Measurements Of T Bar T Spin Correlations And Top Quark Polarization Using Dilepton Final States In Pp Collisions At Sqrt S
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Measurements Of T Bar T Spin Correlations And Top Quark Polarization Using Dilepton Final States In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2013
Measurements Of T Bar T Spin Correlations And Top Quark Polarization Using Dilepton Final States In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1995
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Aeronautics categories.
Measurements Of T T Spin Correlations And Top Quark Polarization Using Dilepton Final States In Pp Collisions At S
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Author : CMS Collaboration
language : en
Publisher:
Release Date : 2016
Measurements Of T T Spin Correlations And Top Quark Polarization Using Dilepton Final States In Pp Collisions At S written by CMS Collaboration and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Measurements Of Tt U00af Spin Correlations And Top Quark Polarization Using Dilepton Final States In Pp Collisions At S
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Author :
language : en
Publisher:
Release Date : 2016
Measurements Of Tt U00af Spin Correlations And Top Quark Polarization Using Dilepton Final States In Pp Collisions At S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
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.
Spin Correlations In Tt Events From Pp Collisions
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Author : Boris Lemmer
language : en
Publisher:
Release Date : 2015
Spin Correlations In Tt Events From Pp Collisions written by Boris Lemmer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
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.
Measurement Of Spin Correlation Between Top And Antitop Quarks Produced In P Bar P Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Measurement Of Spin Correlation Between Top And Antitop Quarks Produced In P Bar P Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
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.
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
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Author :
language : en
Publisher:
Release Date : 2016
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 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
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.
Measurement Of Spin Correlations In Top Anti Top Events From Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2014
Measurement Of Spin Correlations In Top Anti Top Events From Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
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 ...
Measurement Of The Ratio B T To Wb B T To Wq In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2014
Measurement Of The Ratio B T To Wb B T To Wq In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The ratio of the top-quark branching fractions R=B(t to Wb)/B(t to Wq), where the denominator includes the sum over all down-type quarks (q = b, s, d), is measured in the t t-bar dilepton final state with proton-proton collision data at sqrt(s)=8 TeV from an integrated luminosity of 19.7 inverse femtobarns, collected with the CMS detector. In order to quantify the purity of the signal sample, the cross section is measured by fitting the observed jet multiplicity, thereby constraining the signal and background contributions. By counting the number of b jets per event, an unconstrained value of R=1.014 +/- 0.003 (stat.) +/- 0.032 (syst.) is measured, in good agreement with the standard model prediction. A lower limit R> 0.955 at the 95% confidence level is obtained after requiring R ;=1, and a lower limit on the Cabibbo-Kobayashi-Maskawa matrix element abs(V[tb]) 0.975 is set at 95% confidence level. The result is combined with a previous CMS measurement of the t-channel single-top-quark cross section to determine the top-quark total decay width, Gamma[t]=1.36 +/- 0.02 (stat.) +0.14/-0.11 (syst.) GeV.
Measurement Of Top Quark Polarization In T Overline T Lepton Jets Final States
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Author :
language : en
Publisher:
Release Date : 2016
Measurement Of Top Quark Polarization In T Overline T Lepton Jets Final States written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
We present a study of top quark polarization in $t \overline{t}$ events produced in $p \overline{p}$ collisions at $\sqrt{s}=1.96$ TeV. Data correspond to 9.7 fb$^{-1}$ collected with the D0 detector at the Tevatron. We use final states containing a lepton and at least three jets. The polarization is measured using the distribution of leptons along the beam and helicity axes, and the axis normal to the production plane. This is the first measurement of top quark polarization at the Tevatron in $\ell$+jets final states, and first measurement of transverse polarization in $t \overline{t}$ production. The observed distributions are consistent with the standard model.