ComPWA/qrules

Render state transition solutions as J^PC(I^G)

Closed this issue · 0 comments

redeboer commented

Extend the Visualize solutions notebook with an example that renders only the $J^{PC}$ numbers (spin, parity, $C$ parity; see also #272). It's essentially just an example like the one with the render_mass() converter, but now for render_jpc(). Optionally, one can include $I^G$ (isospin, $G$ parity).

For an example, see the PDG entry for $\pi^0$:
https://pdglive.lbl.gov/Particle.action?init=0&node=S009&home=MXXX005

As a bonus, we can render the transitions with qrules.io.asdot(..., collapse_graphs=True). This requires some minor generalizations to the implementation of the io._dot module.

Implementation sketch

Modified version of render_mass() from Visualize solutions for $J^{PC}$:

from fractions import Fraction


def render_jpc(state: State, digits: int = 3) -> str:
    particle = state.particle
    text = render_fraction(particle.spin)
    if particle.parity is not None:
        text += render_sign(particle.parity)
    if particle.parity is not None:
        text += render_sign(particle.c_parity)
    return text


def render_fraction(value: float) -> str:
    fraction = Fraction(value)
    if fraction.denominator == 1:
        return str(fraction.numerator)
    return f"{fraction.numerator}/{fraction.denominator}"


def render_sign(parity: int) -> str:
    if parity == -1:
        return "⁻"
    if parity == +1:
        return "⁺"
    raise NotImplementedError


jpc_transitions = sorted({
    t.convert(
        state_converter=render_jpc,
        interaction_converter=lambda _: None,
    )
    for t in reaction.transitions
})
dot = qrules.io.asdot(jpc_transitions)
graphviz.Source(dot)

Tasks
Beta Give feedback