61 citations · 318 across the 20 of their papers we have counts for
21 papers
Steinmann Violation and Minimal Cuts
Holmfridur S. Hannesdottir, Luke Lippstreu, Andrew J. McLeod +1
The Steinmann relations are known to be violated with respect to some -- but not all -- two-particle momentum channels in massless Feynman integrals. We trace the source of this St…
Tracking discontinuities in parameter space
Ruth Britto, Holmfridur S. Hannesdottir
We develop a geometric framework in Feynman-parameter space to determine constraints on the sequential discontinuities of Feynman integrals. Our method is based on tracking the def…
Soft Factorisation and Exponentiation from Schwinger-Space Geometry
Carolina Figueiredo, Giulio Gambuti, Holmfridur S. Hannesdottir
Infrared divergences in Quantum Field Theory govern the low-energy dynamics of many physical theories, and their understanding is a crucial ingredient in predicting the outcomes of…
Records from the S-Matrix Marathon: Asymptotic Observables
Simon Caron-Huot, Mathieu Giroux, Holmfridur S. Hannesdottir +2
These lectures introduce the notion of asymptotic observables, which are classes of measurable quantities predicted by quantum field theory. In gapped theories with trivial infrare…
Records from the S-Matrix Marathon: Gravitational Physics from Scattering Amplitudes
Miguel Correia, Holmfridur S. Hannesdottir, Giulia Isabella +5
These lecture notes explain how classical gravitational physics emerges from scattering amplitudes. We emphasize the role of different kinematic regimes in probing various aspects…
Records from the S-Matrix Marathon: Tasty Bits of Several Complex Variables
Sean N. Curry, Jiří Lebl, Mathieu Giroux +3
We will cover the basics of several complex variables in 4 lectures: Basic properties of holomorphic functions in several variables, the notion of pseudoconvexity, CR functions and…
Records from the S-Matrix Marathon: A Timeless History of Time
Mang Hei Gordon Lee, Enrico Pajer, Mathieu Giroux +3
By directly probing the initial conditions of our universe, cosmological surveys offer us a unique observational handle on quantum field theory in curved spacetime with dynamical g…
The Landau Bootstrap
Holmfridur Hannesdottir, Andrew McLeod, Matthew D. Schwartz +1
We advocate a strategy of bootstrapping Feynman integrals from just knowledge of their singular behavior. This approach is complementary to other bootstrap programs, which exploit…
Records from the S-Matrix Marathon: Observables in Expanding Universes
Paolo Benincasa, Mathieu Giroux, Holmfridur S. Hannesdottir +3
Observables in expanding universes are crucial to understand the physics of the early universe. In these lectures, we review some recent progress in understanding their mathematica…
Minimal Cuts and Genealogical Constraints on Feynman Integrals
Holmfridur S. Hannesdottir, Luke Lippstreu, Andrew J. McLeod +1
We introduce an efficient method for deriving hierarchical constraints on the discontinuities of individual Feynman integrals. This method can be applied at any loop order and part…
Cutting-Edge Tools for Cutting Edges
Ruth Britto, Claude Duhr, Holmfridur S. Hannesdottir +1
We review different notions of cuts appearing throughout the literature on scattering amplitudes. Despite similar names, such as unitarity cuts or generalized cuts, they often repr…
Crossing beyond scattering amplitudes
Simon Caron-Huot, Mathieu Giroux, Holmfridur S. Hannesdottir +1
We find that different asymptotic measurements in quantum field theory can be related to one another through new versions of crossing symmetry. Assuming analyticity, we conjecture…
What can be measured asymptotically?
Simon Caron-Huot, Mathieu Giroux, Holmfridur S. Hannesdottir +1
We consider asymptotic observables in quantum field theories in which the S-matrix makes sense. We argue that in addition to scattering amplitudes, a whole compendium of inclusive…
Constraints on Sequential Discontinuities from the Geometry of On-shell Spaces
Holmfridur S. Hannesdottir, Andrew J. McLeod, Matthew D. Schwartz +1
We present several classes of constraints on the discontinuities of Feynman integrals that go beyond the Steinmann relations. These constraints follow from a geometric formulation…
Prospects for strong coupling measurement at hadron colliders using soft-drop jet mass
Holmfridur S. Hannesdottir, Aditya Pathak, Matthew D. Schwartz +1
We compute the soft-drop jet-mass distribution from collisions to NNLL accuracy while including nonperturbative corrections through a field-theory based formalism. Using these…
What is the for the S-matrix?
Holmfridur S. Hannesdottir, Sebastian Mizera
Can the S-matrix be complexified in a way consistent with causality? Since the 1960's, the affirmative answer to this question has been well-understood for scattering of…
Implications of the Landau Equations for Iterated Integrals
Holmfridur S. Hannesdottir, Andrew J. McLeod, Matthew D. Schwartz +1
We introduce a method for deriving constraints on the symbol of Feynman integrals from the form of their asymptotic expansions in the neighborhood of Landau loci. In particular, we…
Sequential Discontinuities of Feynman Integrals and the Monodromy Group
Jacob L. Bourjaily, Holmfridur Hannesdottir, Andrew J. McLeod +2
We generalize the relation between discontinuities of scattering amplitudes and cut diagrams to cover sequential discontinuities (discontinuities of discontinuities) in arbitrary m…
An -Matrix for Massless Particles
Holmfridur Hannesdottir, Matthew D. Schwartz
The traditional -matrix does not exist for theories with massless particles, such as quantum electrodynamics. The difficulty in isolating asymptotic states manifests itself as i…
A Finite -Matrix
Holmfridur Hannesdottir, Matthew D. Schwartz
When massless particles are involved, the traditional scattering matrix (-matrix) does not exist: it has no rigorous non-perturbative definition and has infrared divergences in…
Infrared Finiteness and Forward Scattering
Christopher Frye, Holmfridur Hannesdottir, Nisarga Paul +2
Infrared divergences have long been heralded to cancel in sufficiently inclusive cross-sections, according to the famous Kinoshita-Lee-Nauenberg theorem which mandates an initial a…