55 research outputs found
Tidal Effects in the Post-Minkowskian Expansion
Tools from scattering amplitudes and effective field theory have recently
been repurposed to derive state-of-the-art results for the black hole binary
inspiral in the post-Minkowskian expansion. In the present work we extend this
approach to include the tidal effects of mass and current quadrupoles on the
conservative dynamics of non-spinning neutron star mergers. We compute the
leading and, for the first time, next-to-leading order post-Minkowskian finite
size corrections to the conservative Hamiltonian, together with their
associated scattering amplitudes and scattering angles. Our expressions are
gauge invariant and, in the extreme mass ratio limit, consistent with the
dynamics of a tidally deformed test body in a Schwarzschild background.
Furthermore, they agree completely with existing results at leading
post-Minkowskian and second post-Newtonian orders.Comment: 5 pages + references, 1 figure, 1 ancillary fil
Classical gravitational scattering at O(G³) from Feynman diagrams
We perform a Feynman diagram calculation of the two-loop scattering amplitude for gravitationally interacting massive particles in the classical limit. Conveniently, we are able to sidestep the most taxing diagrams by exploiting the test-particle limit in which the system is fully characterized by a particle propagating in a Schwarzschild spacetime. We assume a general choice of graviton field basis and gauge fixing that contains as a subset the well-known deDonder gauge and its various cousins. As a highly nontrivial consistency check, all gauge parameters evaporate from the final answer. Moreover, our result exactly matches that of Bern et al. [39], here verified up to sixth post-Newtonian order while also reproducing the same unique velocity resummation at third post-Minkowksian order
Classical gravitational scattering at O(G³) from Feynman diagrams
We perform a Feynman diagram calculation of the two-loop scattering amplitude for gravitationally interacting massive particles in the classical limit. Conveniently, we are able to sidestep the most taxing diagrams by exploiting the test-particle limit in which the system is fully characterized by a particle propagating in a Schwarzschild spacetime. We assume a general choice of graviton field basis and gauge fixing that contains as a subset the well-known deDonder gauge and its various cousins. As a highly nontrivial consistency check, all gauge parameters evaporate from the final answer. Moreover, our result exactly matches that of Bern et al. [39], here verified up to sixth post-Newtonian order while also reproducing the same unique velocity resummation at third post-Minkowksian order
The Trispectrum in the Effective Field Theory of Large Scale Structure
We compute the connected four point correlation function (the trispectrum in
Fourier space) of cosmological density perturbations at one-loop order in
Standard Perturbation Theory (SPT) and the Effective Field Theory of Large
Scale Structure (EFT of LSS). This paper is a companion to our earlier work on
the non-Gaussian covariance of the matter power spectrum, which corresponds to
a particular wavenumber configuration of the trispectrum. In the present
calculation, we highlight and clarify some of the subtle aspects of the EFT
framework that arise at third order in perturbation theory for general
wavenumber configurations of the trispectrum. We consistently incorporate
vorticity and non-locality in time into the EFT counterterms and lay out a
complete basis of building blocks for the stress tensor. We show predictions
for the one-loop SPT trispectrum and the EFT contributions, focusing on
configurations which have particular relevance for using LSS to constrain
primordial non-Gaussianity.Comment: 25+3 pages, 7 figure
Fermionic Glauber Operators and Quark Reggeization
We derive, in the framework of soft-collinear effective field theory (SCET),
a Lagrangian describing the -channel exchange of Glauber quarks in the Regge
limit. The Glauber quarks are not dynamical, but are incorporated through
non-local fermionic potential operators. These operators are power suppressed
in relative to those describing Glauber gluon exchange, but give the
first non-vanishing contributions in the Regge limit to processes such as
and . They therefore represent an
interesting subset of power corrections to study. The structure of the
operators, which describe certain soft and collinear emissions to all orders
through Wilson lines, is derived from the symmetries of the effective theory
combined with constraints from power and mass dimension counting, as well as
through explicit matching calculations. Lightcone singularities in the
fermionic potentials are regulated using a rapidity regulator, whose
corresponding renormalization group evolution gives rise to the Reggeization of
the quark at the amplitude level and the BFKL equation at the cross section
level. We verify this at one-loop, deriving the Regge trajectory of the quark
in the color channel, as well as the leading logarithmic BFKL equation.
Results in the and color channels are obtained by the
simultaneous exchange of a Glauber quark and a Glauber gluon. SCET with quark
and gluon Glauber operators therefore provides a framework to systematically
study the structure of QCD amplitudes in the Regge limit, and derive
constraints on higher order amplitudes.Comment: 31 pages, many figure
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