${\mathit {\mathit t}}$-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.

${\mathit \sigma (}{{\mathit H}}{{\mathit t}}{{\overline{\mathit t}}}{)}$ /${\mathit \sigma (}{{\mathit H}}{{\mathit t}}{{\overline{\mathit t}}}{)}_{SM}$

INSPIRE   PDGID:
Q007TTH
VALUE CL% DOCUMENT ID TECN  COMMENT
• • We do not use the following data for averages, fits, limits, etc. • •
$1.43$ ${}^{+0.33}_{-0.31}$ ${}^{+0.21}_{-0.15}$ 1
AAD
2020Z
 ATLS ${{\mathit H}}{{\mathit t}}{{\overline{\mathit t}}}$ ( ${{\mathit H}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$)
$1.38$ ${}^{+0.29}_{-0.27}$ ${}^{+0.21}_{-0.11}$ 2
SIRUNYAN
2020AS
 CMS ${{\mathit H}}{{\mathit t}}{{\overline{\mathit t}}}$ ( ${{\mathit H}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$)
$0.72$ $\pm0.24$ $\pm0.38$ 3
SIRUNYAN
2019R
 CMS ${{\mathit H}}{{\mathit t}}{{\overline{\mathit t}}}$ ( ${{\mathit H}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$ , ${{\mathit t}}{{\overline{\mathit t}}}$ $\rightarrow$ ${{\mathit \ell}}$+jets or dilepton)
$0.9$ $\pm0.7$ $\pm1.3$ 4
SIRUNYAN
2018BD
 CMS ${{\mathit H}}{{\mathit t}}{{\overline{\mathit t}}}$ ( ${{\mathit H}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$ , ${{\mathit t}}{{\overline{\mathit t}}}$ $\rightarrow$ all jets)
$1.26$ ${}^{+0.31}_{-0.26}$ 5
SIRUNYAN
2018L
 CMS combination of CMS
$<6.7$ 95 6
AAD
2015
ATLS ${{\mathit H}}{{\mathit t}}{{\overline{\mathit t}}}$; ${{\mathit H}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$
$2.8$ $\pm1.0$ 7
KHACHATRYAN
2014H
 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  AAD 2020Z based on 139 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at 13 TeV. Assuming a $\mathit CP$-even coupling the ${{\mathit t}}{{\overline{\mathit t}}}{{\mathit H}}$ process is observed with a significance of 5.2 $\sigma $, and the measured $\sigma _{{{\mathit t}} {{\overline{\mathit t}}} {{\mathit H}}}\cdot{}\mathit B_{{{\mathit \gamma}} {{\mathit \gamma}}}$ = $1.64$ ${}^{+0.38}_{-0.36}{}^{+0.17}_{-0.14}$ fb. A $\mathit CP$-mixing angle $\vert \alpha \vert $ $>$ 43$^\circ{}$ is excluded at 95$\%$ CL.
2  SIRUNYAN 2020AS based on 137 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at 13 TeV. The ${{\mathit t}}{{\overline{\mathit t}}}{{\mathit H}}$ process is observed with a significance of 6.6 $\sigma $, and the measured $\sigma _{{{\mathit t}} {{\overline{\mathit t}}} {{\mathit H}}}\cdot{}\mathit B_{{{\mathit \gamma}} {{\mathit \gamma}}}$ = $1.56$ ${}^{+0.33}_{-0.30}{}^{+0.09}_{-0.08}$ fb. The fractional contribution of the $\mathit CP$-odd component is measured to be f${}^{{{\mathit t}} {{\overline{\mathit t}}} {{\mathit H}}}_{CP}$ = $0.00$ $\pm0.33$.
3  SIRUNYAN 2019R based on 35.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at 13 TeV. Multivariate techniques are employed to separate the signal from the dominant ${{\mathit t}}{{\overline{\mathit t}}}$+jets background. The result is for ${\mathit m}_{{{\mathit H}}}$ = 125 GeV. The measured ratio corresponds to a signal significance of 1.6$\sigma $ above the background-only hypothesis.
4  SIRUNYAN 2018BD based on 35.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at 13 TeV. A combined fit of signal and background templates to data is performed in six event categories separated by jet and ${{\mathit b}}$-jet multiplicities. An upper limit of 3.8 is obtained for the cross section ratio.
5  SIRUNYAN 2018L based on up to 5.1, 19.7, and 35.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at 7, 8, and 13 TeV, respectively. An excess of events is observed, with a significance of 5.2 standard deviations, over the expectation from the background-only hypothesis. The result is for the Higgs boson mass of 125.09 GeV.
6  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).
7  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