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| Book/Report/Dissertation / PhD Thesis | PUBDB-2017-10993 |
; ;
2017
Verlag Deutsches Elektronen-Synchrotron
Hamburg
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Please use a persistent id in citations: doi:10.3204/PUBDB-2017-10993
Report No.: DESY-THESIS-2017-038
Abstract: This thesis is logically divided into two main parts. The first part present a ZEUS analysis which was performed on the data obtained from electron-proton collisions measured by theZEUS detector for the 2003-2007 running period. The full HERA-II integrated luminosity of376 pb$^{-1}$ is used. The ZEUS detector is sensitive to the full phase space of beauty production,since it has cylindrical geometry, covers a wide rapidity range and was able to measure lowtransverse momentum muons. In this part a measurement of beauty production was studiedvia the process ep $\rightarrow$$e'b{\bar b}X$ $\rightarrow$ $e'\nu{\nu}X$. Making full use of the HERA-II detector upgrade,secondary vertex information was used to constrain the beauty and charm contribution to thisprocess. The result of this analysis is the measurement of the total, visible and differential crosssections for beauty production. The cross sections are compared to next-to-leading order QCDcalculations.Similar to the beauty events, instanton or instanton-induced events involving heavy avourcan also be a source for non-isolated, both like- and unlike-sign muon pairs. In this analysis,instantons were studied with using QCDINS predictions. The data show no indication forinstanton-induced events.The second part is related to CMS tracker alignment. It uses collision and cosmic datasamples obtained by the CMS detector at the Large Hadron Collider in 2012. This part consistsof studies of the CMS tracker alignment weak modes and a detailed study of the \z-rescaling"weak mode. The CMS tracker alignment weak mode study includes the simulation of the weakmodes, and the alignment implementation on top of such simulation. This study shows thatthe alignment procedure of the CMS tracker is stable with regard to the three weak modes:\Twist, Sagitta and Telescope" which stand for three types of systematic shifts of the CMStracker. The \z-rescaling" weak mode shows a strong and unexpected shift of some trackerdetector components in the z direction. To study the issue, a significant number of testssuch as \high level structure" alignment only, alignment with fixed end caps, impact of thepT dependence of the tracks on the alignment procedure, the simulation of cosmic data ascollision data, introducing TID , TEC end cap disk constraints and other important tests wereperformed. Even though this issue was not yet fully solved, the studies performed in this thesisshow consistent and detailed steps that help to better understand the issue and solve it in thefuture.The track helix parametrisation of both the ZEUS and CMS experiments was studied. Achecked, detailed description of such parametrisation as well as its transformation from theCMS format into the ZEUS format is performed. In addition, a CMS physics analyses ofB ! J= K decays was started. These studies were performed with the CMS \open data" forthe 2010 time period. Logically this can be seen as a first step towards a measurement of thetotal beauty cross section in CMS in the same spirit as the one performed with the ZEUS data.
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