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

Spin Correlation in ${{\mathit t}}{{\overline{\mathit t}}}$ Production in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions INSPIRE search

C is the correlation strength parameter, f is the ratio of events with correlated ${{\mathit t}}$ and ${{\overline{\mathit t}}}$ spins (SM prediction: f = 1), and $\kappa $ is the spin correlation coefficient. See "The Top Quark" review for more information.

Q007SC

VALUE

DOCUMENT ID

TECN

COMMENT

• • • We do not use the following data for averages, fits, limits, etc. • • •

$0.89$ $\pm0.22$

ABAZOV

2016

f (${{\mathit \ell}}{{\mathit \ell}}$ +${}\geq{}$2 jets, ${{\mathit \ell}}$ +${}\geq{}$4 jets)

$0.85$ $\pm0.29$

ABAZOV

2012

f (${{\mathit \ell}}{{\mathit \ell}}$ +${}\geq{}$2 jets, ${{\mathit \ell}}$ +${}\geq{}$4 jets)

$1.15$ ${}^{+0.42}_{-0.43}$

ABAZOV

2012

f (${{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$4 jets)

$0.60$ ${}^{+0.50}_{-0.16}$

⁴

AALTONEN

2011

CDF

${{\mathit \kappa}}$ (${{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$4 jets)

$0.74$ ${}^{+0.40}_{-0.41}$

⁵

ABAZOV

2011

f (${{\mathit \ell}}{{\mathit \ell}}$ +$\not E_T$ + ${}\geq{}$2 jets)

$0.10$ $\pm0.45$

⁶

ABAZOV

2011

C (${{\mathit \ell}}{{\mathit \ell}}$ +$\not E_T$ + ${}\geq{}$2 jets)

¹ ABAZOV 2016A based on 9.7 fb${}^{-1}$ of data. A matrix element method is used. It corresponds to evidence of spin correlation at 4.2${{\mathit \sigma}}$ and is in agreement with the NLO SM prediction $0.80$ ${}^{+0.01}_{-0.02}$.

² This is a combination of the lepton + jets analysis presented in ABAZOV 2012B and the dilepton measurement of ABAZOV 2011AE. It provides a 3.1 ${{\mathit \sigma}}$ evidence for the ${{\mathit t}}{{\overline{\mathit t}}}$ spin correlation.

³ Based on 5.3 fb${}^{-1}$ of data. The error is statistical and systematic combined. A matrix element method is used.

⁴ Based on 4.3 fb${}^{-1}$ of data. The measurement is based on the angular study of the top quark decay products in the helicity basis.The theory prediction is ${{\mathit \kappa}}$ $\approx{}$ 0.40.

⁵ Based on 5.4 fb${}^{-1}$ of data using a matrix element method. The error is statistical and systematic combined. The no-correlation hypothesis is excluded at the 97.7$\%$ CL.

⁶ Based on 5.4 fb${}^{-1}$ of data. The error is statistical and systematic combined. The NLO QCD prediction is C = $0.78$ $\pm0.03$. The neutrino weighting method is used for reconstruction of kinematics.

References:

ABAZOV

2016A

PL B757 199

Measurement of Spin Correlation between Top and Antitop Quarks Produced in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.96 TeV

ABAZOV

2012B

PRL 108 032004

Evidence for Spin Correlation in ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Production

AALTONEN

2011AR

PR D83 031104

Measurement of ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Spin Correlation in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions Using the CDF II Detector at the Tevatron

ABAZOV

2011AF

PL B702 16

Measurement of Spin Correlation in ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Production using Dilepton Final States

ABAZOV

2011AE

PRL 107 032001

Measurement of Spin Correlation in ${\mathit {\mathit t}}{\mathit {\overline{\mathit t}}}$ Production using a Matrix Element Approach