Impact of CLAS and COMPASS data on polarized parton densities and higher twist

We have reanalyzed the world data on inclusive polarized deep inelastic scattering (DIS) including the very precise CLAS proton and deuteron data, as well as the latest COMPASS data on the asymmetry A₁^d, and have studied the impact of these data on polarized parton densities and higher twist effects. We demonstrate that the low Q² CLAS data improve essentially our knowledge of higher twist corrections to the spin structure function g₁, while the large Q² COMPASS data influence mainly the strange quark density. In our new analysis we find that a negative polarized gluon density, or one that changes sign as a function of x, cannot be ruled out on the basis of the present DIS data.