Gutenberg Open Science: Development of Λ baryons reconstruction and its application to the search for a stable hexaquark at Belle II

Please use this identifier to cite or link to this item: http://doi.org/10.25358/openscience-7508

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DC Field	Value	Language
dc.contributor.author	Scavino, Bianca	-
dc.date.accessioned	2022-08-17T11:31:05Z	-
dc.date.available	2022-08-17T11:31:05Z	-
dc.date.issued	2022	-
dc.identifier.uri	https://openscience.ub.uni-mainz.de/handle/20.500.12030/7522	-
dc.description.abstract	QCD-motivated models for hadrons predict a wide variety of exotic hadrons, with structures more complex than the quark-antiquark mesons and the three-quark baryons of the ordinary hadron classification. Among these, one of the most intriguing cases refers to the H dibaryon, an elusive six-quark state with the quark content of two Λ baryons first suggested by R. L. Jaffe in 1977. The search for a stable double strange hexaquark, which, in recent years, was put forward to also be a dark matter candidate, is part of the Belle II physics program. In the coming years, a fraction of the Belle II data taking period will be dedicated to run at the energy of the Υ(3S) resonance. This bb̄ resonance decays primarily via three gluons, in which ss̄ quark pairs are produced with roughly the same probability as uū and dƌ pairs, making it particularly well suited for searches for multiquark states with nonzero strangeness. This thesis describes a feasibility study for the search for a stable double strange six-quark state S produced in Υ(3S) decays, Υ(3S) → SΛΛnπ (with n = 0, 2, 4, 6, and 8). The predictions obtained for the channel with n=0 are compared with an existing result from the BaBar collaboration, while the other channels represent a novel measurement. In order to obtain optimal results, an integral part of the work is the optimization of the Belle II tracking package for displaced vertices with a focus on Λ baryon reconstruction, a key element in the stable hexaquark analysis. After the optimization, the algorithms and selections developed for Λ baryons were extensively tested using Belle II data collected at the Υ(4S) resonance. Finally, a look at the future is taken. Given that the beam background level measured at Belle II in the first data taking periods turned out to be higher than initial estimates, the possible effect of increased background on performance deterioration, both on tracking in general and on the hexaquark analysis in particular, is assessed and discussed in detail. The work presented in this thesis is intended to prepare a measurement where the tools and the analysis procedures developed, as well as the critical points observed, will be used on the Υ(3S) Belle II data to set a new limit on the possible observation of such an exotic state.	en_GB
dc.language.iso	eng	de
dc.rights	InCopyright	*
dc.rights.uri	http://rightsstatements.org/vocab/InC/1.0/	*
dc.subject.ddc	530 Physik	de_DE
dc.subject.ddc	530 Physics	en_GB
dc.title	Development of Λ baryons reconstruction and its application to the search for a stable hexaquark at Belle II	en_GB
dc.type	Dissertation	de
dc.identifier.urn	urn:nbn:de:hebis:77-openscience-ca4525d4-c352-4a51-bf62-ea02b207ed175	-
dc.identifier.doi	http://doi.org/10.25358/openscience-7508	-
jgu.type.dinitype	doctoralThesis	en_GB
jgu.type.version	Original work	de
jgu.type.resource	Text	de
jgu.date.accepted	2022-07-27	-
jgu.description.extent	xiii, 158 Seiten, Diagramme	de
jgu.organisation.department	FB 08 Physik, Mathematik u. Informatik	de
jgu.organisation.number	7940	-
jgu.organisation.name	Johannes Gutenberg-Universität Mainz	-
jgu.rights.accessrights	openAccess	-
jgu.organisation.place	Mainz	-
jgu.subject.ddccode	530	de
jgu.organisation.ror	https://ror.org/023b0x485	-
Appears in collections:	JGU-Publikationen

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