Browsing by Subject "Z boson"

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    The effect of hadronization on the φ ∗ distribution of the Z boson in simulation compared to data from the CMS experiment at √ s = 8 TeV
    (2019-08) Lesko, Zachary
    Measurements of the distribution of the Z boson decay are in disagreement with the theoretical distribution. This disagreement is of importance in its relationship to the transverse momentum of the Z boson (QT). This disagreement may be due to the hadronization step of the simulation, which attempts to describe QCD interactions involved in the event. If the hadronizer can be changed to remove this disagreement those changes can be applied to W simulations which would allow for the uncertainty of the W mass measurement to be decreased. This thesis presents normalized results of both measurements and rapidity measurements of the Z boson at a center-of-mass energy of 8 TeV along with multiple simulation results using changes to the hadronizer in an attempt to better match the data. The data used was collected by the CMS detector at the LHC in 2012. This data totaled 19.7 fb􀀀1 of integrated luminosity. Although changes to the hadronizer had a major eect on the simulated results, it was found that none of the changes could fully resolve the disagreement between data and theory.
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    Measurements of Z transverse momentum shape using novel variables with the CMS detector
    (2014-06) Klapoetke, Kevin Humphrey
    The understanding of transverse momentum in a proton-proton collision is important.Particularly at low values, measurements of transverse momentum are not in agreement with proposed models. This thesis describes a measurement of the physics behind the transverse momentum of the Z boson using a method that reduces the effect of energy resolution and capitalizes on the positional accuracy of the CMS detector. This method is a differential cross-section measurement with respect to the presented novel variable,. The data used was from the 2011 run at the LHC experiment, totaling 216pb-1 of integrated luminosity at sqrt(s) = 7TeV.