S. Groote et al., Gluon polarization in e(+)e(-)-> t(t)over-bar-G: polar angle dependence and beam polarization effects, EUR PHY J C, 7(1), 1999, pp. 49-59
We calculate the linear and circular polarization of gluons produced in con
junction with massive quarks in the annihilation process e(+)e(-) --> q(q)o
ver-bar-G. The linear polarization is calculated in the hadron event plane
as well as in the gluon-beam plane. Beam polarization and polar orientation
effects are included in our discussion. For typical top pair production en
ergies at the Next-Linear-Collider (NLC) the degree of linear polarization
in the hadron event plane remains close to its soft gluon value of 100% ove
r most of the energy spectrum of the gluon. The linear polarization in the
gluon-beam plane is generally smaller but peaks toward the hard end of the
gluon spectrum. The dependence of the linear polarization on beam polarizat
ion and on the polar orientation of the gluon is small. The circular polari
zation is largest for maximal gluon energies and shows a strong dependence
on the longitudinal beam polarization. The longitudinal polarization of the
beam may therefore be used to tune the circular polarization of the gluon.
The massive quark results are compared with the corresponding results for
the massless quark case.