Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at s$$ \sqrt{s} $$ = 13 TeV

Abstract

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric

d ̂

t

$$ \left({\hat{d}}_{\mathrm{t}}\right) $$ and chromomagnetic

μ ̂

t

$$ \left({\hat{\mu}}_{\mathrm{t}}\right) $$ moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable

A FB

1

$$ {A}_{\mathrm{FB}}^{(1)} $$ is used to approximate the asymmetry. Candidate

t

t ¯

$$ \mathrm{t}\overline{\mathrm{t}} $$ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for

t

t ¯

$$ \mathrm{t}\overline{\mathrm{t}} $$ final states. The values found for the parameters are

A FB

1

=

0.048

− 0.087

+ 0.095

stat

− 0.029

+ 0.020

syst

,

μ ̂

t

= −

0.024

− 0.009

+ 0.013

stat

− 0.011

+ 0.016

syst

,

$$ {A}_{\mathrm{FB}}^{(1)}={0.048}_{-0.087}^{+0.095}{\left(\mathrm{stat}\right)}_{-0.029}^{+0.020}\left(\mathrm{syst}\right),{\hat{\mu}}_{\mathrm{t}}=-{0.024}_{-0.009}^{+0.013}{\left(\mathrm{stat}\right)}_{-0.011}^{+0.016}\left(\mathrm{syst}\right), $$ and a limit is placed on the magnitude of

d ̂

t

$$ \left|{\hat{d}}_{\mathrm{t}}\right| $$ < 0.03 at 95% confidence level.