CascadeDecays.jl
CascadeDecays.jl provides topology-aware routing for sequential decays: it stores a flat binary cascade graph, resolves bracket-addressed propagators and vertices, and maps event-dependent masses and helicity angles into local amplitude building blocks.
Getting started
- Define a cascade with
DecayTopology. - Attach propagators and vertices with
DecayChain. - Build runtime kinematics with
DecayChainKinematicsor the reusableKinematicTask/KinematicPointworkflow. - Evaluate amplitudes with
amplitude(chain, x)(full external-helicity array) oramplitude(..., external_two_λs)(one component). Useamplitude(chain, point)when relative Wigner alignments between topologies are required.
Documentation map
The pages below walk through the package in increasing scope — from internal indices through single-chain integration to multi-channel models and external validation.
| Topic | Page | What it covers |
|---|---|---|
| Topology and numbering | Topology and numbering | Bracket addresses, line and vertex indices, incidence matrix, propagator routing |
| Amplitude evaluation | Amplitude computation | Propagators, vertex couplings H = h × particle-2 phase, aligned chain assembly |
| Particle-2 phase tutorial | Why do we need the particle-2 phase? | A polarized angular distribution that fails when the Jacob–Wick particle-2 phase is omitted |
| Convention matching | Convention matching across amplitude frameworks | Form-factor normalisation, particle-2 phases, angle conventions, and a staged cross-framework validation procedure |
| Four-vector kinematics | Routing four-vectors | KinematicTask, KinematicPoint, frame conventions, Wigner alignment paths |
| Single-chain integration | Using a decay chain | End-to-end DecayChain walkthrough with a fixed B⁺ → D⁰D⁻π⁺K⁺ event |
| Multi-channel models | Building a full model for a decay | CascadeDecay container, named channels, toy spectra |
| ThreeBodyDecays: general | General relations and signs | Spinful final states, reference-angle phases, and residual signs |
| ThreeBodyDecays: COMPASS | COMPASS: three-pion meson amplitudes | Common orientation, explicit (13) to (31) angle swap, and reflectivity on the parent spin projection |
| API | API reference | Autogenerated docstrings |