Understand high background level in HLT1 (e.g. D0 -> K pi)
Following up on #385 (closed), where the observed IP shifts have been understood, but background levels in for example the D0 -> K pi mass distribution are still significantly higher than in HLT2. Can this fully be attributed to missing hadron PID or are other effects playing a role?
Slides 11 and 12 of this presentation show a worse D0 mass resolution for HLT1 compared to HLT2, and a worse impact parameter resolution for the D0 (while the K and pi IP resolutions are comparable between HLT1 and HLT2).