Spin output

In order to enable spin output, two conditions have to be fulfilled:

1. Spin interactions have to be enabled in the collision term section of the configuration file.
2. The spin components spin0, spinx, spiny and spinz have to be specified in the Quantities list of the Particles output subsection. See user guide description for more information.

Spin output is available in OSCAR2013 format. If spins are enabled, the resulting output file contains the four components of the mean spin (Pauli-Lubanski) vector \(S^\mu\). The components of the mean spin vector are set in two different ways, depending on the mode, in which SMASH is used:

SMASH Collider Modus

In the collider mode, the components of the mean spin vector are sampled from a gaussian distribution with a mean value of 0 in the particle rest frame to ensure that the average polarization vanishes. This strategy guarantees that spectators do not contribute with an artificial polarization.

SMASH List Mode

In the list mode, the components of the mean spin vector are read from the input file.