# ${\boldsymbol {\boldsymbol t}}$-quark EW Couplings

${{\mathit W}}$ helicity fractions in top decays. ${{\mathit F}_{{0}}}$ is the fraction of longitudinal and ${{\mathit F}_{{+}}}$ the fraction of right-handed ${{\mathit W}}$ bosons. ${{\mathit F}_{{{V+A}}}}$ is the fraction of $\mathit V+\mathit A$ current in top decays. The effective Lagrangian (cited by ABAZOV 2008AI) has terms f${}^{L}_{1}$ and f${}^{R}_{1}$ for $\mathit V−\mathit A$ and $\mathit V+\mathit A$ couplings, f${}^{L}_{2}$ and f${}^{R}_{2}$ for tensor couplings with b$_{R}$ and b$_{L}$ respectively.

# Spin Correlation in ${{\boldsymbol t}}{{\overline{\boldsymbol t}}}$ Production in ${{\boldsymbol p}}{{\overline{\boldsymbol p}}}$ Collisions INSPIRE search

C is the correlation strength parameter, f is the ratio of events with correlated ${{\mathit t}}$ and ${{\overline{\mathit t}}}$ spins (SM prediction: f = 1), and $\kappa$ is the spin correlation coefficient. See "The Top Quark" review for more information.
VALUE DOCUMENT ID TECN  COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •
$0.89$ $\pm0.22$ 1
 2016 A
D0 f ( ${{\mathit \ell}}{{\mathit \ell}}$ +${}\geq{}$2 jets, ${{\mathit \ell}}$ +${}\geq{}$4 jets)
$0.85$ $\pm0.29$ 2
 2012 B
D0 f ( ${{\mathit \ell}}{{\mathit \ell}}$ +${}\geq{}$2 jets, ${{\mathit \ell}}$ +${}\geq{}$4 jets)
$1.15$ ${}^{+0.42}_{-0.43}$ 3
 2012 B
D0 f (${{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$4 jets)
$0.60$ ${}^{+0.50}_{-0.16}$ 4
 2011 AR
CDF ${{\mathit \kappa}}$ (${{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$4 jets)
$0.74$ ${}^{+0.40}_{-0.41}$ 5
 2011 AE
D0 f ( ${{\mathit \ell}}{{\mathit \ell}}$ +$\not E_T$ + ${}\geq{}$2 jets)
$0.10$ $\pm0.45$ 6
 2011 AF
D0 C ( ${{\mathit \ell}}{{\mathit \ell}}$ +$\not E_T$ + ${}\geq{}$2 jets)
1  ABAZOV 2016A based on 9.7 fb${}^{-1}$ of data. A matrix element method is used. It corresponds to evidence of spin correlation at 4.2${{\mathit \sigma}}$ and is in agreement with the NLO SM prediction $0.80$ ${}^{+0.01}_{-0.02}$.
2  This is a combination of the lepton + jets analysis presented in ABAZOV 2012B and the dilepton measurement of ABAZOV 2011AE. It provides a 3.1 ${{\mathit \sigma}}$ evidence for the ${{\mathit t}}{{\overline{\mathit t}}}$ spin correlation.
3  Based on 5.3 fb${}^{-1}$ of data. The error is statistical and systematic combined. A matrix element method is used.
4  Based on 4.3 fb${}^{-1}$ of data. The measurement is based on the angular study of the top quark decay products in the helicity basis.The theory prediction is ${{\mathit \kappa}}$ $\approx{}$ 0.40.
5  Based on 5.4 fb${}^{-1}$ of data using a matrix element method. The error is statistical and systematic combined. The no-correlation hypothesis is excluded at the 97.7$\%$ CL.
6  Based on 5.4 fb${}^{-1}$ of data. The error is statistical and systematic combined. The NLO QCD prediction is C = $0.78$ $\pm0.03$. The neutrino weighting method is used for reconstruction of kinematics.
References:
 ABAZOV 2016A
PL B757 199 Measurement of Spin Correlation between Top and Antitop Quarks Produced in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.96 TeV
 ABAZOV 2012B
PRL 108 032004 Evidence for Spin Correlation in ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Production
 AALTONEN 2011AR
PR D83 031104 Measurement of ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Spin Correlation in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions Using the CDF II Detector at the Tevatron
 ABAZOV 2011AF
PL B702 16 Measurement of Spin Correlation in ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Production using Dilepton Final States
 ABAZOV 2011AE
PRL 107 032001 Measurement of Spin Correlation in ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Production using a Matrix Element Approach