qrules
qrulesΒΆ
import qrules
A rule based system that facilitates particle reaction analysis.
QRules generates allowed particle transitions from a set of conservation rules and boundary conditions as specified by the user. The user boundary conditions for a particle reaction problem are for example the initial state, final state, and allowed interactions.
The core of qrules
computes which transitions (represented by a
StateTransitionGraph
) are allowed between a certain initial and final state.
Internally, the system propagates the quantum numbers defined by the
particle
module through the StateTransitionGraph
, while
satisfying the rules define by the conservation_rules
module. See
Generate transitions and Particle database.
Finally, the io
module provides tools that can read and write the objects of
this framework.
- check_reaction_violations(initial_state: Union[str, Tuple[str, Sequence[float]], Sequence[Union[str, Tuple[str, Sequence[float]]]]], final_state: Sequence[Union[str, Tuple[str, Sequence[float]]]], mass_conservation_factor: Optional[float] = 3.0, particle_db: Optional[ParticleCollection] = None, max_angular_momentum: int = 1, max_spin_magnitude: float = 2.0) Set[FrozenSet[str]] [source]ΒΆ
Determine violated interaction rules for a given particle reaction.
Warning
This function only guarantees to find P, C and G parity violations, if itβs a two body decay. If all initial and final states have the C/G parity defined, then these violations are also determined correctly.
- Parameters
initial_state β Shortform description of the initial state w/o spin projections.
final_state β Shortform description of the final state w/o spin projections.
mass_conservation_factor β Factor with which the width is multiplied when checking for
MassConservation
. Set toNone
in order to deactivate mass conservation.particle_db (Optional) β Custom
ParticleCollection
object. Defaults to theParticleCollection
returned byload_pdg
.max_angular_momentum β Maximum angular momentum over which to generate \(LS\)-couplings.
max_spin_magnitude β Maximum spin magnitude over which to generate \(LS\)-couplings.
- Returns
Set of least violating rules. The set can have multiple entries, as several quantum numbers can be violated. Each entry in the frozenset represents a group of rules that together violate all possible quantum number configurations.
Example
>>> import qrules >>> qrules.check_reaction_violations( ... initial_state="pi0", ... final_state=["gamma", "gamma", "gamma"], ... ) {frozenset({'c_parity_conservation'})}
See also
- generate_transitions(initial_state: Union[str, Tuple[str, Sequence[float]], Sequence[Union[str, Tuple[str, Sequence[float]]]]], final_state: Sequence[Union[str, Tuple[str, Sequence[float]]]], allowed_intermediate_particles: Optional[List[str]] = None, allowed_interaction_types: Optional[Union[str, Iterable[str]]] = None, formalism: str = 'canonical-helicity', particle_db: Optional[ParticleCollection] = None, mass_conservation_factor: Optional[float] = 3.0, max_angular_momentum: int = 2, max_spin_magnitude: float = 2.0, topology_building: str = 'isobar', number_of_threads: Optional[int] = None) ReactionInfo [source]ΒΆ
Generate allowed transitions between an initial and final state.
Serves as a facade to the
StateTransitionManager
(see Generate transitions).- Parameters
initial_state (list) β A list of particle names in the initial state. You can specify spin projections for these particles with a
tuple
, e.g.("J/psi(1S)", [-1, 0, +1])
. If spin projections are not specified, all projections are taken, so the example here would be equivalent to"J/psi(1S)"
.final_state (list) β Same as
initial_state
, but for final state particles.allowed_intermediate_particles (
list
, optional) β A list of particle states that you want to allow as intermediate states. This helps (1) filter out resonances and (2) speed up computation time.allowed_interaction_types β Interaction types you want to consider. For instance,
["s", "em"]
results inEM
andSTRONG
and["strong"]
results inSTRONG
.formalism (
str
, optional) β Formalism that you intend to use in the eventual amplitude model.particle_db (
ParticleCollection
, optional) β The particles that you want to be involved in the reaction. Usesload_pdg
by default. Itβs better to use a subset for larger reactions, because of the computation times. This argument is especially useful when you want to use your own particle definitions (see Particle database).mass_conservation_factor β Width factor that is taken into account for for the
MassConservation
rule.max_angular_momentum β Maximum angular momentum over which to generate angular momenta.
max_spin_magnitude β Maximum spin magnitude over which to generate spins.
topology_building (str) β
Technique with which to build the
Topology
instances. Allowed values are:"isobar"
: Isobar model (each state decays into two states)"nbody"
: Use one central node and connect initial and final states to it
number_of_threads β Number of cores with which to compute the allowed transitions. Defaults to the current value returned by
settings.NumberOfThreads.get()
.
An example (where, for illustrative purposes only, we specify all arguments) would be:
>>> import qrules >>> reaction = qrules.generate_transitions( ... initial_state="D0", ... final_state=["K~0", "K+", "K-"], ... allowed_intermediate_particles=["a(0)(980)", "a(2)(1320)-"], ... allowed_interaction_types=["e", "w"], ... formalism="helicity", ... particle_db=qrules.load_pdg(), ... topology_building="isobar", ... ) >>> len(reaction.transition_groups) 3 >>> len(reaction.transitions) 4
- load_default_particles() ParticleCollection [source]ΒΆ
Load the default particle list that comes with
qrules
.Runs
load_pdg
and supplements its output definitions from the fileadditional_definitions.yml
.
Submodules and Subpackages