Fix for Loopers identified as primaries#15603
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sawenzel
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Jul 16, 2026
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Looks correct to me. Maybe as a follow-up we could use a more dedicated encoding (e.g. the gen field) so we don't confuse the loopers' status 2 with genuinely decayed particles?
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As reported in https://its.cern.ch/jira/browse/O2-7039, the loopers are identified as physical primaries as they check all the boxes in the isPhysicalPrimary function definition.
By setting the HepMC status to a number != 1 the particle is automatically reported as non-primary, while the transport is insured with the kToBeDone flag, which doesn't depend anymore on the HepMC status. Potentially we could set an entirely different code than 2 to always be able to identify loopers, however I'm not sure how the generators handle that code (as it is set usually from the status code of the generated particle as of now in O2)