Associated Production of W + Charm in 13 TeV Proton-Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton PDF Download

Author: Svenja Karen Pflitsch
Publisher: Springer Nature
ISBN: 303052762X
Category : Science
Languages : en
Pages : 148

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Book Description
The associated production of a W boson and a single charm quark (W+c) is the only process in proton-proton collisions that directly probes the strange quark content of the proton. In this thesis, W+charm production is measured in proton-proton collisions at the LHC at 13 TeV, as recorded by the Compact Muon Solenoid (CMS) experiment. The analysis focuses on the identification of W bosons in their leptonic decay to a muon and a neutrino and charm quarks are tagged via the full reconstruction of D*-Mesons. The measured cross sections of W+c production are used, in combination with other relevant CMS results and the most precise HERA DIS data, in a QCD analysis to determine the strange quark content of the proton. The resulting strange quark distribution and suppression, with respect to the other light sea quarks, are in good agreement with those obtained in neutrino scattering experiments and extend their kinematic reach.

Author: Albert M. Sirunyan
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Sergio Sánchez Navas
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Scientific knowledge experienced an age of explosion during the XX century, fruitful in discoveries that radically changed the perspective we had of Nature. Our current quest is, however, to continue questioning the fundamental aspects of everything that surrounds us, to test until the very end how far the great theories can go, and to pursue with the undeniable task of human restlessness to answer the question “and why is that?”. In the specific topic of this work, we will make use of the largest machine ever built to obtain information about some of the smallest elements of matter, measuring with the best precision up to date the cross section of a process that could shed some light on the mystery of fundamental asymmetry between matter and antimatter in the Universe. Our mind demands symmetry...

Author:
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ISBN:
Category :
Languages : en
Pages : 63

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Measurements are presented of the associated production of a W boson and a charm-quark jet (W + c) in pp collisions at a center-of-mass energy of 7 TeV. The analysis is conducted with a data sample corresponding to a total integrated luminosity of 5 inverse femtobarns, collected by the CMS detector at the LHC. W boson candidates are identified by their decay into a charged lepton (muon or electron) and a neutrino. The W + c measurements are performed for charm-quark jets in the kinematic region $p_T^{jet} \gt$ 25 GeV, $

Author: Luis Pinto Cabrera
Publisher:
ISBN:
Category :
Languages : en
Pages :

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"This thesis presents the measurements of the differential production cross-sections of a Z boson in association with at least one charm-quark-initiated jet, where the Z boson decays leptonically into a muon-antimuon pair. Data recorded in proton-proton collisions by the ATLAS detector at the Large Hadron Collider (LHC) during the years of 2015 to 2018 is utilised, when the LHC was running at a center of mass energy of 13 TeV. The studied data corresponds to a total integrated luminosity of 139 fb^-1. The measurements are compared to simulated data produced at next-to-leading-order and normalized to theoretical predictions at next-to-next-leading order. The results show that predictions underestimate the total number of events by 50% but display a good modelling of all distribution shapes of the chosen observables in data. The discrepancy can be attributed to a problem in the normalisation but further studies need to be made to settle the issue"--

Author:
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Languages : en
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A search for the production of a single top quark in association with a Z boson is presented, both to identify the expected standard model process and to search for flavour-changing neutral current interactions. The data sample corresponds to an integrated luminosity of 19.7 inverse-femtobarns recorded by the CMS experiment at the LHC in proton-proton collisions at $\sqrt{s}$ = 8 TeV. Final states with three leptons (electrons or muons) and at least one jet are investigated. An events yield compatible with tZq standard model production is observed, and the corresponding cross section is measured to be sigma(p p -> t Z q -> l nu b l+ l- q) = 10 +8/-7 fb with a significance of 2.4 standard deviations. No presence of flavour-changing neutral current production of tZq is observed. Exclusion limits at 95% confidence level on the branching fractions of a top quark decaying to a Z boson and an up or a charm quark are found to be B(t -> Z u) 0.022% and B(t - Z c)

Author: Toni Mäkelä
Publisher: Springer Nature
ISBN: 3031297792
Category : Science
Languages : en
Pages : 173

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Book Description
This book presents the first global interpretation of measurements of jet and top quark production at the Large Hadron Collider, including a simultaneous extraction of the standard model parameters together with constraints on new physics, unbiased from the assumptions on the standard model parameters. As a long-standing problem, any hadron collider search for new physics depends on parton distribution functions, which cannot be predicted but are extracted experimentally. However, performing the extraction in the same kinematic region where physics beyond the standard model is expected to manifest causes the risk of absorbing the new physics effects into the parton distributions. In this book, the issue is addressed by extending the standard model by effective contributions from quark contact interactions describing new physics and extracting the parton distributions and standard model parameters simultaneously with setting limits on the contact interactions. In the process, the most precise single measurement of the strong coupling constant at the LHC is performed, to date. Furthermore, the book details the first investigation of the mass renormalization scale dependence of the top quark mass, highlighting the importance of a proper scale choice for obtaining robust predictions and improving the precision of experimental analyses. The initial chapters provide the reader with a succinct yet accessible introduction to the relevant theoretical and experimental topics. The presented investigations are at the edge of precision in the phenomenology of high-energy physics and serve to pave the road toward a global interpretation of LHC data.

Author:
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Category :
Languages : en
Pages : 7

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The authors present the first measurement of the production cross section of a W boson with a single charm quark (c) in p{bar p} collisions at √s = 1.96 TeV, using soft muon tagging of c jets. In a data sample of ≈ 1.8 fb−1, recorded with the CDF II detector at the Fermilab Tevatron, they select events with W + 1 or 2 jets. They use the charge correlation between the W and the muon from the semileptonic decay of a charm hadron to extract the We signal. They measure [sigma]{sub Wc} (p{sub Tc} > 20 GeV/c,

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 7

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Book Description
The authors present the first measurement of the production cross section of a W boson with a single charm quark (c) in p{bar p} collisions at √s = 1.96 TeV, using soft muon tagging of c jets. In a data sample of ≈ 1.8 fb−1, recorded with the CDF II detector at the Fermilab Tevatron, they select events with W + 1 or 2 jets. They use the charge correlation between the W and the muon from the semileptonic decay of a charm hadron to extract the We signal. They measure?{sub Wc} (p{sub Tc}> 20 GeV/c,

Author: Matthias U. Mozer
Publisher: Springer
ISBN: 3319303813
Category : Science
Languages : en
Pages : 121

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Book Description
The book discusses the recent experimental results obtained at the LHC that involve electroweak bosons. The results are placed into an appropriate theoretical and historical context. The work pays special attention to the rising subject of hadronically decaying bosons with high boosts, documenting the state-of-the-art identification techniques and highlighting typical results. The text is not limited to electroweak physics in the strict sense, but also discusses the use of electroweak vector-bosons as tool in the study of other subjects in particle physics, such as determinations of the proton structure or the search for new exotic particles. The book is particularly well suited for graduate students, starting their thesis work on topics that involve electroweak bosons, as the book provides a comprehensive description of phenomena observable at current accelerators as well as a summary of the most relevant experimental techniques.