Electron-Positron Experimental Particle Physics

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It is widely believed that the most fundamental constituents of some of the most common elementary particles are quarks, and their anti-matter counterpart, anti-quarks. By probing the existence and structure of these particles, it is possible to learn about the underlying principles governing quark and anti-quark matter. The work in this project will use data collected at the Belle experiment at the High Energy Accelerator Research Organization (KEK) laboratory in Japan to measure the formation of particles known as mesons that consist of a quark-antiquark pair. By studying these mesons, one can probe fundamental physics processes such as Charge Parity (CP) violation, rare meson decays and the existence of possible exotic particles which could indicate the presence of Dark Matter. This effort has a particular focus on the support of students, thereby contributing to the development of a much-needed high tech workforce.Belle is built around the interaction region of an asymmetric electron-positron collider, with electrons having the energy of 8 GeV and positrons having the energy of 3.5 GeV, giving 10.58 GeV center-of-mass energy. The main goal of Belle is to detect mesons made of a quark-anti-quark pair, in particular those mesons made of charm quarks (charmonium) and bottom quarks (bottomonium). The Belle Experiment at KEK in Japan has the world's largest data samples recorded at the bottomonium resonances: upsilon (5S), upsilon (2S) and upsilon (1S). The central aim of this project is to perform very precise measurements of details of fragmentation (the break-up of resonant particles such as the upsilon) and hadronization (the process of initial state quarks and gluons decaying into detectable particles like pions and photons) at a center of mass energy of 10 GeV. This will provide tests of Quantum Chromo-Dynamics (QCD), providing detailed information for theoretical Lattice QCD calculations. The decays of the upsilon(1S) resonance to gluons and photons provides a precise measurement of the QCD strong coupling constant.