# ${\boldsymbol {\boldsymbol t}}$-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.

# ${{\boldsymbol F}_{{0}}}$ INSPIRE search

VALUE DOCUMENT ID TECN  COMMENT
$\bf{ 0.687 \pm0.018}$ OUR AVERAGE
$0.70$ $\pm0.05$ 1
 2017 BB
ATLS ${{\mathit F}_{{0}}}$ = 1 $−$ ${{\mathit f}_{{1}}}$
$0.681$ $\pm0.012$ $\pm0.023$ 2
 2016 BU
CMS ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
$0.726$ $\pm0.066$ $\pm0.067$ 3
 2013 D
CDF ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
$0.682$ $\pm0.030$ $\pm0.033$ 4
 2013 BH
CMS ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
$0.67$ $\pm0.07$ 5
 2012 BG
ATLS ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
$0.722$ $\pm0.062$ $\pm0.052$ 6
 2012 Z
TEVA ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
$0.669$ $\pm0.078$ $\pm0.065$ 7
 2011 C
D0 ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
$0.91$ $\pm0.37$ $\pm0.13$ 8
 2000 B
CDF ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
• • • We do not use the following data for averages, fits, limits, etc. • • •
$0.70$ $\pm0.07$ $\pm0.04$ 9
 2010 Q
CDF Repl. by AALTONEN 2012Z
$0.62$ $\pm0.10$ $\pm0.05$ 10
 2009 Q
CDF Repl. by AALTONEN 2010Q
$0.425$ $\pm0.166$ $\pm0.102$ 11
 2008 B
D0 Repl. by ABAZOV 2011C
$0.85$ ${}^{+0.15}_{-0.22}$ $\pm0.06$ 12
 2007 I
CDF ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
$0.74$ ${}^{+0.22}_{-0.34}$ 13
 2006 U
CDF ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
$0.56$ $\pm0.31$ 14
 2005 G
D0 ${{\mathit F}_{{0}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{0}}}{{\mathit b}}$ )
1  AABOUD 2017BB based on 20.2 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. Triple-differential decay rate of top quark in the ${{\mathit t}}$-channel single-top production is used to simultaneously determine five generalized ${{\mathit W}}{{\mathit t}}{{\mathit b}}$ couplings as well as the top polarization. No assumption is made for the other couplings. See this paper for constraints on other couplings not included here. The paper reported ${{\mathit f}_{{1}}}$, and we converted it to ${{\mathit F}_{{0}}}$.
2  KHACHATRYAN 2016BU based on 19.8 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV using ${{\mathit t}}{{\overline{\mathit t}}}$ events with ${{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$4 jets(${}\geq{}$2 ${{\mathit b}}$). The errors of ${{\mathit F}_{{0}}}$ and ${{\mathit F}_{{-}}}$ are correlated with a correlation coefficient $\rho ({{\mathit F}_{{0}}}$, ${{\mathit F}_{{-}}}$) = $-0.87$. The result is consistent with the NNLO SM prediction of $0.687$ $\pm0.005$ for ${\mathit m}_{{{\mathit t}}}$ = $172.8$ $\pm1.3$ GeV.
3  Based on 8.7 fb${}^{-1}$ of data in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\sqrt {s }$ = 1.96 TeV using ${{\mathit t}}{{\overline{\mathit t}}}$ events with ${{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$4 jets(${}\geq{}$1 ${{\mathit b}}$), and under the constraint F$_{0}$ + F$_{+}$ + F$_{-}$ = 1. The statstical errors of F$_{0}$ and F$_{+}$ are correlated with correlation coefficient $\rho (F_{0},F_{+}$) = $-0.69$.
4  Based on 5.0 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 TeV. CHATRCHYAN 2013BH studied events with large $\not E_T$ and ${{\mathit \ell}}$ +${}\geq{}$4 jets using a constrained kinematic fit.
5  Based on 1.04 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 TeV. AAD 2012BG studied events with large $\not E_T$ and either ${{\mathit \ell}}$ +${}\geq{}$4j or ${{\mathit \ell}}{{\mathit \ell}}$ +${}\geq{}$2j. The uncertainties are not independent, $\rho ({{\mathit F}_{{0}}},{{\mathit F}_{{-}}}$) = $-0.96$.
6  Based on 2.7 and 5.1 fb${}^{-1}$ of CDF data in ${{\mathit \ell}}$ + jets and dilepton channels, and 5.4 fb${}^{-1}$ of D0 data in ${{\mathit \ell}}$ + jets and dilepton channels. ${{\mathit F}_{{0}}}$ = $0.682$ $\pm0.035$ $\pm0.046$ if ${{\mathit F}_{{+}}}$ = 0.0017(1), while ${{\mathit F}_{{+}}}$ = $-0.015$ $\pm0.018$ $\pm0.030$ if ${{\mathit F}_{{0}}}$ = 0.688(4), where the assumed fixed values are the SM prediction for ${\mathit m}_{{{\mathit t}}}$ = $173.3$ $\pm1.1$ GeV and ${\mathit m}_{{{\mathit W}}}$ = $80.399$ $\pm0.023$ GeV.
7  Results are based on 5.4 fb${}^{-1}$ of data in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at 1.96 TeV, including those of ABAZOV 2008B. Under the SM constraint of ${{\mathit f}_{{0}}}$ = 0.698 (for ${\mathit m}_{{{\mathit t}}}$ = 173.3 GeV, ${\mathit m}_{{{\mathit W}}}$ = 80.399 GeV), ${{\mathit f}_{{+}}}$ = $0.010$ $\pm0.022$ $\pm0.030$ is obtained.
8  AFFOLDER 2000B studied the angular distribution of leptonic decays of ${{\mathit W}}$ bosons in ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}}{{\mathit b}}$ events. The ratio $\mathit F_{0}$ is the fraction of the helicity zero (longitudinal) ${{\mathit W}}~$bosons in the decaying top quark rest frame. B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}}_{+}$ ${{\mathit b}}$ ) is the fraction of positive helicity (right-handed) positive charge ${{\mathit W}}~$bosons in the top quark decays. It is obtained by assuming the Standard Model value of $\mathit F_{0}$.
9  Results are based on 2.7 fb${}^{-1}$ of data in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\sqrt {s }$ = 1.96 TeV. ${{\mathit F}_{{0}}}$ result is obtained by assuming ${{\mathit F}_{{+}}}$ = 0, while ${{\mathit F}_{{+}}}$ result is obtained for ${{\mathit F}_{{0}}}$ = 0.70, the SM value. Model independent fits for the two fractions give ${{\mathit F}_{{0}}}$ = $0.88$ $\pm0.11$ $\pm0.06$ and ${{\mathit F}_{{+}}}$ = $-0.15$ $\pm0.07$ $\pm0.06$ with correlation coefficient of $-0.59$. The results are for ${\mathit m}_{{{\mathit t}}}$ = 175 GeV.
10  Results are based on 1.9 fb${}^{-1}$ of data in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\sqrt {s }$ = 1.96 TeV. ${{\mathit F}_{{0}}}$ result is obtained assuming ${{\mathit F}_{{+}}}$ = 0, while ${{\mathit F}_{{+}}}$ result is obtained for ${{\mathit F}_{{0}}}$ = 0.70, the SM values. Model independent fits for the two fractions give ${{\mathit F}_{{0}}}$ = $0.66$ $\pm0.16$ $\pm0.05$ and ${{\mathit F}_{{+}}}$ = $-0.03$ $\pm0.06$ $\pm0.03$.
11  Based on 1 fb${}^{-1}$ at $\sqrt {s }$ = 1.96 TeV.
12  Based on 318 pb${}^{-1}$ of data at $\sqrt {s }$ = 1.96 TeV.
13  Based on 200 pb${}^{-1}$ of data at $\sqrt {s }$ = 1.96 TeV. ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}}{{\mathit b}}$ $\rightarrow$ ${{\mathit \ell}}{{\mathit \nu}}{{\mathit b}}$ (${{\mathit \ell}}$ = ${{\mathit e}}$ or ${{\mathit \mu}}$). The errors are stat + syst.
14  ABAZOV 2005G studied the angular distribution of leptonic decays of ${{\mathit W}}$ bosons in ${{\mathit t}}{{\overline{\mathit t}}}$ candidate events with lepton + jets final states, and obtained the fraction of longitudinally polarized ${{\mathit W}}$ under the constraint of no right-handed current, ${{\mathit F}_{{+}}}$ = 0. Based on 125 pb${}^{-1}$ of data at $\sqrt {s }$ = 1.8 TeV.
References:
 AABOUD 2017BB
JHEP 1712 017 Analysis of the $\mathit W_{tb}$ Vertex from the Measurement of Triple-Differential Angular Decay Rates of Single Top Quarks Produced in the t-Channel at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
 KHACHATRYAN 2016BU
PL B762 512 Measurement of the ${{\mathit W}}$ Boson Helicity Fractions in the Decays of Top Quark Pairs to Lepton + Jets Final States Produced in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV
 AALTONEN 2013D
PR D87 031104 Measurement of $\mathit W$-Boson Polarization in Top-Quark Decay using the Full CDF Run II Data Set
 CHATRCHYAN 2013BH
JHEP 1310 167 Measurement of the ${{\mathit W}}$-Boson Helicity in Top-Quark Decays from ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Production in Lepton+Jets Events in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 7 TeV
JHEP 1206 088 Measurement of the ${{\mathit W}}$ Boson Polarization in Top Quark Decays with the ATLAS Detector
 AALTONEN 2012Z
PR D85 071106 Combination of CDF and ${D0}$ Measurements of the ${{\mathit W}}$ Boson Helicity in Top Quark Decays
 ABAZOV 2011C
PR D83 032009 Measurement of the $\mathit W$ Boson Helicity in Top Quark Decays using 5.4 fb${}^{-1}$ of ${{\mathit p}}{{\overline{\mathit p}}}$ Collision Data
 AALTONEN 2010Q
PRL 105 042002 Measurement of ${{\mathit W}}$-Boson Polarization in Top-Quark Decay in Collisions at $\sqrt {s }$ = 1.96$~$TeV
 AALTONEN 2009Q
PL B674 160 Measurement of ${{\mathit W}}$-Boson Helicity Fractions in Top-Quark Decays using cos $\theta {}^{*}$
 ABAZOV 2008B
PRL 100 062004 Model-Independent Measurement of the ${{\mathit W}}$ Boson Helicity in Top Quark Decays at ${D0}$
 ABULENCIA 2007I
PR D75 052001 Measurement of the Helicity Fractions of ${{\mathit W}}$ Bosons from top Quark Decays using Fully Reconstructed ${\mathit {\mathit t}}$ ${\mathit {\overline{\mathit t}}}$ Events with CDF II
 ABULENCIA 2006U
PR D73 111103 Measurement of the Helicity of $\mathit W$ Bosons in top-Quark Decays
 ABAZOV 2005G
PL B617 1 Helicity of the ${{\mathit W}}$ Boson in Lepton $+$ Jets ${{\mathit t}}{{\overline{\mathit t}}}$ Events
 AFFOLDER 2000B
PRL 84 216 Measurement of the Helicity of ${{\mathit W}}$ Bosons in Top Quark Decays