TY - JOUR

T1 - The eikonal operator at arbitrary velocities I

T2 - the soft-radiation limit

AU - Di Vecchia, Paolo

AU - Heissenberg, Carlo

AU - Russo, Rodolfo

AU - Veneziano, Gabriele

PY - 2022/7/7

Y1 - 2022/7/7

N2 - Observables related to the real part of the gravitational eikonal, such as the deflection angle and time delay, have been found so far to have a smooth post-Minkowskian (PM) expansion whose validity extends from the non-relativistic to the most extreme ultra-relativistic (UR) regime, which smoothly connects with massless particle collisions. To describe gravitational radiation, the eikonal phase has to be promoted to a unitary operator for which we motivate a proposal and start discussing properties in the soft-radiation limit. A convergent PM expansion is found to only hold below an UR bound (discussed in the GR literature in the seventies) above which a different expansion is instead needed implying, in general, some non-analyticity in Newton's constant. In this extreme UR regime soft radiative observables receive contributions only from gravitons and are therefore universal. This generalises the pattern discussed in [1] beyond the elastic case.

AB - Observables related to the real part of the gravitational eikonal, such as the deflection angle and time delay, have been found so far to have a smooth post-Minkowskian (PM) expansion whose validity extends from the non-relativistic to the most extreme ultra-relativistic (UR) regime, which smoothly connects with massless particle collisions. To describe gravitational radiation, the eikonal phase has to be promoted to a unitary operator for which we motivate a proposal and start discussing properties in the soft-radiation limit. A convergent PM expansion is found to only hold below an UR bound (discussed in the GR literature in the seventies) above which a different expansion is instead needed implying, in general, some non-analyticity in Newton's constant. In this extreme UR regime soft radiative observables receive contributions only from gravitons and are therefore universal. This generalises the pattern discussed in [1] beyond the elastic case.

KW - Black Holes

KW - Classical Theories of Gravity

KW - Scattering Amplitudes

KW - Supergravity Models

KW - GRAVITATIONAL-WAVES

KW - BREMSSTRAHLUNG

KW - GENERATION

KW - DERIVATION

KW - ENCOUNTERS

KW - PHOTONS

U2 - 10.1007/JHEP07(2022)039

DO - 10.1007/JHEP07(2022)039

M3 - Journal article

VL - 2022

JO - Journal of High Energy Physics (Online)

JF - Journal of High Energy Physics (Online)

SN - 1126-6708

IS - 7

M1 - 039

ER -