interacting twobody systems, from traditional postNewtonian computations of the effective twobody action to quantum gravitational scattering amplitudes. \par The following analytical techniques will be reviewed ab initio: \\ 1  Matched Asymptotic Expansions approach to the motion of black holes and neutron stars; \\ 2  postNewtonian theory of the motion of point particles; \\ 3  Multipolar postMinkowskian theory of the gravitational radiation of general sources; \\ 4  Effective OneBody (EOB) theory of the motion and radiation of binary systems. \par The EOB formalism was initially based on a resummation of postNewtonianexpanded results. The postNewtonian approach assumes small gravitational potentials and small velocities, and loses its validity during the last orbits before the merger of black holes. The resummed EOB approach was able to extend the validity of the postNewtonian description of the motion and radiation of binary black holes to the strongfield, highvelocity regime reached during the last orbits, and the merger. EOB theory initially used a dictionary to translate postNewtonianexpanded results on (slowmotion) bound states of gravitationally interacting binary systems into the (resummed) Hamiltonian of a particle moving in an effective external gravitational field. \par The second part of the course will present the recent extension of EOB theory to the description of (classical) scattering states within the postMinkowskian approach which does not assume that velocities are small. This led to new insights in the highenergy limit of gravitational scattering and opened the way to transcribe quantum gravitational scattering amplitudes into their EOB Hamiltonian description. For instance, some twoloop ultra highenergy quantum scattering results of Amati, Ciafaloni and Veneziano could be transcribed into an improved knowledge of the highenergy limit of the classical gravitational interaction of two black holes. This leads also to interesting predictions about a linearReggetrajectory behavior of highangularmomenta, highenergy circular orbits. 
Numéro de preprint arXiv  
Commentaires  https://courses.ipht.cnrs.fr/?q=en/node/220 
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