337 research outputs found
Measurement of the production cross section of four top quarks in proton-proton collisions at 13 TeV
No full textThe field of particle physics involves not only searches for new particles and measurements of their interactions, but also the design and construction of advanced particle detectors. This thesis presents the measurement of the production cross section of four top quarks in proton-proton collisions at a center-of-mass energy of 13 TeV using 137 fb of integrated luminosity recorded by the CMS experiment at the LHC. This analysis considers events in the final state of a same-sign pair of leptons, notable for being a final state with relatively few Standard Model background events. A boosted decision tree is utilized to discriminate four top quark events from background events. The four top quark production cross section is measured to be fb, consistent with the Standard Model prediction. This measurement is used to constrain the top quark's Yukawa coupling as well as various theories beyond the Standard Model. This thesis also describes the construction and testing of silicon pixel detector modules used in the Phase I upgrade of the CMS pixel detector, and optimization of electron reconstruction methods using the new detector. The role of automated module assembly and quality assurance will be discussed, as well as work towards the construction of a high precision silicon strip detector based telescope
Search for standard model production of four top quarks
No full textThis talk describes efforts towards a first measurement of the standard model production of four top quarks with results based on up to the full Run 2 dataset. It includes implications of this measurement to constrain properties of the Higgs Boson and new physics scenarios including dark matter
COMPUTERIZED WATER DISTRIBUTION MANAGEMENT FOR THE UPPER PAMPANGA RIVER PROJECT, PHILIPPINES
No full textRights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author
Author Correction: A portrait of the Higgs boson by the CMS experiment ten years after the discovery
No full textIn the version of this article initially published, CMS Collaboration author names, affiliations and acknowledgements were omitted and have now been included in the HTML and PDF versions of the articl
Event generator tunes obtained from underlying event and multiparton scattering measurements
No full textNew sets of parameters (“tunes”) for the underlying-event (UE) modelling of the PYTHIA8, PYTHIA6 and HERWIG++ MonteCarlo event generators are constructed using different parton distribution functions. Combined fits to CMS UE proton–proton (pp) data at √s = 7 TeV and to UE proton–antiproton (pp) data from the CDF experiment at lower √s, are used to study the UE models and constrain their parameters, providing thereby improved predictions for proton–proton collisions at 13 TeV. In addition, it is investigated whether the values of the parameters obtained from fits to UE observables are consistent with the values determined from fitting observables sensitive to double-parton scattering processes. Finally, comparisons are presented of the UE tunes to “minimum bias” (MB) events, multijet, and Drell– Yan (qq → Z/γ*→lepton-antilepton+jets) observables at 7 and 8 TeV, as well as predictions for MB and UE observables at 13 TeV
The postmodern sacred: popular culture spirituality in the genres of science fiction, fantasy and fantastic horror
No full textIn my thesis I argue that the return of the religious in contemporary culture has been in two forms the rise of so-called fundamentalisms in the established faiths-Christian, Jewish, Muslim, Hindu, even Buddhist-and the rise of a New Age style spirituality that draws from aspects of those faiths even as it produces something distinctively different. I argue that this shift both produces post-modern media culture, and is itself always-already mediated through the realm of the fictional. Secular and profane are always entangled within one another, a constant and pervasive media presence that modulates the way that contemporary subjects experience themselves and their relationship to the spiritual. I use popular culture as an entry point, an entry point that can presume neither belief nor unbelief in its audiences, showing that it is 'unreal' texts such as Lord of the Rings, Harry Potter, The Matrix and so on that we find religious symbols and ideas refracted through a postmodernist sensibility, with little regard for the demands of 'real world' epistemology.
I argue that it is in this interplay between traditional religions and New Age-ised spirituality in popular culture that the sacred truly finds itself in postmodernity
Measurement of single-diffractive dijet production in proton–proton collisions at √s = 8 TeV with the CMS and TOTEM experiments
No full textMeasurements are presented of the single-diffractive dijet cross section and the diffractive cross section as a function of the proton fractional momentum loss ξ and the four-momentum transfer squared t. Both processes pp → pX and pp → Xp, i.e. with the proton scattering to either side of the interaction point, are measured, where X includes at least two jets; the results of the two processes are averaged. The analyses are based on data collected simultaneously with the CMS and TOTEM detectors at the LHC in proton–proton collisions at √s = 8 TeV during a dedicated run with β∗ = 90m at low instantaneous luminosity and correspond to an integrated luminosity of 37.5nb−1. The single-diffractive dijet cross section σpXjj , in the kinematic region ξ \u3c 0.1, 0.03 \u3c |t| \u3c 1GeV2, with at least two jets with transverse momentum pT \u3e 40 GeV, and pseudorapidity |η| \u3c 4.4, is 21.7 ± 0.9 (stat) +3.0−3.3 (syst) ± 0.9 (lumi) nb. The ratio of the single-diffractive to inclusive dijet yields, normalised per unit of ξ , is presented as a function of x, the longitudinal momentum fraction of the proton carried by the struck parton. The ratio in the kinematic region defined above, for x values in the range −2.9 ≤ log10 x ≤ −1.6, is R = (σpXjj /Δξ)/σjj = 0.025 ± 0.001 (stat) ± 0.003 (syst), where σpXjj and σjj are the single-diffractive and inclusive dijet cross sections, respectively. The results are compared with predictions from models of diffractive and nondiffractive interactions. Monte Carlo predictions based on the HERA diffractive parton distribution functions agree well with the datawhen corrected for the effect of soft rescattering between the spectator partons
Measurement of the differential cross section and charge asymmetry for inclusive pp → W\u3csup\u3e±\u3c/sup\u3e + \u3ci\u3eX\u3c/i\u3e production at √\u3ci\u3es\u3c/i\u3e = 8 TeV
No full textThe differential cross section and charge asymmetry for inclusive pp → W± + X → μ±ν + X production at √s = 8 TeV are measured as a function of muon pseudorapidity. The data sample corresponds to an integrated luminosity of 18.8 fb−1 recorded with the CMS detector at the LHC. These results provide important constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable x from 10−3 to 10−1
Event generator tunes obtained from underlying event and multiparton scattering measurements
No full textNew sets of parameters (“tunes”) for the underlying-event (UE) modelling of the PYTHIA8, PYTHIA6 and HERWIG++ MonteCarlo event generators are constructed using different parton distribution functions. Combined fits to CMS UE proton–proton (pp) data at √s = 7 TeV and to UE proton–antiproton (pp) data from the CDF experiment at lower √s, are used to study the UE models and constrain their parameters, providing thereby improved predictions for proton–proton collisions at 13 TeV. In addition, it is investigated whether the values of the parameters obtained from fits to UE observables are consistent with the values determined from fitting observables sensitive to double-parton scattering processes. Finally, comparisons are presented of the UE tunes to “minimum bias” (MB) events, multijet, and Drell– Yan (qq → Z/γ*→lepton-antilepton+jets) observables at 7 and 8 TeV, as well as predictions for MB and UE observables at 13 TeV
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