000002844 001__ 2844
000002844 005__ 20220202170147.0
000002844 037__ $$aBELLE2-MTHESIS-2022-002
000002844 041__ $$afre
000002844 100__ $$aAlizée Brouillard
000002844 245__ $$aTrouver le méson B d’origine à l’aide d’un réseau de neurones à graphes à Belle II
000002844 260__ $$aStrasbourg$$bUniversité de Strasbourg$$c2021
000002844 300__ $$a66
000002844 500__ $$aPresented on 08 09 2021
000002844 502__ $$aMSc$$bStrasbourg, Université de Strasbourg$$c2021
000002844 520__ $$aTo find new physics beyond Standard Model, the Belle II experiment performs precision measurements to bring to light deviations between theory and experimental data. SuperKEKB collider, located in Tsukuba in Japan, collides electron and positron beams with the energies 7 GeV and 4 GeV. The annihilation of an electron and a positron produces the Υ(4S) resonance which decays to a pair of charged mesons B+B− or neural mesons B0B0. These mesons decay to intermediate particles, and so on, up to the so-called final state particles. The purpose of this end-of-course internship is to implement an algorithm which assigns each particle to its native B meson, with the matrix of relations. We implemented a graph neural network with the library PyTorch of Python because we work with fully connected graph and disintegration tree, which are structured data. We showed the efficiency of our algorithm working on disintegration modelled by the phasespace library. Each disintegration is a topology. We gradually increased the complexity of the data and highlighted the factors which affect the most the efficiency. We compared the performances obtained with the neural graph network and the Thrust method, which is traditionally used to solve this problem. This end-of-course internship for the Telecom Physique Strasbourg engineering degree took place at the Institut Pluridisciplinaire Hubert-Curien in Strasbourg. This work was conducted between March first 2021 and July 16th 2021.
000002844 700__ $$aGiulio Dujany$$edir.
000002844 8560_ $$fgiulio.dujany@iphc.cnrs.fr
000002844 8564_ $$uhttps://docs.belle2.org/record/2844/files/BELLE2-MTHESIS-2022-002.pdf
000002844 980__ $$aTHESIS