It is an unsolved problem. My suspicion is on inflation; it could have "killed" antimatter!

Inflation cannot kill anti matter, it can only inflate 3D space, which affects both matter and antimatter densities. It is generally thought that there existed a slight dis-balance in the number densities of matter and antimatter when radiation decoupled (nb ~ nb_bar ~n_gamma). This is much after the end of inflationary era. Matter and antimatter annihilated each other and formed radiation. What we see is that slight dis-balance in primordial number densities. Presently baryon to photon ratio of number densities is 5.0-7.0 x 10-10 approx. Models of baryogenesis and leptogenesis try to explain this ratio.

Ref: http://arxiv.org/abs/hep-ph/9901362

@ Biswajoy

I had just made a wild guess. thanks for correcting me. But if antimatter was produced before CMM photons were released, does it imply that radiation density due to increased matter and antimatter annihilation was much higher. And how can you deny the possibility that pair production did not happened from the radiation to restore the matter and antimatter?

Riyaz: let's assume a few possibilities. If matter is created from energy, matter-antimatter pairs are produced. If these pairs mix up, most of them will annihilate.

Will anti-neutrons and anti-protons group with positrons? Based upon which laws?

If they do, why would they be flying away from the normal matter? If they don't, why don't we see them around us?

Let's take another input now. I have proven that elementary matter is a vector and that an electron-positron pair has opposite mass vectors, so that it mostly attracts a big object, but will slightly repell each other gravitationally two by two.

See https://www.researchgate.net/post/Is_antimatter_attracted_by_gravity_or_repelled_How_do_we_know_or_how_will_we_discover_an_answer_Why_is_this_important/2

Hence, in this case, when the matter-antimatter pairs are produced, will the picture change? The more parallel the particles' mass vector are, the more they will attract gravitationally, and vice versa. That could explain an universe with a global gradient of mass vector orientations going gradually from 0° to 360° in all directions.

Our own actual part of the universe would have all mass vectors oriented nearly alike.

This approach even can explain the superlarge cluster structures, which are structured in filaments and so...

@ Vikash,  Inside primordial plasma due to thermal thermal equilibrium nb ~ nbbar ~ ngamma. As baryons annihilate pairwise yielding one photon per pair, photon density changes by a factor of two.

Riyaz,

Your question can be answered by assuming absolute potential wirth a floating ground potential. When we realise how potential is absolute it leads to the understanding that ground potential must lie somewhere between zero potential and absolute maximum potential. 

As it happened I was able to find the equation showing the relationship between the electron mass and the proton mass and in doing so we also get the correct value for ground potential.

So the answer to your question is that nothing is missing, matter and anti matter exists in equal amounts but you as observer are seeing a highly assymmetric version of reality.

Research Ground Potential

I remember the symmetric matter-antimatter cosmological model which was very popular in the seventies of the last century. In this model, matter and antimatter where created in the same proportion at a early stage and in hot equilibrium against creation-annihilation processes. It was shown that the equilibrium of this plasma was broken by the effect of expansion, which induces a phase transition towards the clustering of matter and antimatter in separate lumps, as in an oil-vinegar sauce. Initially, once the lumps are formed, the annihilation processes take place on their contact surfaces, generating strong radiative pressures that contribute to the expansion. Next, the lumps move away, lost their contact, expand and structure, giving rise to separate regions of the Universe consisting of clusters of galaxies make up of matter or antimatter.

In the following theory, the universe begins with particles called Savitons which are associated with elcctronuclear force which came into existence just after the gravity separated at Planck time. These particles are bosonic spin 1 particles similar to photons and does not carry any mass or charge. Their energy is of the order of planck energy. They are produced in pairs of particles and anti-particles. Just like photon, saviton is its own anti-partcle. So the only difference between the two is the direction of its momentum. All the rest of the particles emerge out of these savitons when they collide with each other and slow down from speed of light to lower velocities and some of their own energy gets converted into mass and charge. The particles that develop opposite charge are a very small fraction (perhaps only 4%) of the total number of savitons produced at planck time. These charged particles are distinguished in this theory by the name matter and anti-matter. And most of the anti-matter fermions are used up in creating matter hadrons and mesons. This is why most of our visible universe is matter dominated. This is also consistent with ALICE experiment on symmetry in nature.

http://phys.org/news/2015-09-fundamental-symmetry-nature.html

Article Periodic quantum gravity and cosmology

In fact, we can imagine a "natural" scenario in which the antimatter and matter are present in equal amounts on large scale. When we linearize the general relativity, we obtain a theory very similar to the Maxwell's idealization of electromagnetism.

By this way, with the bold assumption that the antimatter is negative gravitational mass (but always positive inertial mass), we are in an idealization where the particles of opposite charge (mass) repel themselves (and same charge attract themselves).

This solution leads necessarily to an early inflation and a structure of several universes of homogeneous gravitational mass, alternatively positive and negative. Furthermore, this explanation could explain the dark energy.

Last year, I published a paper on this idealization (https://hal.archives-ouvertes.fr/ensl-01122689v1) that explains all of this.

https://hal.archives-ouvertes.fr/ensl-01122689v1

“Can matter and antimatter be present in equal amounts on large scale structure of the universe?”

- for such suggestion seems there are no some experimental hints. Though indeed material objects – first of all – fundamental and sub-atomic particles, exist mostly as two types – particles and antiparticles. That is because of every material object [and everything else, though] is some informational structure, including the particles are some logical cyclic algorithms [that are uninterruptedly run] also.

It was shown rather long time ago that some changes/transformations of the information proceeds without (or, at least with smallest) dissipation of the energy, if these transformation are logically reversible. Correspondingly particles in Matter are reversible cyclic algorithms and interactions between particles proceeds as exchange by some reversible information also; in physics this fact is realized as the energy conservation law.

Thus particles by convention are some algorithms with “direct commands orders”, the antiparticles are “the same algorithms”, but with opposite orders.

However the difference appears if an algorithm [of a particle] isn’t symmetrical, what seems appears, first of all, because of the particles’ charges (electrical, colour, strangeness…) algorithms are asymmetrical – in contrast to “neutral” particles, for example – photons.

To realize reversible algorithms (i.e. a reversible order of changes of internal states of particles) in Matter the special dimension exist – “the coordinate time dimension”, the fours coordinate of the Matter’s absolute [5]4D Euclidian spacetime, and particles that have “rest masses” move in this time in positive direction, when antiparticles move in the negative temporal direction.

The neutral particles move in 3D spatial directions only (photons) or can be at “temporal rest”, when their constituents move in +/- temporal directionssimultaneously – for example quark and antiquark in a pi-0 meson.

Among the charges that define properties of particles there exist the unique charge, which is totally symmetrical – that is the gravitational charge. Just therefore particles and antiparticles gravitationally interact identically, independently on what interact – pairs “a particle and a particle”, “an antiparticle and an antiparticle”, “a particle and an antiparticle”.

If a cyclic algorithm is realized with some “charged sections”, that seems as some gyroscope, which has a certain rotation rate direction. But if some algorithm is totally symmetrical, then its rotation rate’s direction is uncertain and so it is logically permissible to conclude that all such gyroscopes have the same direction of the rotation rates; thus all such particles can be all only particles or only antiparticles [what is inessential in the problem – so from what particles is Matter made?].

Thus if at Matter’s Beginning the primary particles were “totally neutral” – i.e. having only the gravitational charge, then at once Matter was constituted from these “particles” only and without “antiparticles”; further the interactions of the primary particles resulted in the existent bouquet – baryons, electrons, neutrinos, etc. appearance.

See also the SS post in the thread https://www.researchgate.net/post/Is_antimatter_attracted_by_gravity_or_repelled_How_do_we_know_or_how_will_we_discover_an_answer_Why_is_this_important

on 5-th page and the link in this post.

Cheers

“…Depends on what you mean by large scale…Also baryon number is not conserved in the Standard Model of particle Physics…”

- that seem as not too convincing arguments. The practical absence of antimatter “inside observable horizon” seems as rather probably true fact; when this horizon is evidently rather large – thus it seems reasonable that if at Beginning practically equal qualities of the matter and the antimatter were created [now always corresponding pairs appears practically in the same spatial point], then seems as practically improbable some corresponding partial density fluctuations when these both Matter’s constituents could appear be so separated in so large and so distant space regions.

Besides – it seems rather plausible also that this [experimentally detected] non-conversation at decays of rather exotic particles doesn’t mean something fundamental – simply some exotic particles’ algorithms in direct and opposite commands’ order directions [see the SS post on the first page] aren’t totally asymmetrical. And what?

Cheers