Dissertations / Theses: 'Triple Gauge Boson Couplings'

1

Lloyd, Alun Wyn. "A measurement of triple gauge boson couplings in fully leptonic W decays." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369082.

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Uchida, Yoshi 1971. "Observations and measurement of W boson production and triple gauge couplings at LEP II." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8279.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2001.
Includes bibliographical references (leaves 48-52).
W-Pair and Single-W production events are observed at LEP, the Large Electron Positron collider at CERN, using the L3 detector. All decay channels are considered, and data taken in the years 1998 and 1999, with electron-positron collision centre-of-mass energies from 189 GeV to 202 GeV are analysed. The integrated luminosity of the analysed data corresponds to approximately 400pb-1, and a total of approximately 5000 W-pair events and 100 single-W events are selected. The observed cross sections of these W production processes and the differential distributions of the event shapes are then used to measure the couplings of Wbosons with Z bosons and photons. Emphasis is placed on the unambiguous and efficient combination of the information from the different production and decay channels. For the couplings in the model in which gauge invariance is realised linearly, the following results are obtained ... where the errors shown are statistical, systematic and theoretical respectively. All results show consistency with expectations from the Standard Model.
by Yoshiyuki Uchida.
Ph.D.

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Verzocchi, Marco. "Measurement of Single W Production and Triple Gauge Boson Couplings in e+ e- Collisions at sqrt(s) = 161 - 189 GeV." Freiburg i. Br. : Universität, 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8486389.

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Fischer, Julia [Verfasser]. "Measurement of electroweak W + Jets Production and Search for anomalous Triple Gauge Boson Couplings with the ATLAS Experiment at √ s = 8TeV / Julia Fischer." Wuppertal : Universitätsbibliothek Wuppertal, 2016. http://d-nb.info/112033781X/34.

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5

Madsen, Paul E. (Paul Edward) Carleton University Dissertation Physics. "Probing anomalous contributions to triple boson couplings." Ottawa, 1994.

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6

Tobin, Mark. "A measurement of triple gauge couplings with DELPHI at LEP2." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250480.

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7

Li, Shu. "Mesure de la production W+W− dans les collisions proton-proton à $\sqrt{s} = 7 TeV avec le détecteur ATLAS au LHC." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4107.

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Cette thèse présente le mesure des sections efficaces de production WW MS et la détermination des couplages triples (TGCs) correspondants en utilisant ces 4.7 fb⁻¹ de donnes 2011 de collision pp. Ces mesures permettent un test contraignant du secteur 'électrofaible non abélien SU(2) X U(1) du Modèle Standard; donnent l'opportunité de sonder la nouvelle physique `a travers les couplages triples anormaux de bosons de jauge (aTGCs) qui seront observés dans la distribution des variables cinématiques des WW produits ou de leurs produits de désintégration finaux dans le secteur de haute 'énergie; et permettent d'avoir une bonne compréhension du bruit de fond irréductible dans la recherche du boson de Higgs dans le canal de d'esint'egration H → W⁺W⁻.Ce travail de th`ese donne un base solide pour les mesures à venir de la production WW avec les ∼25 fb⁻¹ de luminosité intègré de donnes a 8 TeV prévue pour la fin 2012, qui conduiront vers une amélioration de la précision et des limites plus strictes sur les aTGCs
This thesis presents a measurement of the SM WW production cross section and the determination of the corresponding limits on anomalous triple gauge boson couplings (aTGCs), using the 2011 4.7 fb⁻¹ pp collisions data at 7 TeV collected in 2011. The measurement allows for a stringent test of the non-Abelian SU(2) X U(1) SM electroweak sector and probes new physics that could manifest itself through aTGCs that may alter the observed production cross section or kinematic distributions. This measurement also provides a good understanding of the irreducible background in searches for the Higgs boson through the H → W⁺W⁻ decay channel.This thesis work has laid a solid foundation for further measurements of the WW production with the ∼25 fb⁻¹ integrated luminosity 8 TeV recorded data expected by the end of 2012, which will further improve the precision and yield more stringent limits on the aTGCs

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Rosten, Jonatan Hans Niclas. "The ZZ → 4l process and anomalous triple gauge couplings with ATLAS at the LHC." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/271838.

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This thesis is a presentation of an analysis of the $ZZ\rightarrow 4\ell$ ($\ell = e,\mu$) process in proton-proton collisions with centre-of-mass energy $\sqrt{s}$ = 13 TeV at the LHC during 2015 and 2016 (a total integrated luminosity of 36.1 fb$^{-1}$), using the ATLAS detector. Candidate $ZZ \rightarrow 4\ell$ events are selected in the three decay channels, $4e$, $2e2\mu$ and $4\mu$. The cross section of the $ZZ\rightarrow 4\ell$ process is measured in four fiducial regions closely matching the detector acceptance: one for each decay channel ($4e$, $2e2\mu$ and $4\mu$) and one for the combination of all decay channels. The total cross section of $pp\rightarrow ZZ$ is measured in a phase-space in which both $Z$ bosons have a mass $m_{Z}$ in the range 66 GeV $ < m_{Z} < $ 116 GeV to be 16.5 $\pm 0.5$ (stat.) $\pm 0.4$ (syst.) $\pm 0.5$ (lumi.)$\,$ pb which is consistent with a next-to-next-to-leading-order prediction of $16.9^{+0.6}_{-0.5}$ pb. Observed event yields in four bins of transverse momentum are used to set 95{\%} CL$_{\text{s}}$ limits on four neutral triple gauge couplings ($f^{V}_{i}$, $V=Z,\gamma$, $i=4,5$) which parameterise an effective $ZZV$ vertex (assuming both $Z$ bosons are on shell). The obtained limits are of the order of $|f^{V}_{i}|<0.0017$.

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Buttinger, William Christopher Jan. "ZZ production and limits on anomalous triple gauge couplings with the ATLAS experiment at the LHC." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648681.

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10

Sekaric, Jadranka. "Studies of gauge boson production with a gamma-gamma collider at TESLA." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2006. http://dx.doi.org/10.18452/15508.

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Ohne ein Standard Modell Higgs werden Wechselwirkungen zwischen Eichbosonen stark bei hohen Energien. Jeder tri- und quadrilinare Eichboson-Vertex ist charakterisiert durch einen Satz von Kopplungen der schon bei niedrigeren Energien als der Skala für neue Physik von seiner Standardmodell- Erwartung abweichen sollte. Die genaue Messung der Eichbosonkopplungen gewährt daher Einblicke in den Mechanismus der elektroschwachen Symmetriebrechung und anomale Werte signalisieren neue Physik. Die Sensitivität der Messung der geladenen Eichboson Kopplungen an einem Photoncollider mit TESLA Parametern wurde studiert. Die betrachteten Prozesse sind ein- und zwei-W-Boson Produktion in Elektron-Photon und Photon-Photon Kollisionen bei einer Elektron-Elektron Energie von 500 GeV. Signal und Untergrund Ereignisse wurden im hadronischen Zerfallskanal analysiert und ein Satz von konsekutiven Schnitten wurde angewandt, die eine gute Effizienz und Reinheit des Signals ergaben. Die selektierten Ereignisse wurden durch kinematische Variablen beschrieben, die sensitiv sind auf anomale Kopplungen. Eine neue Methode wurde angewandt, um dies Winkelverteilungen in Anwesenheit von anomalen Kopplungen zu fitten. Dazu wurden die differentiellen Wirkungsquerschnitte in bis zu quadratischen Thermen in den Kopplungen entwickelt. Im Fit wurde diese Funktion benutzt, um die mehrdimensional gebinnten Verteilungen abhängig von den anomalen Kopplungen zu rewichten. Dabei wurde auch die Unsicherheit in der Normalisierung berücksichtigt. Außerdem wurden einige Quellen systematischer Fehler, z.B. durch die Strahlenergie, die W-Boson Masse und die Polarisationsmessung untersucht. Die erwarteten Fehler auf die Eichkopplungen bei einem Photon-Collider sind ca. zwei Größenordnungen kleiner als bei LEP und am Tevatron, so dass ein sehr präziser Test von Physik jenseits des Standardmodells möglich wird. Die Optimierung der Vorwärtsregion der Detektors reduziert den nieder- energetischen Untergrund auf ein tolerierbares Maß. Dies schafft die nötige saubere Umgebung für eine präzise Messung der Eichkopplungen.
In absence of the Standard Model (SM) Higgs boson the interaction among the gauge bosons becomes strong at high energies and influences the couplings between them. Each trilinear and quartic gauge boson vertex is characterised by a set of couplings which are expected to deviate from their SM values already at energies lower than the energy scale of the New Physics (NP). The precise measurement of gauge boson couplings can provide clues to the mechanism of the electroweak symmetry breaking and their anomalous values can be a sign of a NP effect beyond the SM. The sensitivity estimation of the measurement of charged trilinear gauge couplings (TGCs) at the Photon Collider based on TESLA parameters has been studied. The considered interactions are the single and double W boson production in electron-photon and photon-photon collisions (signals) at electron-electron centre-of-mass energy of 500 GeV. Signal and background events in the hadronic decay mode overlayed with the pileup, are simulated and analysed and a set of consecutive cuts is applied resulting in good signal efficiencies. The selected events are described with kinematical variables sensitive to TGCs. A new method has been applied to fit event angular distributions in the presence of anomalous TGCs expanding the dependence of the differential cross-section up to quadratic term in the TGCs. In the fit this expression is used to reweight the SM multi-dimensional binned distributions dependent on TGCs where also the uncertainty on the total normalisation is taken into account. Some sources of systematic errors are considered, as the beam energy, the W boson mass and the polarisation measurement. The estimated precisions of the TGC measurements at a photon collider are about one to two orders of magnitude higher than at LEP and Tevatron providing a measurement highly sensitive to the physics beyond the Standard Model. The optimisation of the forward region of the detector brings the amount of the low-energy background to the manageable level providing a clean environment for the TGC measurements at a photon collider with estimated precisions.

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11

Mengarelli, Alberto <1981&gt. "Measurement of the ZZ production cross section and limits on anomalous neutral triple gauge couplings with ATLAS." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5196/1/Mengarelli_Alberto.pdf.

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The main work of this thesis concerns the measurement of the production cross section using LHC 2011 data collected at a center-of-mass energy equal to 7 TeV by the ATLAS detector and resulting in a total integrated luminosity of 4.6 inverse fb. The ZZ total cross section is finally compared with the NLO prediction calculated with modern Monte Carlo generators. In addition, the three differential distributions (∆φ(l,l), ZpT and M4l) are shown unfolded back to the underlying distributions using a Bayesian iterative algorithm. Finally, the transverse momentum of the leading Z is used to provide limits on anoumalus triple gauge couplings forbidden in the Standard Model.

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Mengarelli, Alberto <1981&gt. "Measurement of the ZZ production cross section and limits on anomalous neutral triple gauge couplings with ATLAS." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5196/.

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The main work of this thesis concerns the measurement of the production cross section using LHC 2011 data collected at a center-of-mass energy equal to 7 TeV by the ATLAS detector and resulting in a total integrated luminosity of 4.6 inverse fb. The ZZ total cross section is finally compared with the NLO prediction calculated with modern Monte Carlo generators. In addition, the three differential distributions (∆φ(l,l), ZpT and M4l) are shown unfolded back to the underlying distributions using a Bayesian iterative algorithm. Finally, the transverse momentum of the leading Z is used to provide limits on anoumalus triple gauge couplings forbidden in the Standard Model.

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13

Bell, Paul James. "Constraints on anomalous quartic gauge boson couplings at OPAL and the system test of the ATLAS barrel SCT." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416709.

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14

Edwards, Nicholas Charles. "Measurement of the ZZ production cross section and limits on anomalous neutral triple gauge couplings with the ATLAS detector." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4478/.

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This thesis presents measurements of the ZZ production cross section in proton-proton collisions at √s = 7 TeV and at √s = 8 TeV, using data recorded by the ATLAS experiment at the LHC in 2011 and 2012. Events are selected which are consistent with two Z bosons decaying to electrons or muons. The cross section is first measured in a fiducial phase-space corresponding closely to the detector acceptance. For the 7 TeV measurement, this phase-space is defined by requiring four electrons or muons with pT > 7 GeV and |eta|<3.16, with a minimum separation between any pair of leptons (electrons or muons) of delta(R)=0.2. The leptons must form two opposite-sign same-flavour pairs, each with invariant mass 66 < m(ll) < 116 GeV. The fiducial cross section times branching ratio to four electrons or muons measured in a dataset corresponding to an integrated luminosity of 4.6 fb−1 is 25.2 +3.3 −3.0 (stat) +1.2 −1.0 (syst) +1.1 −0.9 (lumi) fb. For the 8 TeV measurement, the fiducial phase-space is defined in the same way, except with the lepton pseudo-rapidity requirement tightened to |eta| < 2.7. The fiducial cross section measured in a dataset corresponding to an integrated luminosity of 20 fb−1 is 20.8 +1.3 -1.2 (stat) +1.0 -0.9 (syst) +0.6 -0.6(lumi) fb. Additionally, a fiducial cross section allowing one of the Z bosons to be off shell is measured at √s = 7 TeV by relaxing the mass requirement on one of the lepton pairs to ml−l+ > 20 GeV. This is found to be 27.8 +3.6 -3.4 (stat) +1.8 -1.6 (syst) +1.1 -1.0 (lumi) fb. These results are then used to derive the total cross section for ZZ production with Z bosons in the mass range 66 GeV to 116 GeV, by correcting for the acceptance of the fiducial phase-space and the Z -> ll branching fractions. The total cross section is measured to be 7.0 +0.9 -0.8 (stat) +0.4 -0.3 (syst) +0.3 -0.2 (lumi) pb at √s = 7 TeV and − 7.1 +0.4 -0.4 (stat) +0.4 -0.3 (syst) +0.2 -0.2 (lumi) pb at √s = 8 TeV, which is consistent with the Standard Model expectation of 5.9 +/- 0.2 pb at √s = 7 TeV and 7.2 +/- 0.2 pb at √s = 8 TeV, calculated to next-to-leading order in QCD. The differential cross section in bins of three kinematic variables is also presented. The differential event yield as a function of the transverse momentum of the highest transverse momentum Z boson is used to set limits on the strength of anomalous ZZZ and ZZgamma neutral triple gauge boson couplings, which are forbidden in the Standard Model. The limits obtained with the √s = 8 TeV data are the most constraining to date.

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Machin, D. "The global calorimeter trigger for CMS and a study of sensitivity limits in neural triple gauge boson vertices." Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419681.

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16

Jeanty, Laura Elizabeth. "Measurement of the WZ Production Cross Section in Proton-Proton Collision at $\sqrt s = 7 TeV$ and Limits on Anomalous Triple Gauge Couplings with the ATLAS Detector." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11023.

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In this dissertation, we present a study of WZ production in proton-proton collisions at a center-of-mass energy of 7 TeV. The data analyzed was collected by the ATLAS detector and corresponds to an integrated luminosity of $4.6 fb^{−1}$ provided by the Large Hadron Collider in 2011. We select WZ events in the fully leptonic decay mode with electrons, muons, and missing transverse energy in the final state. Events are required to have three isolated leptons with significant transverse momentum, a large missing transverse energy, a Z candidate reconstructed from two of the selected leptons, and a W candidate reconstructed from the missing transverse energy and third lepton. The major backgrounds to the WZ signal in the leptonic decay channel are Z+jets events, ZZ production, Z+photon events, and events with top quarks. We estimate the Z+jets and top quark background contributions from data and take the expected contribution for the other background processes from simulation. We observe 317 WZ candidates in data, with a background expectation of $68\pm10$ events. The total production cross section is extracted from the selected sample using a maximum likelihood method and is determined to be $19.0^{+1.4}_{-1.3} (stat) \pm0.9 (syst) \pm0.4 (lumi) pb$, which is consistent with the next-to-leading Standard Model prediction of $17.6^{+1.1}_{-1.0} pb$. WZ production in the Standard Model includes a contribution from the WWZ triple gauge boson vertex. If new physics beyond the Standard Model exists and interacts with W and Z bosons, the coupling of the WWZ vertex could differ from the Standard Model prediction. We set limits on anomalous triple gauge boson couplings using the transverse momentum spectrum of Z bosons in the selected sample. We derive the 95% confidence interval for three model-independent anomalous triple gauge couplings using a frequentist approach and set the most stringent bounds to date on two of the three parameters.
Physics

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17

Shrestha, Shruti. "A measurement of Z(vv̄)[photon] cross section and limits on anomalous triple gauge couplings at [square root of]s = 7 TeV using CMS." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/15316.

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Doctor of Philosophy
Department of Physics
Yurii Maravin
In this thesis, the first measurement of Z(vv̄)[photon] cross section in pp collisions at [square root of]s = 7 TeV has been done using data collected by the CMS detector. The measured cross section is 21.3 ± 4.2 (stat.) ± 4.3 (syst.) ± 0.5 (lumi.) fb. This measurement is based on the observations of events with missing transverse energy in excess of 130 GeV and photon in the rapidity range [eta] < 1.44 of transverse momentum in excess of 145 GeV in a data sample corresponding to an integrated luminosity of 5 fb⁻¹. This measured cross section is in good agreement with the theoretical prediction of 21.9 ± 1.1 fb from BAUR. Further, neutral triple gauge couplings involving Z bosons and photons have been studied. No evidence for the presence of such couplings is observed and is in agreement with the predictions of the standard model. We set the most stringent limits to date on these triple gauge couplings.

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Moreno-Lopez, Deywis [Verfasser]. "Measurement of the ZZ production cross section and limits to the anomalous triple gauge couplings with forward electrons with the ATLAS detector / Deywis Moreno-Lopez." Mainz : Universitätsbibliothek Mainz, 2015. http://d-nb.info/1070829056/34.

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19

Kagan, Michael Aaron. "Measurement of the $W^{\pm}Z$ Production Cross Section and Limits on Anomalous Triple Gauge Couplings at $\sqrt s = 7 TeV$ using the ATLAS detector." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10380.

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This dissertation presents a measurement of the $W^{\pm}Z$ production cross section and limits on anomalous triple gauge couplings in proton-proton collisions at a center of mass energy of 7 TeV using data produced by LHC collisions and acquired by the ATLAS detector in 2011. The measurement and limits probe the electroweak sector of the Standard Model at high energies and allow for generic tests for new physics that could be present at high energy scales. This analysis is also useful for understanding the ATLAS detector response in the presence of multi-lepton signatures. The dataset used corresponds to an integrated luminosity of $1.02 fb^{−1}$. The measurement relies on the leptonic decay modes of the W and Z, resulting in final states with electrons, muons, and missing energy. Events are selected by requiring three high momentum leptons, a large missing transverse energy, a Z candidate (reconstructed from two of the leptons) with a mass consistent with the Z pole mass, and a W candidate (reconstructed from the third lepton and the missing energy) with a large transverse mass. The backgrounds to the $W^{\pm}Z$ process are estimated using Monte Carlo simulations and Data-Driven techniques. A total of 71 $W^{\pm}Z$ candidate events are observed in data, with 50.3 signal and 12.1 background events expected. The production cross section is extracted from these events using a maximum likelihood method, and is found to be in good agreement with the Standard Model expectation. Limits at the 95% confidence interval on anomalous triple gauge couplings are extracted from the observed event yields using a frequentist limit setting approach.
Physics

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20

Gumpert, Christian. "Measurement of Electroweak Gauge Boson Scattering in the Channel pp → W ± W ± jj with the ATLAS Detector at the Large Hadron Collider." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-162847.

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Particle physics deals with the elementary constituents of our universe and their interactions. The electroweak symmetry breaking mechanism in the Standard Model of Particle Physics is of paramount importance and it plays a central role in the physics programmes of current high-energy physics experiments at the Large Hadron Collider. The study of scattering processes of massive electroweak gauge bosons provides an approach complementary to the precise measurement of the properties of the recently discovered Higgs boson. Owing to the unprecedented energies achieved in proton-proton collisions at the Large Hadron Collider and the large amount of data collected, experimental studies of these processes become feasible for the first time. Especially the scattering of two W± bosons of identical electric charge is considered a promising process for an initial study due to its distinct experimental signature. In the course of this work, 20.3 fb−1 of proton-proton collision data recorded by the ATLAS detector at a centre-of-mass energy of √s = 8 TeV are analysed. An analysis of the production of two W± bosons of identical electric charge in association with two jets, pp → W ± W ± jj, is conducted in the leptonic decay channel of the W± bosons. Thereby, emphasis is put on the development of methods for the estimation of experimental backgrounds as well as on the optimisation of the event selection. As a result of this work, first experimental evidence for the existence of the aforementioned process is established with an observed significance of 4.9. Based on the number of observed events in the selected phase space the extracted fiducial cross section is σ(fid) = (2.3 ± 0.5(stat.) +0.4/−0.3 (sys.)) fb which is in agreement with the prediction of the Standard Model of σ(fid,SM) = (1.6 ± 0.2) fb. Of particular theoretical interest are electroweak contributions to the pp → W ± W ± jj process due to their sensitivity to the nature of the electroweak symmetry breaking mechanism. Criteria for a dedicated event selection are investigated and implemented in the analysis with the goal of enhancing the sensitivity to these contributions. First experimental evidence for the presence of electroweak contributions to the pp → W ± W ± jj process can be claimed with an observed significance of 4.1. The cross section extracted in the selected phase space region is found to be σ(fid) = (1.7 +0.5/−0.4 (stat.) ± 0.3(sys.)) fb which is 1.3 standard deviations above the theoretical prediction of the Standard Model of σ(fid,SM) = (1.0 ± 0.1) fb. A variety of extensions to the Standard Model predict modifications to the electroweak gauge sector. In the context of the electroweak chiral Lagrangian, which serves as an effective approximation of these theories in the energy regime E = 1 − 3 TeV, anomalous contributions to the quartic WWWW gauge coupling can be described by the parameters α4 and α5 . The selection of events is optimised again to enhance the sensitivity to these two parameters. On the basis of the number of events observed in this phase space region, the following one-dimensional confidence intervals at the 95% confidence level are derived: −0.09 ≤ α4 ≤ 0.10 and −0.15 ≤ α5 ≤ 0.15. At present, these limits represent the most stringent constraints on contributions from new physics processes to the quartic WWWW gauge coupling.

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21

Kaneti, Steven. "A measurement of the ZZ --> l⁻l⁺ vv̄ cross section at 8 TeV and limits on anomalous neutral triple gauge couplings with the ATLAS detector." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709405.

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22

Becker, Maurice [Verfasser]. "Measurement of ZZ production and search for anomalous neutral triple gauge couplings in pp collisions at [square root]s = 13 TeV with the ATLAS experiment / Maurice Becker." Mainz : Universitätsbibliothek Mainz, 2018. http://d-nb.info/116591400X/34.

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23

Dobbs, Matthew. "Probing the Three Gauge-boson Couplings in 14 TeV Proton-Proton Collisions." Thesis, 2002. http://hdl.handle.net/1828/4581.

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The potential for probing the Standard Model of elementary particle physics by measuring the interactions of W -bosons with Z0-bosons and photons (WW and WWZ triple gauge-boson couplings) using TeV-scale proton-proton collisions is described in the context of the ATLAS detector at the 14 TeV Large Hadron Collider (LHC). The ATLAS detector and LHC are currently under construction at the European Organization for Nuclear Research (CERN), with the rst data expected in 2006. New analysis techniques are presented in this thesis: (1) A new strategy for placing limits on the consistency of measured anomalous triple gauge-boson coupling parameters with the Standard Model is presented. The strategy removes the ambiguities of form factors, by reporting the limits as a function of a cuto operating on the diboson system invariant mass. (2) The `optimal observables' analysis strategy is investigated in the context of hadron colliders, and found to be not competitive, as compared to other strategies. (3) Techniques for measuring the energy dependence of anomalous couplings are presented .. .
Graduate
0798

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24

Nagel, Felix [Verfasser]. "New aspects of gauge boson couplings and the Higgs sector / presented by Felix Nagel." 2004. http://d-nb.info/972053832/34.

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Veverka, Jan. "Studies of Zγ Production and Constraints on Anomalous Triple Gauge Couplings in pp Collisions at √s = 7 TeV." Thesis, 2013. https://thesis.library.caltech.edu/7770/13/main_r413_optimized.pdf.

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In this thesis, we test the electroweak sector of the Standard Model of particle physics through the measurements of the cross section of the simultaneous production of the neutral weak boson Z and photon γ, and the limits on the anomalous Zγγ and ZZγ triple gauge couplings h3 and h4 with the Z decaying to leptons (electrons and muons). We analyze events collected in proton-proton collisions at center of mass energy of sqrt(s) = 7 TeV corresponding to an integrated luminosity of 5.0 inverse femtobarn. The analyzed events were recorded by the Compact Muon Solenoid detector at the Large Hadron Collider in 2011.

The production cross section has been measured for hard photons with transverse momentum greater than 15 GeV that are separated from the the final state leptons in the eta-phi plane by Delta R greater than 0.7, whose sum of the transverse energy of hadrons over the transverse energy of the photon in a cone around the photon with Delta R less than 0.3 is less than 0.5, and with the invariant mass of the dilepton system greater than 50 GeV. The measured cross section value is 5.33 +/- 0.08 (stat.) +/- 0.25 (syst.) +/- 0.12 (lumi.) picobarn. This is compatible with the Standard Model prediction that includes next-to-leading-order QCD contributions: 5.45 +/- 0.27 picobarn.

The measured 95 % confidence-level upper limits on the absolute values of the anomalous couplings h3 and h4 are 0.01 and 8.8E-5 for the Zγγ interactions, and, 8.6E-3 and 8.0E-5 for the ZZγ interactions. These values are also compatible with the Standard Model where they vanish in the tree-level approximation. They extend the sensitivity of the 2012 results from the ATLAS collaboration based on 1.02 inverse femtobarn of data by a factor of 2.4 to 3.1.

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Deng, Jianrong. "Measurement of Z +γ Production and Search for Anomalous Triple Gauge Couplings in Proton-antiproton Collisions at √S = 1.96 Tev." Diss., 2008. http://hdl.handle.net/10161/623.

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We present a measurement of ppbar->Zγ + X -> e⁺e^-γ + X production using proton-antiproton collision data collected at the Collider Detector at Fermilab at a center of mass energy of 1.96 TeV. Zγ production provides a direct test of the triple neutral gauge couplings. A measurement of Zγ production cross section and search for anomalous ZZγ and Zγγ couplings are presented. The data presented are from 1.1 fb^-1 of ppbar integrated luminosity collected at the CDF Detector. Electrons from Z decays are selected with E_t > 20 GeV. Photons (E_t > 7 GeV) are required to be well-separated from the electrons. There are 390 eeγ candidate events found with 1.1 fb^-1 of data, compared to the SM prediction of 375.3 Ã Â± 25.2 events. The Standard Model prediction for the cross section for ppbar-> e⁺e^-γ + X production at √s = 1.96 TeV is 4.5 Ã Â± 0.4 pb. The measured cross section is 4.7 Ã Â± 0.6 pb. The cross section and kinematic distributions of the eeγ events are in good agreement with theoretical predictions. Limits on the ZZγ and Zγγ couplings are extracted using the photon E_t distribution of eeγ events with M_eeγ > 100 GeV/c². These are the first limits measured using CDF Run II data. These limits provide important test of the interaction of the photon and the Z boson.
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Deng, Jianrong. "Measurement of Z + [gamma] Production and Search for Anomalous Triple Gauge Couplings in Proton-antiproton Collisions at [radical symbol]S = 1.96 Tev." Diss., 2008. http://hdl.handle.net/10161/623.

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Gumpert, Christian. "Measurement of Electroweak Gauge Boson Scattering in the Channel pp → W ± W ± jj with the ATLAS Detector at the Large Hadron Collider." Doctoral thesis, 2014. https://tud.qucosa.de/id/qucosa%3A28577.

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Particle physics deals with the elementary constituents of our universe and their interactions. The electroweak symmetry breaking mechanism in the Standard Model of Particle Physics is of paramount importance and it plays a central role in the physics programmes of current high-energy physics experiments at the Large Hadron Collider. The study of scattering processes of massive electroweak gauge bosons provides an approach complementary to the precise measurement of the properties of the recently discovered Higgs boson. Owing to the unprecedented energies achieved in proton-proton collisions at the Large Hadron Collider and the large amount of data collected, experimental studies of these processes become feasible for the first time. Especially the scattering of two W± bosons of identical electric charge is considered a promising process for an initial study due to its distinct experimental signature. In the course of this work, 20.3 fb−1 of proton-proton collision data recorded by the ATLAS detector at a centre-of-mass energy of √s = 8 TeV are analysed. An analysis of the production of two W± bosons of identical electric charge in association with two jets, pp → W ± W ± jj, is conducted in the leptonic decay channel of the W± bosons. Thereby, emphasis is put on the development of methods for the estimation of experimental backgrounds as well as on the optimisation of the event selection. As a result of this work, first experimental evidence for the existence of the aforementioned process is established with an observed significance of 4.9. Based on the number of observed events in the selected phase space the extracted fiducial cross section is σ(fid) = (2.3 ± 0.5(stat.) +0.4/−0.3 (sys.)) fb which is in agreement with the prediction of the Standard Model of σ(fid,SM) = (1.6 ± 0.2) fb. Of particular theoretical interest are electroweak contributions to the pp → W ± W ± jj process due to their sensitivity to the nature of the electroweak symmetry breaking mechanism. Criteria for a dedicated event selection are investigated and implemented in the analysis with the goal of enhancing the sensitivity to these contributions. First experimental evidence for the presence of electroweak contributions to the pp → W ± W ± jj process can be claimed with an observed significance of 4.1. The cross section extracted in the selected phase space region is found to be σ(fid) = (1.7 +0.5/−0.4 (stat.) ± 0.3(sys.)) fb which is 1.3 standard deviations above the theoretical prediction of the Standard Model of σ(fid,SM) = (1.0 ± 0.1) fb. A variety of extensions to the Standard Model predict modifications to the electroweak gauge sector. In the context of the electroweak chiral Lagrangian, which serves as an effective approximation of these theories in the energy regime E = 1 − 3 TeV, anomalous contributions to the quartic WWWW gauge coupling can be described by the parameters α4 and α5 . The selection of events is optimised again to enhance the sensitivity to these two parameters. On the basis of the number of events observed in this phase space region, the following one-dimensional confidence intervals at the 95% confidence level are derived: −0.09 ≤ α4 ≤ 0.10 and −0.15 ≤ α5 ≤ 0.15. At present, these limits represent the most stringent constraints on contributions from new physics processes to the quartic WWWW gauge coupling.

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Dissertations / Theses on the topic 'Triple Gauge Boson Couplings'

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