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

${{\mathit F}_{{{{V+A}}}}}$

INSPIRE   PDGID:
Q007TV2
VALUE CL% DOCUMENT ID TECN  COMMENT
$\bf{<0.29}$ 95 1
ABULENCIA
2007G
 CDF ${{\mathit F}_{{{{V+A}}}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}}{{\mathit b}_{{{R}}}}$)
• • We do not use the following data for averages, fits, limits, etc. • •
$-0.06$ $\pm0.22$ $\pm0.12$ 1
ABULENCIA
2007G
 CDF ${{\mathit F}_{{{{V+A}}}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}}{{\mathit b}_{{{R}}}}$)
$<0.80$ 95 2
ACOSTA
2005D
 CDF ${{\mathit F}_{{{{V+A}}}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}}{{\mathit b}_{{{R}}}}$)
1  Based on 700 pb${}^{-1}$ of data at $\sqrt {s }$ = 1.96 TeV.
2  ACOSTA 2005D measures the ${{\mathit m}^{2}}_{{{\mathit \ell}} {+} {{\mathit b}}}$ distribution in ${{\mathit t}}{{\overline{\mathit t}}}$ production events where one or both ${{\mathit W}}$'s decay leptonically to ${{\mathit \ell}}$ = ${{\mathit e}}$ or ${{\mathit \mu}}$, and finds a bound on the V+A coupling of the ${{\mathit t}}{{\mathit b}}{{\mathit W}}$ vertex. By assuming the SM value of the longitudinal ${{\mathit W}}$ fraction ${{\mathit F}_{{{0}}}}$ = B( ${{\mathit t}}$ $\rightarrow$ ${{\mathit W}_{{{0}}}}{{\mathit b}}$) = 0.70, the bound on ${{\mathit F}}_{+}$ is obtained. If the results are combined with those of AFFOLDER 2000B, the bounds become ${{\mathit F}}_{V+A}$ $<$ 0.61 (95$\%$ CL) and ${{\mathit F}_{{{+}}}}$ $<$ 0.18 (95 $\%$CL), respectively. Based on $109$ $\pm7$ pb${}^{-1}$ of data at $\sqrt {s }$ = 1.8 TeV (run I).
References