Contributions of stochastic background fields to the shear and bulk viscosities of the gluon plasma

The contributions of confining as well as nonconfining nonperturbative self-interactions of stochastic background fields to the shear and bulk viscosities of the gluon plasma in SU(3) Yang-Mills theory are calculated. The nonconfining self-interactions change (specifically, diminish) the values of the shear and bulk viscosities by 15%, that is close to the 17% which the strength of the nonconfining self-interactions amounts of the full strength of nonperturbative self-interactions. The ratios to the entropy density of the obtained nonperturbative contributions to the shear and bulk viscosities are compared with the results of perturbation theory and the predictions of {\cal N}=4 SYM.