Date on Master's Thesis/Doctoral Dissertation


Document Type

Doctoral Dissertation

Degree Name

Ph. D.


Physics and Astronomy

Degree Program

Physics, PhD

Committee Chair

Banerjee, Swagato

Committee Co-Chair (if applicable)

Davis, Chris

Committee Member

Davis, Chris

Committee Member

Riedel, Thomas

Committee Member

Brown, David

Author's Keywords

Dark matter; Tau; DAQ; PCIe40; KLM; Belle


Dark matter is believed to be a form of matter which seemingly accounts for approximately 85% of the matter in the universe and about 27% of its total mass–energy density. It doesn't participate in electromagnetic interaction, i.e. doesn't interact with light. Consequently, we cannot see it using optical or radio telescope and hence the name dark matter. However, it participates in gravitational interaction, and we hypothesize its existence based on a variety of astrophysical observations, including gravitational effects, that cannot be explained by the accepted theories of gravity unless we account for more matter than can be perceived through electromagnetic interaction. Apart from explaining those observations, the existence of dark matter may also explain the anomalous magnetic moment of muon, violation of lepton flavor universality, or may unlock the path towards supersymmetry. In brief, the existence of dark matter will not only provide us a signature of new physics, but it is also crucial in establishing a scientific understanding of the observed universe. The existence of dark matter can be probed in various ways, one of them is called collider search, where highly energetic particles are smashed together to form unstable and exotic particles. Along with dark matter, new force-carrier particles that interact with dark matter can also be searched for in such experiments. This kind of interaction is known as dark interaction and together with dark matter, they form the dark sector of particles, something beyond the standard model of particle physics. In this thesis, a search for such dark sector candidates that couple with tau lepton is presented, which has been carried out using the collision data at (or near) Y(4S) resonance collected using the improved silicon vertex detector, the so-called SVD2 dataset, from the Belle experiment. The Belle II detector, successor of this Belle detector, is built around the world’s highest luminosity electron-positron collider SuperKEKB, located at the KEK accelerator complex in Japan. In this thesis, a general overview of the SuperKEKB accelerator and the Belle II experiment is also presented. On the technical contribution part, my job as the deputy of operations and slowcontrol developer for the K-long and Muon (KLM) detector is discussed in this thesis. Also, my contribution in the upgrade of various parts of the Data Acquisition (DAQ) system of this experiment is described in detail.