Top-quark spin properties at LHC

Abstract

Due to its high mass top quarks decay before top-flavoured hadrons can be formed. This feature yields experimental access to the top quark polarization and production asymmetries. The large top quark sample moreover enables measurements of other properties, such as the W-boson branching ratios and helicity, and fragmentation functions of the bottom quarks. In this contribution, recent measurements of top-quark spin properties at the LHC are presented, including in particular the first evidence of the charge asymmetry in $t\bar{t}$ production (ATLAS), the charge asymmetry in a boosted regime (CMS) and the first measurement of the charge asymmetry in $t\bar{t}+W$ (ATLAS).