# ${{\boldsymbol t}}$-quark Polarization in Single Top Events in ${{\boldsymbol p}}{{\boldsymbol p}}$ Collisions at $\sqrt {s }$ = 8 TeV INSPIRE search

VALUE CL% DOCUMENT ID TECN  COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •
$>0.72$ 95 1
 2017 BB
ATLS ${{\mathit \alpha}_{{{{\mathit \ell}}}}}\mathit P$; t-channel
$0.97$ $\pm0.05$ $\pm0.11$ 2
 2017 I
ATLS $\alpha _{{{\mathit \ell}}}\mathit P$; t-channel
$0.25$ $\pm0.08$ $\pm0.14$ 3
 2017 I
ATLS ($\mathit F_{+}+\mathit F_{-})\mathit P$; t-channel
$0.26$ $\pm0.03$ $\pm0.10$ 4
 2016 BO
CMS ($\alpha _{{{\mathit \mu}}}\mathit P$)/2; t-channel
1  AABOUD 2017BB based on 20.2 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data. 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. ${{\mathit \alpha}_{{{{\mathit \ell}}}}}$ denotes the spin analyzing power of charged lepton, and the spin axis of the top polarization $\mathit P$ is taken along the spectator-quark momentum in the top rest frame. The value is compatible with the SM prediction of about 0.9.
2  AABOUD 2017I based on 20.2 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data. A cut-based analysis is used to discriminate between signal and backgrounds. $\alpha _{{{\mathit \ell}}}$ denotes the spin analyzing power of charged lepton, and the spin axis of the top polarization $\mathit P$ is taken along the spectator-quark momentum in the top rest frame. See this paper for a number of other asymmetries and measurements that are not included here.
3  AABOUD 2017I based on 20.2 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data. A cut-based analysis is used to discriminate between signal and backgrounds. $\mathit F_{\pm{}}$ denotes ${{\mathit W}}$ helicity fraction, and the spin axis of the top polarization $\mathit P$ is taken along the spectator-quark momentum in the top rest frame. See this paper for a number of other asymmetries and measurements that are not included here.
4  KHACHATRYAN 2016BO based on 19.7 fb${}^{-1}$ of data. A high-purity sample with a muon is selected by a multivariate analysis. The value is the top spin asymmetry, given by one half of the spin analyzing power $\alpha _{{{\mathit \mu}}}$ (=1 at LO of SM) times the top polarization, $\mathit P$, where the spin axis is defined as the direction of the untagged jet in the top rest frame. The value is compatible with the SM prediction of 0.44 with a 2.0$\sigma$ deviation.
References:
 AABOUD 2017I
JHEP 1704 124 Probing the ${{\mathit W}}{\mathit {\mathit t}}{\mathit {\mathit b}}$ Vertex Structure in ${{\mathit t}}$-Channel Single-top-Quark Production and Decay in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
 AABOUD 2017BB
JHEP 1712 017 Analysis of the $\mathit W_{tb}$ Vertex from the Measurement of Triple-Differential Angular Decay Rates of Single Top Quarks Produced in the t-Channel at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
 KHACHATRYAN 2016BO
JHEP 1604 073 Measurement of Top Quark Polarisation in $\mathit t$-Channel Single Top Quark Production