Signatures of Ultralight Bosons in the Orbital Eccentricity of Binary Black Holes.

We show that the existence of clouds of ultralight particles surrounding black holes during their cosmological history as members of a binary system can leave a measurable imprint on the distribution of masses and orbital eccentricities observable with future gravitational-wave detectors. Notably, we find that for nonprecessing binaries with chirp masses M≲10M_{⊙}, formed exclusively in isolation, larger-than-expected values of the eccentricity, i.e.

Local in Time Conservative Binary Dynamics at Fourth Post-Minkowskian Order.

Leveraging scattering information to describe binary systems in generic orbits requires identifying local and nonlocal in time tail effects. We report here the derivation of the universal (nonspinning) local in time conservative dynamics at fourth post-Minkowskian order, i.e.

Radiation Reaction and Gravitational Waves at Fourth Post-Minkowskian Order.

We obtain the total impulse in the scattering of nonspinning binaries in general relativity at fourth post-Minkowskian order, i.e., O(G^{4}), including linear, nonlinear, and hereditary radiation-reaction effects.

Conservative Dynamics of Binary Systems at Fourth Post-Minkowskian Order in the Large-Eccentricity Expansion.

We compute the conservative dynamics of nonspinning binaries at fourth post-Minkowskian order in the large-eccentricity limit, including both potential and radiation-reaction tail effects. This is achieved by obtaining the scattering angle in the worldline effective field theory approach and deriving the bound radial action via analytic continuation. The associated integrals are bootstrapped to all orders in velocities through differential equations, with boundary conditions in the potential and radiation regions.

Conservative Dynamics of Binary Systems to Third Post-Minkowskian Order from the Effective Field Theory Approach.

We derive the conservative dynamics of nonspinning binaries to third post-Minkowskian order, using the effective field theory (EFT) approach introduced in [G. Kälin and R. A.

Signals of a Quantum Universe.

Structure in the Universe is widely believed to have originated from quantum fluctuations during an early epoch of accelerated expansion. Yet, the patterns we observe today do not distinguish between quantum or classical primordial fluctuations; current cosmological data are consistent with either possibility. We argue here that a detection of primordial non-Gaussianity can resolve the present situation, and provide a litmus test for the quantum origin of cosmic structure.

Falsifying models of new physics via WW scattering.

We show that the coefficients of operators in the electroweak chiral Lagrangian can be bounded if the underlying theory obeys the usual assumptions of Lorentz invariance, analyticity, unitarity, and crossing to arbitrarily short distances. Violations of these bounds can be explained by either the existence of new physics below the naive cutoff of the effective theory, or by the breakdown of one of these assumptions in the short distance theory. As a corollary, if no light resonances are found, then a measured violation of the bound would falsify generic models of string theory.

Calculation of the first nonlinear contribution to the general-relativistic spin-spin interaction for binary systems.

We use recently developed effective field theory techniques to calculate the third order post-Newtonian correction to the spin-spin potential between two spinning objects. This correction represents the first contribution to the spin-spin interaction due to the nonlinear nature of general relativity and will play an important role in forthcoming gravity wave experiments.

Realistic clocks, universal decoherence, and the black hole information paradox.

Ordinary quantum mechanics is formulated on the basis of the existence of an ideal classical clock external to the system under study. This is clearly an idealization. As emphasized originally by Salecker and Wigner and more recently by others, there exist limits in nature to how "classical" even the best possible clock can be.