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

# ${\boldsymbol \sigma (}$ ${{\boldsymbol H}}{{\boldsymbol t}}{{\overline{\boldsymbol t}}}{)}$ /${\boldsymbol \sigma (}$ ${{\boldsymbol H}}{{\boldsymbol t}}{{\overline{\boldsymbol t}}}{)}_{SM}$ INSPIRE search

VALUE CL% DOCUMENT ID TECN  COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •
$<6.7$ 95 1
 2015
ATLS ${{\mathit H}}{{\mathit t}}{{\overline{\mathit t}}}$ ; ${{\mathit H}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$
$2.8$ $\pm1.0$ 2
 2014 H
CMS ${{\mathit H}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$ , ${{\mathit \tau}_{{h}}}{{\mathit \tau}_{{h}}}$ , ${{\mathit \gamma}}{{\mathit \gamma}}$ , ${{\mathit W}}{{\mathit W}}$ $/$ ${{\mathit Z}}{{\mathit Z}}$ (leptons)
1  Based on 4.5 fb${}^{-1}$ of data at 7 TeV and 20.3 fb${}^{-1}$ at 8 TeV. The result is for ${\mathit m}_{{{\mathit H}}}$ = 125.4 GeV. The measurement constrains the top quark Yukawa coupling strength parameter $\kappa _{t}$ = ${{\mathit Y}_{{t}}}/{{\mathit Y}_{{t}}^{SM}}$ to be $-1.3$ $<$ $\kappa _{t}$ $<$ 8.0 (95$\%$ CL).
2  Based on 5.1 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at 7 TeV and 19.7 fb${}^{-1}$ at 8 TeV. The results are obtained by assuming the SM decay branching fractions for the Higgs boson of mass 125.6 GeV. The signal strength for individual Higgs decay channels are given in Fig. 13, and the preferred region in the ($\kappa _{V}$, $\kappa _{f}$) space is given in Fig. 14.
References:
PL B740 222 Search for ${{\mathit H}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$ Produced in Association with Top Quarks and Constraints on the Yukawa Coupling between the Top Quark and the Higgs Boson using Data Taken at 7 TeV and 8 TeV with the ATLAS Detector