Conveners
Quantum Field & String Theory: Non-perturbativity and Amplitudes
- Seth Koren (University of Notre Dame)
Quantum Field & String Theory: Generalized Symmetries & Amplitudes
- Stephen Martin
Non-perturbative dynamics of gauge theories has been notoriously difficult to study. I discuss that supersymmetry slightly broken by anomaly mediation allows us to derive many features of dynamics. They include explicit demonstration of chiral symmetry breaking as well as monopole condensation, calculation of non-perturbative condensates, correct large $N_c$ behavior, and some of the low-lying spectra.
We find a complete set of 4-point vertices in the Constructive Standard Model (CSM) by satisfying perturbative unitarity. We use these and the 3-point vertices to calculate a comprehensive set of 4-point amplitudes in the CSM. We also introduce a package to numerically calculate phase-space points for constructive amplitudes and use it to validate the 4-point amplitudes against Feynman...
It is well known that in QFT, perturbative series expansions in powers of the coupling constant yield an asymptotic series. At weak coupling, this is not an issue, since the series is valid at lower orders and one can use it to make reliable predictions. However, the series fails completely at strong coupling. I will show that one can develop two different types of series expansions that are...
I will present some recent progress at the intersection between machine learning and field theories, highlighting Feynman diagram methods for neural network correlators and neural scaling laws.
First, building on a correspondence between neural network ensembles and statistical field theories, I will introduce a diagrammatic framework to calculate neural network correlators in the large-width...
The constructive method of determining amplitudes from on-shell pole structure has been shown to be promising for calculating amplitudes in a more efficient way. However, challenges have been encountered when a massless internal photon is involved in the gluing of three-point amplitudes with massive external particles. In this talk, I will describe how to use the original on-shell method,...
We demonstrate how the scattering amplitudes of some scalar theories, scaffolded general relativity, multi-flavor DBI, and the special Galileon, vanish at multiple loci in momentum space that include and extend their soft-limit behaviors. We elucidate the factorization of the amplitudes near the zero loci into lower point amplitudes. We explain how the occurrence of the zero loci in these...
Generalized global symmetries are present in theories of particle physics, and understanding their structure can give insight into these theories and UV completions thereof. We will identify non-invertible chiral symmetries in certain flavorful Z' extensions of the Standard Model, and this will lead us to interesting nonperturbative effects in theories of gauged non-Abelian flavor. For the...
We critically examine the applicability of the effective potential within dynamical situations, as it is often used in phenomenological models, and find in short, that the answer is negative. An important caveat of the use of an effective potential in dynamical equations of motion is an explicit violation of energy conservation.
We introduce an adiabatic effective potential in a consistent...
We study the dynamics of particle mixing induced by their coupling to a common intermediate state or decay channel, which is of broad fundamental interest within the context of CP violation and/or baryogenesis. Field mixing may also be a consequence of “portals”, connecting standard model degrees of freedom to hypothetical ones via mediator particles beyond the standard model. An effective...
We construct tree-level amplitude for massive particles using on-shell recursion relations based on two classes of momentum shifts: an all-line transverse shift that deforms momentum by its transverse polarization vector, and a massive BCFW-type shift. We illustrate that these shifts allow us to correctly calculate four-point and five-point amplitudes in massive QED, without an ambiguity...
We show in a very general setup that the linear entropy for the entanglement of a final state, resulting from a quantum 2 to 2 scattering of unentangled initial states in the plane wave limit, is twice of the scattering probability for certain outcomes. In particular, the entropy can be expressed as proportional to some scattering cross section, divided by an area that characterizes the spread...
Experiments conducted in the late 1950s and early 1960s provided compelling evidence that pions and kaons possess directional properties, challenging their traditional classification as pseudoscalar particles. In particular, four of these experiments, performed by four distinct research groups, each reported deviations exceeding five standard deviations from the expected result for...
