particle 0.7.1

Installation

Install particle like any other Python package:

pip install particle

or similar (use --user, virtualenv, etc. if you wish).

Strict dependencies

• Python (2.7+, 3.5+)

• importlib_resources backport if using Python < 3.7

• attrs provides classes without boilerplate (similar to DataClasses in Python 3.7)

• hepunits provides units for the Scikit-HEP packages

Changelog

See the changelog for a history of notable changes.

Getting started: PDGIDs

>>> from particle import PDGID
>>>
>>> pid = PDGID(211)
>>> pid
<PDGID: 211>
>>> pid.is_meson
True
>>> pid = PDGID(99999999)
>>> pid
<PDGID: 99999999 (is_valid==False)>

For convenience, all properties of the PDGID class are available as standalone functions:

>>> from particle.pdgid import is_meson
>>>
>>> is_meson(211)
True

PDGID literals provide (PDGID class) aliases for the most common particles, with easily recognisable names. For example:

>>> from particle.pdgid import literals as lid
>>>
>>> lid.pi_plus
<PDGID: 211>
>>>
>>> from particle.pdgid.literals import Lambda_b_0
>>> Lambda_b_0
<PDGID: 5122>
>>> Lambda_b_0.has_bottom
True

You can quickly display PDGID info from the command line with:

$ python -m particle pdgid 323
<PDGID: 323>
A              None
J              1.0
L              0
S              1
Z              None
abspid         323
charge         1.0
has_bottom     False
...

Similarly, classes exist to express identification codes used by MC programs, see information on converters below.

Getting started: Particles

You can use a variety of methods to get particles. If you know the PDGID number you can get a particle directly, or you can use a search:

>>> from particle import Particle
>>> Particle.from_pdgid(211)
<Particle: name="pi+", pdgid=211, mass=139.57061 ± 0.00024 MeV>
>>>
>>> Particle.findall('pi')[0]
<Particle: name="pi0", pdgid=111, mass=134.9770 ± 0.0005 MeV>

You can search for the properties using keyword arguments, which include pdg_name, name, mass, width, charge, three_charge, anti_flag, rank, I, J, G, P, quarks, status, mass_upper, mass_lower, width_upper, and width_lower. You can pass a callable or an exact match for any property. The argument particle can be set to True/False, as well, to limit the search to particles or antiparticles. You can also build the search yourself with the first positional argument, which accepts a callable that is given the particle object itself. If the first positional argument is a string, that will match against the particle’s name. The alternative .find() requires only one match returned by the search, and will throw an error if more or less than one match is found.

Here are possible sophisticated searches:

>>> # Print out all particles with asymmetric decay width uncertainties
>>> ps = Particle.findall(lambda p: p.width_lower != p.width_upper)
>>> for p in ps:
...     print(p.name, p.pdgid, p.width_lower, p.width_upper)
>>>
>>> # Find all antiparticles with 'Omega' in the name
>>> Particle.findall('Omega', particle=False)   # several found
>>>
>>> # Find all antiparticles of name=='Omega'
>>> Particle.findall(name='Omega', particle=False)  # none found
>>>
>>> # Find all antiparticles of pdg_name=='Omega'
>>> Particle.findall(pdg_name='Omega', particle=False)  # only 1, of course
[<Particle: name="Omega~+", pdgid=-3334, mass=1672.5 ± 0.3 MeV>]
>>>
>>> # Find all neutral beauty hadrons
>>> Particle.findall(lambda p: p.pdgid.has_bottom and p.charge==0)
>>>
>>> # Find all strange mesons with c*tau > 1 meter
>>> from hepunits import meter
>>> Particle.findall(lambda p: p.pdgid.is_meson and p.pdgid.has_strange and p.ctau > 1 * meter, particle=True)
[<Particle: name="K(L)0", pdgid=130, mass=497.611 ± 0.013 MeV>,
 <Particle: name="K+", pdgid=321, mass=493.677 ± 0.016 MeV>]

Once you have a particle, any of the properties can be accessed, along with several methods. Though they are not real properties, you can access is_name_barred, and spin_type. You can also .invert() a particle.

There are lots of printing choices for particles: describe(), programmatic_name, latex_name, html_name, HTML printing outs in notebooks, and of course repr and str support.

You can get the .pdgid from a particle, as well. Sorting particles will put lowest abs(PDGID) first.

Particle literals provide (Particle class) aliases for the most common particles, with easily recognisable names. For example:

>>> from particle.particle import literals as lp
>>> lp.pi_plus
<Particle: name="pi+", pdgid=211, mass=139.57061 ± 0.00024 MeV>
>>>
>>> from particle.particle.literals import Lambda_b_0
>>> Lambda_b_0
<Particle: name="Lambda(b)0", pdgid=5122, mass=5619.60 ± 0.17 MeV>
>>> Lambda_b_0.J
0.5

You can quickly search for particles from the command line with (note: quotes may be used/needed but only double quotes work as expected on Windows):

$ python -m particle search "K*0"
<Particle: name="K*(892)0", pdgid=313, mass=895.55 ± 0.20 MeV>
<Particle: name="K*(1680)0", pdgid=30313, mass=1718 ± 18 MeV>
<Particle: name="K*(1410)0", pdgid=100313, mass=1421 ± 9 MeV>

If you only select one particle, either by a search or by giving the PDGID number, you can see more information about the particle:

$ python -m particle search 311
Name: K0             ID: 311          Latex: $K^{0}$
Mass  = 497.611 ± 0.013 MeV
Width = -1.0 MeV
Q (charge)        = 0       J (total angular) = 0.0      P (space parity) = -
C (charge parity) = ?       I (isospin)       = 1/2      G (G-parity)     = ?
    SpinType: SpinType.PseudoScalar
    Quarks: dS
    Antiparticle name: K~0 (antiparticle status: Barred)

>>> from particle import Particle
>>> Particle.load_table('new_particles.csv', append=True)

$ python3 -m particle.particle.convert --help

Getting started: Converters

You can use mapping classes to convert between particle MC identification codes and particle names. See the particle.converters modules for the available mapping classes. For example:

>>> from particle.converters import Pythia2PDGIDBiMap
>>> from particle import PDGID, PythiaID
>>>
>>> pyid = Pythia2PDGIDBiMap[PDGID(9010221)]
>>> pyid
<PythiaID: 10221>

>>> pdgid = Pythia2PDGIDBiMap[PythiaID(10221)]
>>> pdgid
<PDGID: 9010221>

This code makes use of classes similar to PDGID, which hold particle identification codes used by MC programs. Possible use cases are the following:

>>> from particle import Particle
>>> from particle import GeantID, PythiaID
>>>
>>> geantid = GeantID(8)
>>> p = Particle.from_pdgid(geantid.to_pdgid())
>>>
>>> p = Particle.find(pdgid=geantid.to_pdgid())
>>> p.name
'pi+'

>>> pythiaid = PythiaID(211)
>>> p = Particle.from_pdgid(pythiaid.to_pdgid())

>>> p = Particle.find(pdgid=pythiaid.to_pdgid())
>>> p.name
'pi+'

Acknowledgements

Support for this work was provided by the National Science Foundation cooperative agreement OAC-1450377 (DIANA/HEP) and OAC-1836650 (IRIS-HEP). Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.