Introduction
The Reactions package allows to define a work with trees of processes among different elements. These processes can be either a reaction, where one or more reactants generate a set of products; or a decay, where a single element generates a set of products. The current implementation allows to work directly with named objects (where each element is identified by a string); with PDG elements, using the information from the PDG database; and with NuBase elements, using the information from the NuBase database. In the last two cases, objects can be accessed either by name or by PDG/NuBase ID, respectively.
import reactions
reactions.string_element('A') # by string
reac = reactions.reaction('A B -> C D E F')
assert len(reac.reactants) == 2
assert len(reac.products) == 4
dec = reactions.decay('A -> B C')
assert dec.head.name == 'A'
assert len(dec.products) == 2
reactions.decay('pi+ -> mu+ nu(mu)', kind='pdg') # use the PDG database
reactions.decay('1n -> 1H e-', kind='nubase') # use the NuBase database
The keyword argument kind determines what kind of elements will constitute the reaction/decay. String elements are considered by default. This package also provides the function is_element, which allows to check if a node in a reaction/decay tree is an element or not.
Reaction, decay and element objects can be compared. In the two first cases, the check is done recursively in the tree on a non-order sensitive basis, so A -> B C is the same as A -> C B.
assert reactions.decay('A -> B C') == reactions.decay('A -> C B')
It is possible to check the syntax of several reactions and/or decays executing the package as a script
python -m reactions check-syntax --decays 'A -> B C' --reactions 'A B -> C D' --kind string
python -m reactions check-syntax --decays 'K(S)0 -> pi+ pi-' --reactions 'e+ e- -> gamma gamma' --kind pdg
python -m reactions check-syntax --decays '1n -> 1H e-' --reactions '2H 2H -> 4He' --kind nubase
You can check the script options invoking:
python -m reactions --help
This package is also available in C++, and the documentation can be visited here.
The documentation covers the following aspects: