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# System prepended metadata

title: Physics Performance Meeting

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# 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.