I Could the primeval antimatter "be among us"?

[Gerinski]

Kindly allow a me to post this layman question. In popular science it is often stated that the very early universe should have produced approximately equal amounts of particles and antiparticles, and that the dominance of matter over antimatter in the current universe is somehow a mystery. They often point that a particle and its antiparticle should have annihilated releasing EM radiation as a result.

My question is, particles did not necessarily have to meet their antiparticle, and in that case they needed not annihilate but could form other composite particles with different fate than annihilation.

For example mesons are made up of a quark and an antiquark. They are not stable in our current low energy universe, but they might have survived some time in the energetic early universe. If I'm not misinformed they eventually decay into electrons, neutrinos and photons. So this is an example where initial matter + antimatter could have combined into actual particles and decayed into particles which are common today, without suffering matter-antimatter annihilation.

I have more doubts regarding baryons, this website states that "the neutron contains more quarks than anti-quarks, whereas the anti-neutron contains more anti-quarks than quarks." I doubt that this is correct, but if it was it could also explain where antiquarks went to, into our everyday protons and neutrons.

https://profmattstrassler.com/artic...e-technical-concepts/what-are-anti-particles/

At any rate the question is, is it not possible that primeval antimatter instead of meeting their antiparticles and annihilating did combine with other particles (some of the results eventually decaying) forming our familiar universe?

Thanks!

 

[phinds]

At any rate the question is, is it not possible that primeval antimatter instead of meeting their antiparticles and annihilating did combine with other particles (some of the results eventually decaying) forming our familiar universe?

No.

https://www.physicsforums.com/threads/have-we-observed-antimatter-in-the-early-universe.868129/

 

[mfb]

So this is an example where initial matter + antimatter could have combined into actual particles and decayed into particles which are common today, without suffering matter-antimatter annihilation.

It is not called annihilation, but the result is the same - both quark and antiquark are gone.

I have more doubts regarding baryons, this website states that "the neutron contains more quarks than anti-quarks, whereas the anti-neutron contains more anti-quarks than quarks."

It is correct, and it is exactly the asymmetry we see today: protons and neutrons, but (nearly) no antiprotons and antineutrons.

At any rate the question is, is it not possible that primeval antimatter instead of meeting their antiparticles and annihilating did combine with other particles (some of the results eventually decaying) forming our familiar universe?

No.

 

[nikkkom]

In Standard Model, quark and lepton sectors are independent (there is no interaction which turns a quark into lepton(s)), and therefore labels for "matter" and "antimatter" can be assigned independently, and *differently*, in these sectors.

IOW: you may well decide to label electrons to be "antimatter" and positrons "matter". In such a picture, our Universe does contain a lot of antimatter (in the form of electrons).

While you are working in SM, this labeling is only a convention. If we'd ever arrive at a general consensus of a BSM theory linking quarks and leptons, it may well turn out that electrons really *are* antimatter.