Can bosons have anti-particles? In the past, I would have answered this question with a yes, primarily because I can imagine writing down a QFT for complex scalars that has a $U(1)$ symmetry that allows me to assign a conserved charge. That is, I expect to obtain a charged spin-0 boson with an additive quantum number. A $CP$-transformation would change these quantum numbers into their negatives and I would consider the corresponding particle an anti-particle.
Of course I know at the same time that Standard Model particles, such as the $Z$-boson and the Higgs boson, are considered not to have observable anti-particles (in the way that electrons have, for instance). On the other hand, mesons are considered (composite) bosons and are known to have anti-particles. I used to take the viewpoint that the mentioned elementary bosons are their own anti-particles, because they are charge-neutral.
After reading, by chance, an interview with Geoff Taylor (Melbourne) I am a bit confused, however. He says that bosons can not have anti-particles, because this property is restricted to Fermions and explicitly refutes the idea that they are their own anti-particles:
"Really fermions are the things where we have this idea of a particle and anti-particle pair," says Taylor, "anti-particles at the fundamental level are fermions with the opposite charge."
"The $W+$ and $W-$ bosons only differ by charge so it's an easy mistake to talk about it that way [as particle and anti-particle], but it's just a pair of different charges."
"While they behave in some sense like particle and anti-particle, we don't think of one as the anti-particle counterpart of the other because they're force carriers," says Taylor
"Fermions have conservation laws associated with them, so for example they are created in particle-anti-particle pairs, the sum of their quantum numbers cancelling to maintain the conservation laws," explains Taylor.
"Bosons operate under different laws and can be created singly. This is a crucial distinction and is in nature of being either matter particles or force carriers."
(It should perhaps be mentioned that he works in experimental HEP-data analysis and not theory, but still he could know more.)
Which, if any, of these viewpoints is correct?