Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
HK: Fachverband Physik der Hadronen und Kerne
HK 19: Heavy-Ion Collisions and QCD Phases IV
HK 19.5: Vortrag
Dienstag, 11. März 2025, 16:45–17:00, HS 3 Chemie
XGboost based direct photon and neutral meson analysis for ALICE Pb−Pb collision at √sNN = 5.02 TeV — •Abhishek Nath for the ALICE Germany collaboration — Ruprecht Karl University of Heidelberg, Germany
Direct photons act as a unique probe to characterize heavy-ion collision as they are color-blind and do not interact strongly with the medium once formed. Furthermore, being produced at all stages of collision, they are perfect to characterize the space-time evolution of the QCD medium. However, due to decays of neutral mesons (mostly π0 and η) to γ, a large amount of background exists for such signals. This demands a precise measurement of the background since direct and decay photons are indistinguishable in a detector.
The current run 2 direct photons studies utilizing the Photon Conversion Method (PCM) are associated with large uncertainties specifically in pT < 2 GeV making the final direct photon yield less significant. This talk presents the use of classical machine learning models namely XGBoost with PCM to address the problem. We use the models to increase the photon sample’s purity and efficiency. This is followed by measuring the neutral mesons via their strongest γ decay channel and finally obtaining direct photon measurement. A comparison between standard cut-based analysis and ML-induced analysis for both photons and neutral meson is conducted to assess the impact of the ML models on the significance of measurement
Keywords: ALICE; Photon conversion; PbPb collision; direct photons; neutral mesons