Usage

Usage#

Main interface#

Here are some quick examples of how to use qrules. For more fine-grained control, have a look at Advanced.

Investigate intermediate resonances#

import qrules

reaction = qrules.generate_transitions(
    initial_state="J/psi(1S)",
    final_state=["K0", "Sigma+", "p~"],
    allowed_interaction_types="strong",
    formalism="canonical-helicity",
)

import graphviz

dot = qrules.io.asdot(reaction, collapse_graphs=True)
graphviz.Source(dot)

../_images/755de53f4668ca9454b15cbe2773b3e45a31d8eb7242e21298655b3b151fae1b.svg

Next, you use the ampform package to convert these transitions into a mathematical description that you can use to fit your data and perform Partial Wave Analysis!

Quantum number search#

The load_pdg() function creates a ParticleCollection containing the latest PDG info. Its find() and filter() methods allows you to quickly look up the quantum numbers of a particle and, vice versa, look up particle candidates based on a set of quantum numbers.

import qrules

pdg = qrules.load_pdg()
pdg.find(22)  # by pid
pdg.find("Delta(1920)++")

Particle(
  name='Delta(1920)++',
  pid=22224,
  latex='\\Delta(1920)^{++}',
  spin=1.5,
  mass=1.92,
  width=0.3,
  charge=2,
  isospin=Spin(3/2, +3/2),
  baryon_number=1,
  parity=+1,
)

subset = pdg.filter(lambda p: p.spin in {2.5, 3.5, 4.5} and p.name.startswith("N"))
subset.names

['N(1675)~-',
 'N(1675)~0',
 'N(1675)0',
 'N(1675)+',
 'N(1680)~-',
 'N(1680)0',
 'N(1680)~0',
 'N(1680)+',
 'N(2190)~-',
 'N(2190)~0',
 'N(2190)0',
 'N(2190)+']

Tip

See Particle database

Check allowed reactions#

qrules can be used to check whether a transition between an initial and final state is violated by any conservation rules:

qrules.check_reaction_violations(
    initial_state="pi0",
    final_state=["gamma", "gamma", "gamma"],
)

{frozenset({'c_parity_conservation'})}

Advanced#

Each of the qrules’s sub-modules offer functionality to handle more advanced reaction types. The following notebooks illustrate how use them.