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ComPWA / expertsystem

Rule based particle reaction problem solver on a quantum number level
http://expertsystem.rtfd.io
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Implement Particle.__neg__ method #294

Closed redeboer closed 4 years ago

redeboer commented 4 years ago

The implementation in create_anti_particle can be used to check whether one instance of a Particle is the anti-particle of the other. This allows for a more reliable implementation of, say, the C-parity conservation check in conservation_rules (which currently uses PID).

redeboer commented 4 years ago

@spflueger What about implementing a Partilce.__neg__ operator? Then one could just write for instance:

assert pi_minus == -pi_plus

Not sure thought how much sense this syntax makes from a physics point of view. And I'm also not sure how much overhead the construction of a new Particle instance (which __neg__ would do) causes. But maybe dataclasses.replace optimizes that. Nonetheless, a method like is_antiparticle_of or something along those lines would still have to flip several properties, see: https://github.com/ComPWA/expertsystem/blob/61c339457e906b90baa4031539bb103ab7b55d74/expertsystem/data.py#L520-L551

spflueger commented 4 years ago

Sounds quite nice. I think you have to create a new particle anyways, so I would not worry about the overhead. If we want to have a faster comparison check we can always implement that in addition

redeboer commented 4 years ago

There's one problem though: https://github.com/ComPWA/expertsystem/blob/a81dda95e569afa7323cd91578624318d338aba5/expertsystem/data.py#L524-L526 With a __neg__ operator, one cannot set the name of the output particle.