1. Single Top Polarization using Madevent and ONETOP samples
The polarization of single top quarks generated by Madevent was analysed. I looked at the t- as well as the s- production channel.
For the t-channel the spin correlation distributions are as expected, but the s-channel distribution in the optimal basis doesn’t show the expected full polarization. Therefore I compared my results with two Tevatron data sets, one set generated by Madevent, the other one a leading order calculation with the ONETOP generator.
This comparison leads to the presumption that Madevent cannot generate the polarization of s-channel produced single top quarks correctly.
The application of cuts lead to the expected impact on the shape of the spin correlation distributions.
Added March 19th: We are not sure any more if it is really Madevent that makes the mistake, maybe the ONETOP code has an error in it.
Added April 11th: Either my macro or Madevent are wrong as full polarization is theoretically expected (see PolarizationMadevent).
Added May 7th: It is Madevent! I will update PolarizationMadevent.
2. Looking for Single Top Polarization in Atlas samples