# Physics Performance Meeting Slides: https://indico.belle2.org/event/4416/ ## Alignment for lifetime measurements (Angelo Di Canto) * Goal: Competitive D0 and D+/- lifetime measusurements * Alignment is the largest systematic uncertainty for D->Kpi * systematics from day-to-day difference in real data, and simulated alignment weak modes (added in quadrature) * limited MC statistics requires correction for different true decay time of the truth-matched sample to avoid double counting statistical uncertainties #### Questions * Petar: Can a similar procedure be followed by other groups, like for the tau lifetime? * Yes. Ideally with larger centrally produced samples. * Karim: page 6, why are the alignment effects so different for different D decay modes? * Probably residual effects of our limited samples for the different D0 modes. The D0 vs D+ difference should scale with the lifetime ratio (and it does). * Karim: How do the backgrounds contribute to the systematic uncertainties? * It scales with the fraction of backgrounds for the D0 (4x larger for D0->K3pi). For D+, the systematic is due to the background modeling. We have been conservative to cover for observed data-MC differences, likely due to imprefections in the MC decay tables . ## Neutrals (Savino Longo) * release-05/MC14 vs latest buckets: waiting for grid jobs to finish, but we will discuss latest results in the next neutrals meeting (https://indico.belle2.org/event/4552/) ## Tracking (Petar Rados) * Traditionally will hold a "long" tracking meeting in the week before the B2GM ## Hadron ID (Angelo Di Canto) * bucket 18 data studies in systematics framework ongoing * charge dependent efficiency differences can introduce asymmetries, corrections will be provided for different charges. The asymmetries are smaller and data/MC better than for Moriond (mostly due to a better CDC calibration), but they are still at the percent level. Source is not understood yet. ## AOB * Giulia: release-06 will include trigger jitter. Will inform librarians to validate the effect of the jitter **before** the release feature freeze end of June.