Negative gravitational charge of antiquarks

Determine whether antiquarks possess a negative gravitational charge (opposite in sign to the gravitational charge of quarks), and ascertain whether this effect is currently obscured by the composite structure of antiprotons and by the limited precision of the ALPHA-g antihydrogen free-fall measurements (presently at about 20% of g).

Background

ALPHA-g has established that antihydrogen falls downward, but the present precision leaves open the possibility that its acceleration may be slightly lower than that of ordinary matter. The author discusses how composite particles like protons and antiprotons contain both matter and antimatter contributions, which could mask fundamental differences in gravitational charge at the quark level.

If antiquarks carry a negative gravitational charge, an antiproton’s net gravitational charge would be reduced relative to a proton, potentially leading to ḡ < g for antihydrogen. Given current experimental precision and the composite nature of antiprotons, the presence of a negative gravitational charge for antiquarks could be obscured, motivating higher-precision tests.