Title:What Exactly is Antimatter (Gravitationally Speaking)? A Second Scenario

Abstract:In arXiv:2401.10954 I investigated the consequences of regarding the mass-energy of the fundamental fermions (quarks and leptons) and the Intermediate Vector Bosons (e.g., photon) as matter, and the fundamental antifermions (antiquarks and antileptons) as antimatter within the context of an antigravity universe, one where matter and antimatter repel gravitationally. Here I consider an alternative scenario in which the Intermediate Vector Bosons, which are neither particle nor antiparticle, are gravitationally attracted to both fundamental fermions and antifermions. This leads to a prediction for the free-fall acceleration of antihydrogen of $a_{\bar{H}}=(0.78^{+0.11}_{-0.08})g$ as well as quite different expectations for the free-fall accelerations of the $\mu^+$ and positronium from those derived in the previous article. The cosmology which results from the premise presented here is little different from the standard cosmology (i.e., the $\Lambda$CDM model). One significant deviation is that there would be an increased accelerated expansion in the early moments after the Big Bang due to the gravitational repulsion between the fundamental fermions and antifermions.