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


• • We do not use the following data for averages, fits, limits, etc. • •
$-0.08 < f{}^{L}_{2} < 0.05$ 95 1
LHC ATLAS+CMS combined
$\vert f{}^{L}_{2}/f{}^{L}_{1}\vert < 0.29$ 95 2
ATLS ${{\mathit t}}$-channel single top
$ \vert f{}^{L}_{2}\vert < 0.057$ 95 3
CMS ${{\mathit t}}$-channel single-${{\mathit t}}$ prod.
$-0.14< Re(f{}^{L}_{2})< 0.11$ 95 4
ATLS Constr. on ${{\mathit W}}{{\mathit t}}{{\mathit b}}$ vtx
$(\mathit V_{\mathit tb} \text{ f}{}^{L}_{2}){}^{2} < 0.13$ 95 5
D0 Single-top
$\vert f{}^{L}_{2}\vert ^2 < 0.05$ 95 6
D0 single-${{\mathit t}}$ + ${{\mathit W}}$ helicity
$\vert f{}^{L}_{2}\vert ^2 < 0.28$ 95 7
D0 $\vert $f${}^{L}_{1}\vert $ = 1, $\vert $f${}^{R}_{1}\vert =\vert $f${}^{R}_{2}\vert $=0
$\vert f{}^{L}_{2}\vert ^2 < 0.5$ 95 8
D0 $\vert $f${}^{L}_{1}\vert ^2$ = $1.4$ ${}^{+0.6}_{-0.5}$
1  AAD 2020Y based on about 20 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV for each experiment. The measurements used events with one lepton and different jet multiplicities in the final state. The measurements of $\mathit F_{0}$ and $\mathit F_{-}$ are used to set the limit. The limit is obtained by assuming the other couplings to have their SM values.
2  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 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.
3  KHACHATRYAN 2017G based on 5.0 and 19.7 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 and 8 TeV, respectively. A Bayesian neural network technique is used to discriminate between signal and backgrounds. This is a 95$\%$ CL exclusion limit obtained by a three-dimensional fit with simultaneous variation of (f${}^{L}_{1}$, f${}^{L}_{2}$, f${}^{R}_{2}$).
4  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{}$2j.
5  Based on 5.4 fb${}^{-1}$ of data. For each value of the form factor quoted the other two are assumed to have their SM value. Their Fig. 4 shows two-dimensional posterior probability density distributions for the anomalous couplings.
6  Based on 5.4 fb${}^{-1}$ of data in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at 1.96 TeV. Results are obtained by combining the limits from the ${{\mathit W}}$ helicity measurements and those from the single top quark production.
7  Based on 1 fb${}^{-1}$ of data at ${{\mathit p}}{{\overline{\mathit p}}}$ collisions $\sqrt {s }$ = 1.96 TeV. Combined result of the ${{\mathit W}}$ helicity measurement in ${{\mathit t}}{{\overline{\mathit t}}}$ events (ABAZOV 2008B) and the search for anomalous ${{\mathit t}}{{\mathit b}}{{\mathit W}}$ couplings in the single top production (ABAZOV 2008AI). Constraints when f${}^{L}_{1}$ and one of the anomalous couplings are simultaneously allowed to vary are given in their Fig. 1 and Table 1.
8  Result is based on 0.9 fb${}^{-1}$ of data at $\sqrt {s }$ = 1.96 TeV. Single top quark production events are used to measure the Lorentz structure of the ${{\mathit t}}{{\mathit b}}{{\mathit W}}$ coupling. The upper bounds on the non-standard couplings are obtained when only one non-standard coupling is allowed to be present together with the SM one, f${}^{L}_{1}$ = V${}^{*}_{{{\mathit t}} {{\mathit b}}}$.