I hope this question isn't naive or anything of the sort but I am relatively new to this topic and this is the first question I ask on here. The Collins asymmetry which is exclusively a quark-fragmentation phenomena and explicitly doesn't deal with gluons.
Roughly speaking, the Collins asymmetry can be thought of as:$$ A \sim \frac{N^{\uparrow} - N^{\downarrow}}{N^{\uparrow} + N^{\downarrow}} $$ where the numerator has the polarized piece (the quark specific phenomena because of transversity) and the denominator is the unpolarized piece (both the quarks and gluons). Thus, why don't gluons have transversity? I assume this is applicable to all Bosons?
I appreciate the help!
