Measurements Of Ttu00af Spin Correlations And Top Quark Polarization Using Dilepton Final States In Pp Collisions At S PDF Download
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| Release | : 2016 |
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Download Measurements of Tt{u00AF} Spin Correlations and Top Quark Polarization Using Dilepton Final States in Pp Collisions at S Book in PDF, ePub and Kindle
We presented measurements of the top quark-antiquark (tt¯) spin correlations and the top quark polarization for tt¯ pairs produced in pp collisions at √s=8 TeV. The data correspond to an integrated luminosity of 19.5 fb-1 collected with the CMS detector at the LHC. The measurements are performed using events with two oppositely charged leptons (electrons or muons) and two or more jets, where at least one of the jets is identified as originating from a bottom quark. The spin correlations and polarization are measured from the angular distributions of the two selected leptons, both inclusively and differentially, with respect to the invariant mass, rapidity, and transverse momentum of the tt¯ system. Moreover, the measurements are unfolded to the parton level and found to be in agreement with predictions of the standard model. A search for new physics in the form of anomalous top quark chromo moments is performed. Lastly, no evidence of new physics is observed, and exclusion limits on the real part of the chromo-magnetic dipole moment and the imaginary part of the chromo-electric dipole moment are evaluated.
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| Total Pages | : 27 |
| Release | : 2013 |
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Download Measurements of $t\bar{t}$ Spin Correlations and Top-quark Polarization Using Dilepton Final States in Pp Collisions at $\sqrt{s}$ Book in PDF, ePub and Kindle
| Author | : CMS Collaboration |
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| Release | : 2016 |
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Download Measurements of T ̄t Spin Correlations and Top Quark Polarization Using Dilepton Final States in Pp Collisions at √s Book in PDF, ePub and Kindle
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| Total Pages | : 249 |
| Release | : 2014 |
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Download Measurement of Spin Correlations in Top/Anti-Top Events from Pp Collisions at Sqrt(s) Book in PDF, ePub and Kindle
The top quark decays before it hadronises. Before its spin state can be changed in a process of strong interaction, it is directly transferred to the top quark decay products. The top quark spin can be deduced by studying angular distributions of the decay products. The Standard Model predicts the top/anti-top quark (tt) pairs to have correlated spins. The degree is sensitive to the spin and the production mechanisms of the top quark. Measuring the spin correlation allows to test the predictions. New physics e ects can be reflected in deviations from the prediction. In this thesis the spin ...
| Author | : Boris Lemmer |
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| Total Pages | : 0 |
| Release | : 2015 |
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| ISBN | : 9783319189338 |
Download Spin Correlations in Tt Events from Pp Collisions Book in PDF, ePub and Kindle
This thesis introduces readers to the Standard Model, the top quark and its properties, before explaining the concept of spin correlation measurement. The first measurement of top quark spin correlations at the LHC in the lepton+jets decay channel is presented. As the heaviest elementary particle, the top quark plays an essential role in the Standard Model of elementary particle physics. In the case of top quarks being produced in pairs at hadron colliders, the Standard Model predicts their spins to be correlated. The degree of correlation depends on both the production mechanism and properties of the top quark. Any deviation from the Standard Model prediction can be an indicator for new physics phenomena. The thesis employs an advanced top quark reconstruction algorithm including dedicated identification of the up- and down-type quarks from the W boson decay.
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| Release | : 2015 |
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Download Measurement of Spin Correlation Between Top and Antitop Quarks Produced in $p\bar{p}$ Collisions at $\sqrt{s} Book in PDF, ePub and Kindle
We present a measurement of the correlation between the spins of t and tbar quarks produced in proton-antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96 TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the D0 detector that correspond to an integrated luminosity of 9.7 fb$^{-1}$. The measured value of the correlation coefficient in the off-diagonal basis, $O_{off} = 0.89 \pm 0.22$ (stat + syst), is in agreement with the standard model prediction, and represents evidence for a top-antitop quark spin correlation difference from zero at a level of 4.2 standard deviations.
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| Total Pages | : 117 |
| Release | : 2012 |
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Download Measurement of the Spin Correlation in the Top Quark Pair Production Using the Dilepton Events in 1.96-TeV Proton-Antiproton Collisions Book in PDF, ePub and Kindle
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| Total Pages | : 26 |
| Release | : 2016 |
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Download Measurement of Spin Correlations in T-tbar Production Using the Matrix Element Method in the Muon+jets Final State in Pp Collisions at {u221A}(s) Book in PDF, ePub and Kindle
The consistency of the spin correlation strength in top quark pair production with the standard model (SM) prediction is tested in the muon+jets final state. The events are selected from pp collisions, collected by the CMS detector, at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. We then compare the data with the expectation for the spin correlation predicted by the SM and with the expectation of no correlation. Furthermore, by using a template fit method, the fraction of events that show SM spin correlations is measured to be 0.72 ±0.08 (stat)+0.15 -0.13 (syst), representing the most precise measurement of this quantity in the lepton+jets final state to date.
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| Total Pages | : 8 |
| Release | : 2010 |
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Download Top Quark Spin Correlations at the Tevatron Book in PDF, ePub and Kindle
Recent measurements of the correlation between the spin of the top and the spin of the anti-top quark produced in proton anti-proton scattering at a center of mass energy of (square root)s = 1.96 Tev by the CDF and D0 collaborations are discussed. using up to 4.3 fb−1 of data taken with the CDF and D0 detectors the spin correlation parameter C, the degree to which the spins are correlated, is measured in dileptonic and semileptonic final states. The measurements are found to be in agreement with Standard Model predictions.
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| Release | : 2017 |
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Download Measurement of Top Quark Polarization in Top-antitop Lepton+jets Final States at Book in PDF, ePub and Kindle
This thesis presents a measurement of the top quark polarization in the $t\overline{t}$ events produced in $p\overline{p}$ collisions at $\sqrt{s}=1.96$ TeV using data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The final states used in the measurement contain one lepton and at least three jets. The polarization is measured using the angular distribution of leptons along three different axes: the beam axis, the helicity axis, and the transverse axis normal to the $t\overline{t}$ production plane. This is the first measurement of top quark polarization at the Tevatron Collider in lepton+jets final states, and the first measurement of transverse polarization in $t\overline{t}$ production. The polarization along the beam axis is combined with the previous result in the dilepton final states by the D0 experiment. The observed distributions are consistent with the Standard Model of nearly no polarization and no indication for beyond Standard Model physics is observed. The measurement offers legacy result from unique Tevatron Collider data and provides more information about the top quark production and decays, about the properties of the heaviest elementary particle.
