ETD

Archivio digitale delle tesi discusse presso l'Università di Pisa

Tesi etd-11072020-105746


Tipo di tesi
Tesi di laurea magistrale
Autore
CITI, EDOARDO
URN
etd-11072020-105746
Titolo
Precision time-dependent measurements of heavy flavor decays through a new data-driven method for efficiency determination.
Dipartimento
FISICA
Corso di studi
FISICA
Relatori
relatore Punzi, Giovanni
Parole chiave
  • D0 meson
  • charm physics
  • heavy flavour physics
  • CP violation
  • ycp
  • LHCb
  • D0 lifetime
  • efficiency reconstruction
Data inizio appello
07/12/2020
Consultabilità
Tesi non consultabile
Riassunto
The efficiency for track reconstruction provides nowadays the source of the dominating uncertainty over many physical measurments. I focus on the case of the yCP parameter in the decay of the D0 meson, that is a notable example of these issue.
The most precise measurement of yCP made by the LHCb collaboration is: yCP=(0.59 +-0.13(stat) +- 0.09(sys)) %.
The samples of those decays currently available to LHCb are more than 60 times larger now. The reason why a more accurate measure of yCP has not been made yet, in spite of the available data size, is the systematic uncertainty deriving from the knowledge of the efficiency map, which dominates uncertainty of the measurement.
I have explored a new idea for extracting the reconstruction efficiency, based on exploiting the kinematical correlations between the decay products of a decaying particle to extract the efficiency map.
This technique has been first developed on completely general grounds, and then applied to the case of two-body decays of the D0 meson at LHCb. Using the data sample collected by LHCb in Run-2, I have demonstrated that the precision achievable with this method is better that the world average of the D0 lifetime from all previous measurements combined. An important finding has been that the systematic uncertainty associated to my data-driven determination of efficiency is lower than the statistical uncertainty achievable from that same sample.
I applied the method on the LHCb data to perform various precision tests in real-life conditions. Amongst them, I studied the lifetime-difference between the D0->PiPi and D0->KK modes, that is a crucial zero-test for the yCP measurement.
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