# ${\boldsymbol {\boldsymbol t}}$-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 ${{\boldsymbol p}}{{\boldsymbol p}}$ Collisions INSPIRE search

Spin correlation, f$_{SM}$, measures the strength of the correlation between the spins of the pair produced ${{\mathit t}}{{\overline{\mathit t}}}$. f$_{SM}$ =1 for the SM, while f$_{SM}$ =0 for no spin correlation.
VALUE DOCUMENT ID TECN  COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •
$1.12$ ${}^{+0.12}_{-0.15}$ 1
 2016 AI
CMS ${{\mathit \ell}}{{\mathit \ell}}$ + ${}\geq{}$2j (${}\geq{}1{{\mathit b}}$)
$0.72$ $\pm0.08$ ${}^{+0.15}_{-0.13}$ 2
 2016 X
CMS ${{\mathit \mu}}$ + 4,5j
$1.20$ $\pm0.05$ $\pm0.13$ 3
 2015 J
ATLS $\Delta \phi$( ${{\mathit \ell}}{{\mathit \ell}}$ ) in ${{\mathit \ell}}{{\mathit \ell}}+{}\geq{}$2j(${}\geq{}1{{\mathit b}}$)
$1.19$ $\pm0.09$ $\pm0.18$ 4
 2014 BB
ATLS $\Delta \phi$( ${{\mathit \ell}}{{\mathit \ell}}$ ) in ${{\mathit \ell}}{{\mathit \ell}}$ + ${}\geq{}$2j events
$1.12$ $\pm0.11$ $\pm0.22$ 4
 2014 BB
ATLS $\Delta \phi$( ${{\mathit \ell}}{{\mathit j}}$ ) in ${{\mathit \ell}}$ + ${}\geq{}$4j events
$0.87$ $\pm0.11$ $\pm0.14$ 4, 5
 2014 BB
ATLS S-ratio in ${{\mathit \ell}}{{\mathit \ell}}$ + ${}\geq{}$2j events
$0.75$ $\pm0.19$ $\pm0.23$ 4, 6
 2014 BB
ATLS cos$\theta ({{\mathit \ell}^{+}}$)cos$\theta ({{\mathit \ell}^{-}}$) in ${{\mathit \ell}}{{\mathit \ell}}$ + ${}\geq{}$2j events
$0.83$ $\pm0.14$ $\pm0.18$ 4, 7
 2014 BB
ATLS cos$\theta ({{\mathit \ell}^{+}}$)cos$\theta ({{\mathit \ell}^{-}}$) in ${{\mathit \ell}}{{\mathit \ell}}$ + ${}\geq{}$2j events
1  KHACHATRYAN 2016AI based on 19.5 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV, using lepton angular distributions as a function of the ${{\mathit t}}{{\overline{\mathit t}}}$ -system kinematical variables.
2  KHACHATRYAN 2016X based on 19.7 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. Uses a template fit method. Spin correlation strength in the helicity basis is given by $\mathit A_{{\mathrm {hel}}}$ = $0.23$ $\pm0.03$ ${}^{+0.05}_{-0.04}$.
3  AAD 2015J based on 20.3 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. Uses a fit including a linear superposition of ${{\mathit \Delta}}{{\mathit \phi}}$ distribution from the SM NLO simulation with coefficient ${{\mathit f}_{{SM}}}$ and from ${{\mathit t}}{{\overline{\mathit t}}}$ simulation without spin correlation with coefficient (1 $−$ ${{\mathit f}_{{SM}}}$).
4  Based on 4.6 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ =7 TeV. The results are for ${\mathit m}_{{{\mathit t}}}$ = 172.5 GeV.
5  The S-ratio is defined as the SM spin correlation in the like-helicity gluon-gluon collisions normalized to the no spin correlation case; see eq.(6) for the LO expression.
6  The polar angle correlation along the helicity axis.
7  The polar angle correlation along the direction which maximizes the correlation.
References:
 KHACHATRYAN 2016AI
PR D93 052007 Measurements of ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Spin Correlations and Top Quark Polarization using Dilepton Final States in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV
 KHACHATRYAN 2016X
PL B758 321 Measurement of Spin Correlations in ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Production using the Matrix Element Method in the Muon+Jets Final State in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV
PRL 114 142001 Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV Using the ATLAS Detector
PR D90 112016 Measurements of Spin Correlation in Top-Antitop Quark Events from Proton-Proton Collisions at $\sqrt {s }$ = 7 TeV using the ATLAS Detector