Hlt issueshttps://gitlab.cern.ch/lhcb/Hlt/-/issues2021-01-21T19:53:44+01:00https://gitlab.cern.ch/lhcb/Hlt/-/issues/3Bug in BiKalmanFittedElectrons affecting Hlt2LowMultDiElectron CEP line for 2...2021-01-21T19:53:44+01:00Patrick KoppenburgBug in BiKalmanFittedElectrons affecting Hlt2LowMultDiElectron CEP line for 2017-18.This is report of a bug found by @crsanche . As it affects data already taken it cannot be fixed but should still be documented.
CEP J/psi->ee events are triggered by Hlt2LowMultDiElectron https://gitlab.cern.ch/lhcb/Hlt/-/blob/2018-pa...This is report of a bug found by @crsanche . As it affects data already taken it cannot be fixed but should still be documented.
CEP J/psi->ee events are triggered by Hlt2LowMultDiElectron https://gitlab.cern.ch/lhcb/Hlt/-/blob/2018-patches/Hlt/Hlt2Lines/python/Hlt2Lines/LowMult/ElectronLines.py They use BiKalmanFittedElectrons which rely on Brem photons https://gitlab.cern.ch/lhcb/Hlt/-/blob/2018-patches/Hlt/Hlt2SharedParticles/python/Hlt2SharedParticles/TrackFittedBasicParticles.py . If no photons are present in the event the sequence is stopped and no electrons are made, even if one could have electrons with no bremsstrahlung (Check for instance listProperties(tck,'.*/Hlt2LowMultDiElectronFilterSequence') for tck = 0x215517A7). The effect is that on simulated CEP J/psi->ee the efficiency is about 25% for no-bremsstrahlung corrected electrons.
I presume this bug affects all dielectron lines, but the likelihood of having zero photons is negligible for non-CEP data.
cc those involved at the time @johndan @graven @gligorov @rmatev @cofitzpa @apearce @sstahl
For CEP: @bursche @heli @mvesteri @maxime @pgandinihttps://gitlab.cern.ch/lhcb/Hlt/-/issues/2Physics routing bit 46 accepts Hlt1NoBiasEmptyEmpty2018-06-22T17:11:03+02:00Rosen MatevPhysics routing bit 46 accepts Hlt1NoBiasEmptyEmptyThe rate is low so the impact on anything is probably negligible, but this should be fixed.The rate is low so the impact on anything is probably negligible, but this should be fixed.v28r3p1