Attractive versus repulsive gravity between fundamental particles

Determine whether gravitational interactions between Standard Model fundamental particles are always attractive or can be repulsive, specifically for quark–antiquark and lepton–antilepton pairs, given that current ALPHA-g antihydrogen measurements do not resolve this question.

Background

The author distinguishes between fundamental particles (quarks and leptons) and composite bound states (such as protons and antiprotons). While ALPHA-g confirms attraction between matter and antimatter at the atomic/nuclear scale, it does not directly inform the nature of gravitational interactions at the level of individual fundamental particles.

This leaves unresolved whether gravity between specific particle–antiparticle pairs might be repulsive, a question that requires more precise or different experimental probes than those currently available.