A template method to measure the $t\bar{t}$ polarisation

Abstract

We develop a template method for the measurement of the polarisation of $t\bar{t}$ pairs produced in hadron collisions. The method would allow to extract the individual fractions of $t_L{\bar{t}}_L$, $t_R{\bar{t}}_R$, $t_L{\bar{t}}_R$ and $t_R{\bar{t}}_L$ pairs with a fit to data, where $L,R$ refer to the polarisation along any axis. These polarisation fractions have not been independently measured at present. Secondarily, the method also provides the net polarisation of $t$ and $\bar{t}$, as well as their spin correlation for arbitrary axes.

Comments: LaTeX 9 pages. Minor changes and some extra discussions, final version in EPJC