ParticleTemplate (Python)

The ParticleTemplate Cython class is the Python-side wrapper around the C++ particle_template. User particle classes must subclass it and override Type to set the ROOT branch prefix.

Constructor

ParticleTemplate(inpt=None) — default-constructs the underlying C++ object. Pass a serialised dict (from __reduce__) to restore a saved state.

Operators / Special Methods

Signature	Description
`__add__(other: ParticleTemplate) → ParticleTemplate`	Return a new particle whose four-momentum is the sum of `self` and `other`. Children and Parents lists are merged.
`__iadd__(other: ParticleTemplate) → ParticleTemplate`	Add `other`’s four-momentum into `self` in-place and merge its Children and Parents.
`__eq__(other) → bool`	Equality based on the C++ `operator==` (compares all four-momentum components and flags).
`__hash__() → int`	Integer hash derived from the first 8 hex digits of `self.hash`.
`is_self(inpt) → bool`	Return `True` if `inpt` is an instance or subclass of `ParticleTemplate`.
`clone() → ParticleTemplate`	Return a new default-constructed instance of the same concrete subclass with the same `Type` string.
`DeltaR(other: ParticleTemplate) → float`	Compute angular separation \(\Delta R = \sqrt{(\Delta\eta)^2 + (\Delta\phi)^2}\).
`dump(path, name) / load(path, name)`	Pickle serialise / restore the particle to/from `path/name.pkl`.

Kinematic Properties (read/write)

Property	Type	Description
`px`	`float`	Cartesian x-momentum in MeV.
`py`	`float`	Cartesian y-momentum in MeV.
`pz`	`float`	Cartesian z-momentum in MeV.
`e`	`float`	Energy in MeV.
`pt`	`float`	Transverse momentum.
`eta`	`float`	Pseudorapidity.
`phi`	`float`	Azimuthal angle in radians.
`Mass`	`float`	Invariant mass in MeV (computed on demand, `nan` until set).
`charge`	`float`	Electric charge.
`pdgid`	`int`	PDG particle ID code.
`symbol`	`str`	Particle symbol string (e.g. `"t"` for top quark).
`Type`	`str`	ROOT branch type prefix. Must be set by each concrete subclass. Used by `apply_type_prefix()` to build full branch names.
`index`	`int`	Sequential particle index within the event (read from `particle_t.index`).

Flag Properties (read/write)

Property	Type	Description
`is_lep`	`bool`	`True` if this particle is classified as a lepton.
`is_nu`	`bool`	`True` if this particle is classified as a neutrino.
`is_b`	`bool`	`True` if this particle is classified as a b-quark/jet.
`is_add`	`bool`	`True` if this particle is an additional (non-prompt) particle. Default is `True`.
`LeptonicDecay`	`bool`	`True` if this particle decays leptonically.
`lepdef`	`list[int]`	PDG IDs that define “lepton” for the `is_lep` test.
`nudef`	`list[int]`	PDG IDs that define “neutrino” for the `is_nu` test.

Topology Properties

Property	Type	Description
`Children`	`list[ParticleTemplate]`	List of child particles registered via `register_child`.
`Parents`	`list[ParticleTemplate]`	List of parent particles registered via `register_parent`.
`hash`	`str`	18-character unique hex identifier (`"0x"` + 16 hex digits).

Leaf Registration Methods (inherited usage)

These C++ methods are called from the subclass build override via self.ptr:

Method	Description
`add_leaf(key: bytes, leaf: bytes)`	Map a property name key to a ROOT branch suffix leaf. Call `apply_type_prefix()` after all leaves are registered to prepend the `Type` prefix.
`apply_type_prefix()`	Prepend `Type` to every registered leaf name. After this call a leaf registered as `b"_pt"` becomes `b"top_pt"` when `Type == "top"`.