Title: Search for dark sector physics and performance of the Belle II detector in final state events with muons and large missing energy
Other Titles: Suche nach Physik des dunklen Sektors in Ereignissen mit Myonen und großer fehlender Energie im Belle II-Detektor
Language: English
Authors: Bertemes, Michel 
Qualification level: Doctoral
Advisor: Schwanda, Christoph 
Assisting Advisor: Inguglia, Gianluca 
Issue Date: 2021
Bertemes, M. (2021). Search for dark sector physics and performance of the Belle II detector in final state events with muons and large missing energy [Dissertation, Technische Universität Wien]. reposiTUm. https://doi.org/10.34726/hss.2021.85804
Number of Pages: 122
Qualification level: Doctoral
This thesis summarizes two different searches for dark sector mediators in final state events consisting of a pair of muons and large missing energy. Both searches are performed using data collected at the Belle II experiment which is located at the SuperKEKB e+e− accelerator in Tsukuba, Japan. A first analysis is looking for the simultaneous production of a dark photon A′ and a dark Higgs h′ in the so-called Dark Higgstrahlung process e+e− → A′h′; A′ → μ+μ− and h′ → invisible. 90% C.L. upper limits on the product of mixing parameter times dark coupling constant εα_D are set in a fully unexplored region, greatly extending the mass range investigated by the KLOE experiment. An other project focuses on the first search for the invisible decay of a Z′ in the process e+ e- → μ+ μ- Z'. This neutral boson belongs to an Abelian symmetry indicated as Lμ − Lτ and may serve as a mediator between the Standard Model and the dark sector. Upper limits will be set at the 90% C.L. on the g′ coupling constant. Finally, the performance of the hardware based low level trigger system of Belle II in identifying the studied low multiplicity events over various sources of background is evaluated.
Keywords: Dunkle Materie; Belle II
Dark matter; Belle II
URI: https://doi.org/10.34726/hss.2021.85804
DOI: 10.34726/hss.2021.85804
Library ID: AC16386560
Organisation: E141 - Atominstitut 
Publication Type: Thesis
Appears in Collections:Thesis

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