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particle

A collection of particle info containers.

The particle module is the starting point of the expertsystem. Its main interface is the ParticleCollection, which is a collection of immutable Particle instances that are uniquely defined by their properties. As such, it can be used stand-alone as a database of quantum numbers (see Particle database).

The reaction module uses the properties of Particle instances when it computes which StateTransitionGraph s are allowed between an initial state and final state.

class GellmannNishijima

Bases: object

Collection of conversion methods using Gell-Mann–Nishijima.

The methods in this class use the Gell-Mann–Nishijima formula:

\[Q = I_3 + \frac{1}{2}(B+S+C+B'+T)\]

where \(Q\) is charge (computed), \(I_3\) is Spin.projection of isospin, \(B\) is baryon_number, \(S\) is strangeness, \(C\) is charmness, \(B'\) is bottomness, and \(T\) is topness.

static compute_charge(state: expertsystem.particle.Particle) → Optional[float]

Compute charge using the Gell-Mann–Nishijima formula.

If isospin is not None, returns the value \(Q\): computed with the Gell-Mann–Nishijima formula.

static compute_isospin_projection(charge: float, baryon_number: float, strangeness: float, charmness: float, bottomness: float, topness: float) → float

Compute isospin projection using the Gell-Mann–Nishijima formula.

See compute_charge, but then computed for \(I_3\).

class Parity(value: Union[float, int, str])

Bases: collections.abc.Hashable

Safe, immutable data container for parity.

__eq__(other: object) → bool

Return self==value.

property value

class Particle(name: str, pid: int, spin: float, mass: float, width: float = 0.0, charge: int = 0, isospin: Optional[expertsystem.particle.Spin] = None, strangeness: int = 0, charmness: int = 0, bottomness: int = 0, topness: int = 0, baryon_number: int = 0, electron_lepton_number: int = 0, muon_lepton_number: int = 0, tau_lepton_number: int = 0, parity: Optional[expertsystem.particle.Parity] = None, c_parity: Optional[expertsystem.particle.Parity] = None, g_parity: Optional[expertsystem.particle.Parity] = None)

Bases: object

Immutable container of data defining a physical particle.

A Particle is defined by the minimum set of the quantum numbers that every possible instances of that particle have in common (the “static” quantum numbers of the particle). A “non-static” quantum number is the spin projection. Hence Particle instances do not contain spin projection information.

Particle instances are uniquely defined by their quantum numbers and properties like mass. The name and pid are therefore just labels that are not taken into account when checking if two Particle instances are equal.

Note

As opposed to classes such as EdgeQuantumNumbers and NodeQuantumNumbers, the Particle class serves as an interface to the user (see Particle database).

__eq__(other)

Method generated by attrs for class Particle.

baryon_number: int

bottomness: int

c_parity: Optional[expertsystem.particle.Parity]

charge: int

charmness: int

electron_lepton_number: int

g_parity: Optional[expertsystem.particle.Parity]

is_lepton() → bool

isospin: Optional[expertsystem.particle.Spin]

mass: float

muon_lepton_number: int

name: str

parity: Optional[expertsystem.particle.Parity]

pid: int

spin: float

strangeness: int

tau_lepton_number: int

topness: int

width: float

class ParticleCollection(particles: Optional[Iterable[expertsystem.particle.Particle]] = None)

Bases: collections.abc.MutableSet

Searchable collection of immutable Particle instances.

__eq__(other: object) → bool

Return self==value.

add(value: expertsystem.particle.Particle) → None

Add an element.

discard(value: Union[expertsystem.particle.Particle, str]) → None

Remove an element. Do not raise an exception if absent.

filter(function: Callable[[expertsystem.particle.Particle], bool]) → expertsystem.particle.ParticleCollection

Search by Particle properties using a lambda function.

For example:

>>> from expertsystem import io
>>> pdg = io.load_pdg()
>>> subset = pdg.filter(
...     lambda p: p.mass > 1.8
...     and p.mass < 2.0
...     and p.spin == 2
...     and p.strangeness == 1
... )
>>> sorted(list(subset.names))
['K(2)(1820)+', 'K(2)(1820)0']

find(search_term: Union[int, str]) → expertsystem.particle.Particle

Search for a particle by either name (str) or PID (int).

property names

update(other: Iterable[expertsystem.particle.Particle]) → None

class Spin(magnitude: float, projection: float)

Bases: collections.abc.Hashable

Safe, immutable data container for spin with projection.

__eq__(other: object) → bool

Return self==value.

property magnitude

property projection

create_antiparticle(template_particle: expertsystem.particle.Particle, new_name: Optional[str] = None) → expertsystem.particle.Particle

create_particle(template_particle: expertsystem.particle.Particle, name: Optional[str] = None, pid: Optional[int] = None, mass: Optional[float] = None, width: Optional[float] = None, charge: Optional[int] = None, spin: Optional[float] = None, isospin: Optional[expertsystem.particle.Spin] = None, strangeness: Optional[int] = None, charmness: Optional[int] = None, bottomness: Optional[int] = None, topness: Optional[int] = None, baryon_number: Optional[int] = None, electron_lepton_number: Optional[int] = None, muon_lepton_number: Optional[int] = None, tau_lepton_number: Optional[int] = None, parity: Optional[int] = None, c_parity: Optional[int] = None, g_parity: Optional[int] = None) → expertsystem.particle.Particle

topology