DC ElementWertSprache
dc.contributor.advisorKasieczka, Gregor-
dc.contributor.advisorSchleper, Peter-
dc.contributor.authorEich, Melanie-
dc.date.accessioned2022-09-26T09:25:39Z-
dc.date.available2022-09-26T09:25:39Z-
dc.date.issued2022-
dc.identifier.urihttps://ediss.sub.uni-hamburg.de/handle/ediss/9809-
dc.description.abstractLong-lived particles are an interesting extension of the standard model of particle physics. This thesis presents a search for such new long-lived particles with lifetimes of the order of a few millimetres produced in Higgs boson decays that then themselves decay into b quark pairs. The long-lived particles are predicted by, for example, Twin Higgs models. These theories solve the so-called little hierarchy problem, increasing the validity of the standard model. The search is performed with proton-proton collisions at a centre-of-mass energy of 13TeV at the LHC corresponding to an integrated luminosity of L = 36.3 fb−1 recorded with the CMS experiment. The search is split into two analyses, depending on the mass of the long-lived particles, because the decay kinematics differ. One analysis is designed for light long-lived particles (m = 15 GeV), and the other analysis is for heavier long-lived particles (m = 40 GeV and m = 55 GeV). The final state of the signal events is expected to contain up to four b quarks. Therefore, events with at least four jets of which at least three have to be b-tagged jets are selected. Two production modes for the signal are investigated: gluon-gluon fusion and vector-boson fusion Higgs boson production modes. Possible signal events are identified by a requirement on the invariant mass of the signal candidate jets. Signal events are further separated from background events using a neural network based jet tagger. The network is parametrised as a function of the masses and lifetimes of the signal prediction. This makes it possible to train the network only once and simultaneously use it for the analyses of different masses and lifetimes. The main background consists of QCD multijet production and is estimated using a data-driven method. Upper limits on the signal strength modifier are calculated at 95% CL as a function of the lifetimes for all investigated masses of the long-lived particles. No evidence for such long-lived particles is observed.en
dc.language.isoende_DE
dc.publisherStaats- und Universitätsbibliothek Hamburg Carl von Ossietzkyde
dc.rightshttp://purl.org/coar/access_right/c_abf2de_DE
dc.subjectlong-liveden
dc.subjectnew physicsen
dc.subjectbeyond standard model searchen
dc.subject.ddc530: Physikde_DE
dc.titleSearch for new long-lived particles with the CMS experiment at √s = 13TeVen
dc.typedoctoralThesisen
dcterms.dateAccepted2022-09-05-
dc.rights.cchttps://creativecommons.org/licenses/by/4.0/de_DE
dc.rights.rshttp://rightsstatements.org/vocab/InC/1.0/-
dc.subject.bcl33.00: Physik: Allgemeinesde_DE
dc.subject.gndLHCde_DE
dc.subject.gndCMSde_DE
dc.type.casraiDissertation-
dc.type.dinidoctoralThesis-
dc.type.driverdoctoralThesis-
dc.type.statusinfo:eu-repo/semantics/publishedVersionde_DE
dc.type.thesisdoctoralThesisde_DE
tuhh.type.opusDissertation-
thesis.grantor.departmentPhysikde_DE
thesis.grantor.placeHamburg-
thesis.grantor.universityOrInstitutionUniversität Hamburgde_DE
dcterms.DCMITypeText-
dc.identifier.urnurn:nbn:de:gbv:18-ediss-103135-
item.advisorGNDKasieczka, Gregor-
item.advisorGNDSchleper, Peter-
item.grantfulltextopen-
item.languageiso639-1other-
item.fulltextWith Fulltext-
item.creatorOrcidEich, Melanie-
item.creatorGNDEich, Melanie-
Enthalten in den Sammlungen:Elektronische Dissertationen und Habilitationen
Dateien zu dieser Ressource:
Datei Prüfsumme GrößeFormat  
Eich_PhDThesis.pdf453ae0e690881cd16b8209dad675e31038.37 MBAdobe PDFÖffnen/Anzeigen
Zur Kurzanzeige

Info

Seitenansichten

199
Letzte Woche
Letzten Monat
geprüft am 28.03.2024

Download(s)

183
Letzte Woche
Letzten Monat
geprüft am 28.03.2024
Werkzeuge

Google ScholarTM

Prüfe