It has been found in CERN (see this ) that matter and antimatter atoms have no differences in the energies of their excited states. This is predicted by CPT symmetry. Notice however that CP and T can be separately broken and that this is indeed the case. Kaon is classical example of this in particle physics. Neutral kaon and anti-kaon behave slightly differently.
This finding forces to repeat an old question. Where does the antimatter reside? Or does it exist at all?
GUTs predicted that baryon and lepton number are not conserved separately and suggested a solution to the empirical absence of antimatter. GUTs have been however dead for years and there is actually no proposal for the solution of matter-antimatter asymmetry in the framework of mainstream theories (actually there are no mainstream theories after the death of superstring theories which also assumed GUTs as low energy limits!).
In TGD framework many-sheeted space-time suggests possible solution to the problem. Matter and antimatter are at different space-time sheets. One possibility is that antimatter corresponds to dark matter in TGD sense that is a phase with heff=n× h, n=1,2,3,... such that the value of n for antimatter is different from that for visible matter. Matter and antimatter would not have direct interactions and would interact only via classical fields or by emission of say photons by matter (antimatter) suffering a phase transition changing the value of heff before absorbtion by antimatter (matter). This could be rather rare process. Bio-photons could be produced from dark photons by this process and this is assumed in TGD based model of living matter.
What the value of n for ordinary visible matter could be? The naive guess is that it is n=1, the smallest possible value. Randell Mills has however claimed the existence of scaled down hydrogen atoms - Mills calls them hydrinos - with ground state binding energy considerably higher than for hydrogen atom. The experimental support for the claim is published in respected journals and the company of Mills is developing a new energy technology based on the energy liberated in the transition to hydrino state.
These findings can be understood in TGD framework if one has actually n=6 for visible atoms and n=1, 2, or 3 for hydrinos. Hydrino states would be stabilized in the presence of some catalysts. See this.
The model suggests a universal catalyst action. Among other things catalyst action requires that reacting molecule gets energy to overcome the potential barrier making reaction very slow. If an atom - say (dark) hydrogen - in catalyst suffers a phase transition to hydrino (hydrogen with smaller value of heff/h), it liberates binding energy, and if one of the reactant molecules receives it it can overcome the barrier. After the reaction the energy can be sent back and catalyst hydrino returns to the ordinary hydrogen state. The condition that the dark binding energy is above the thermal energy gives a condition on the value of heff/h=n as n≤ 32. The size scale of the dark largest allowed dark atom would be about 100 nm, 10 times the thickness of the cell membrane.
The notion of phosphate high energy bond is somewhat mysterious concept and manifests as the ability provide energy in ATP to ADP transition. There are claims that there is no such bond. I have spent considerable amount of time to ponder this problem. Could phosphate contain (dark) hydrogen atom able to go to the hydrino state (state with smaller value of heff/h) and liberate the binding energy? Could the decay ATP to ADP produce the original possibly dark hydrogen? Metabolic energy would be needed to kick it back to ordinary bond in ATP.
So: could it be that one has n=6 for stable matter and n is different from this for stable antimatter? Could the small CP breaking cause this?
For background see the chapter Classical TGD.