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SUMMARY:From Classical Gravity to Quantum Amplitudes
DTSTART;VALUE=DATE-TIME:20181019T121500Z
DTEND;VALUE=DATE-TIME:20181019T143000Z
DTSTAMP;VALUE=DATE-TIME:20200807T162234Z
UID:indico-event-3867@indico.math.cnrs.fr
DESCRIPTION:\n\n\nThe recent observation of gravitational wave signals fro
m inspiralling and coalescing binary black holes has been significantly he
lped\, from the theoretical side\, by the availability of analytical resul
ts on the motion and gravitational radiation of binary systems.\n\nThe cou
rse will deal with the Effective One-Body (EOB) theory of the motion and r
adiation of binary systems\, and explain the links between this formalism
and various classical and quantum approaches to gravitationally interactin
g two-body systems\, from traditional post-Newtonian computations of the e
ffective two-body action to quantum gravitational scattering amplitudes.\n
\nThe following analytical techniques will be reviewed ab initio:\n\n\n Ma
tched Asymptotic Expansions approach to the motion of black holes and neut
ron stars\;\n post-Newtonian theory of the motion of point particles\;\n M
ultipolar post-Minkowskian theory of the gravitational radiation of genera
l sources\;\n Effective One-Body (EOB) theory of the motion and radiation
of binary systems.\n\n\nThe EOB formalism was initially based on a resumma
tion of post-Newtonian-expanded results. The post-Newtonian approach assum
es small gravitational potentials and small velocities\, and loses its val
idity during the last orbits before the merger of black holes. The resumme
d EOB approach was able to extend the validity of the post-Newtonian descr
iption of the motion and radiation of binary black holes to the strong-fie
ld\, high-velocity regime reached during the last orbits\, and the merger.
EOB theory initially used a dictionary to translate post-Newtonian-expand
ed results on (slow-motion) bound states of gravitationally interacting bi
nary systems into the (resummed) Hamiltonian of a particle moving in an ef
fective external gravitational field.\n\nThe second part of the course wil
l present the recent extension of EOB theory to the description of (classi
cal) scattering states within the post-Minkowskian approach which does not
assume that velocities are small. This led to new insights in the high-en
ergy limit of gravitational scattering and opened the way to transcribe qu
antum gravitational scattering amplitudes into their EOB Hamiltonian descr
iption. For instance\, some two-loop ultra high-energy quantum scattering
results of Amati\, Ciafaloni and Veneziano could be transcribed into an im
proved knowledge of the high-energy limit of the classical gravitational i
nteraction of two black holes. This leads also to interesting predictions
about a linear-Regge-trajectory behavior of high-angular-momenta\, high-en
ergy circular orbits.\n\n\n\n\nhttps://indico.math.cnrs.fr/event/3867/
LOCATION:IPhT Salle Claude Itzykson
URL:https://indico.math.cnrs.fr/event/3867/
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