Displaced track finding efficiency and detecting new long-lived particles at Belle II

Sumitted to PubDB: 2022-09-20

Category: Master Thesis, Visibility: Public

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Authors	Daniel Marcantonio, Phillip Urquijo
Date	Jan. 1, 2020
Belle II Number	BELLE2-MTHESIS-2022-023
Abstract	There are numerous extensions to the Standard Model that introduce new particles that have long lifetimes, corresponding to a flight length of centimetres or more in a particle collider. No such particle has yet been found, with searches often being limited statistically. The high luminosity that the SuperKEKB collider provides the Belle II experiment allows grants greater statistical power in these searches than ever before, making Belle II the most sensitive experiment to date in detecting new long-lived particles in the mass range of a few Gev/c2. In this thesis, we use Monte Carlo simulations to lay the foundations for a search for long-lived particles. To construct an accurate search , precise understanding of how well the Belle II detector tracks charged particles that originate far from the interaction point is essential. We perform a measurement of displaced track finding efficiency for the first time in the Belle II experiment, using a method involving the partial reconstruction of D∗+ decays. From the result of the tracking study, combined with the outcome of the long-lived particle search we construct, we provide the most accurate estimate of Belle II’s sensitivity to new long-lived particles to date.
Conference	Melbourne