Crafting polarizations for top, W , and Z

Abstract

We put forward a method to tune the polarization state of decaying heavy particles (top quarks and $W/Z$ bosons) in a preexisting Monte Carlo sample. With this technique, dubbed as ``custom angle replacement,'' the decay angular distributions are modified in such a way that the desired polarization state is reproduced, while the production kinematics are unchanged. A nontrivial test of this approach is presented for the top quark semileptonic decay $t\ensuremath{\rightarrow}Wb\ensuremath{\rightarrow}\ensuremath{\ell}\ensuremath{\nu}b$, with $\ensuremath{\ell}=e$, $\ensuremath{\mu}$, in which the decay distribution is four-dimensional and involves three different Lorentz frames. The proposed method can be used to obtain event samples with polarized heavy particles, as required by experimental measurements of polarization and spin correlations.