82
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Why is matter-antimatter asymmetry surprising, if asymmetry can be generated by a random walk in which particles go into black holes?
Congratulations on finding a method for baryogenesis that works! Indeed, it's true that if you have a bunch of black holes, then by random chance you'll get an imbalance. And this imbalance will ...
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34
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Why is matter-antimatter asymmetry surprising, if asymmetry can be generated by a random walk in which particles go into black holes?
Locality
The random walk would be expected to create different (opposing) asymetries in different regions, including regions that are distant enough to not affect each other. If this would be the ...
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14
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If all the Structure in our visible Universe originated from Quantum Fluctuations, why isn't there as much Anti-Matter as Matter?
The matter-antimatter asymmetry requires the three Sakharov conditions to be satisfied. I'll summarise that link's explanation. Unfortunately, your question isn't completely solved.
The first ...
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7
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How would we tell antimatter galaxies apart?
I concur with Count Iblis's answer that if we would detect an uptick in anti-neutrinos when a supernova occurs within said galaxy.
To understand this, let's take the case of what happens in our ...
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7
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Why is baryon number conservation an accidental symmetry
I think your misunderstanding is precisely that you think that $U(1)$ gauge symmetry in SM can be associated to any quantum number such as baryon or lepton number. No, it can not. The $U(1)$ coming ...
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6
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Why are both C and CP violation necessary for baryogenesis?
Assume You have only $C$-violation. Then it implies that the rate $\Gamma$ of hypothetical process $p^{-} \to e^{-}\gamma$ won't be equal to the rate of hypothetical process $p^{+} \to e^{+}\gamma$, ...
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6
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Can someone clarify this quote about weak interactions causing neutron-to-proton ratio to go to zero if equilibrium were possible?
The mention of the weak force is something of a red herring as any interaction that allows protons and neutrons to interconvert would give the same result.
Earlier in the chapter the authors describe ...
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5
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How does inflation get rid of initial Baryon asymmetry (if any)?
The comment on the review you indicated can be explained in the following way. Inflation is a period of nearly exponential expansion of the Universe that is required to solve the flatness problem, the ...
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5
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Does Leptogenesis require lepton number violating vertices?
Short answer (we're hung up on terminology):
If you use the word "Leptogenesis" exclusively for theories with lepton violating vertices, then "Dirac Leptogenesis" is a misnomer.
If you use the word "...
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5
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Why is matter-antimatter asymmetry surprising, if asymmetry can be generated by a random walk in which particles go into black holes?
Matter and antimatter isn't created one at a time at random. To fix your simulation, you'd need to always create an electron at the same time you create a positron.
Does adding a black hole break ...
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5
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How do we know that distant galaxies are not made up of antimatter primarily?
Space isn't a perfect vacuum. Intergalactic matter has very low density, but there is a lot of it. If some galaxies were antimatter, in theory gamma ray astronomers would see matter-antimatter ...
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4
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Is proton decay considered in neutron star models (and LHC)?
One has to clarify the meaning of "decay" as far as protons go.Here is a proton decay diagram in GUTS:
Notice that what is really disappearing is two quarks going into an antidown and an e+, to get ...
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3
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Baryon asymmetry still going on
Baryon number violation, one of the requirements for baryon asymmetry, only occurs at any significant rate in the Standard Model at high temperatures, much higher than are known to exist in the ...
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3
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Why does matter-antimatter asymmetry only refer to baryon asymmetry?
People do consider the lepton asymmetry, it plays an important role in Leptogenesis. This is the idea that the baryon asymmetry was "born" as a lepton asymmetry, which was transferred to the baryon ...
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3
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Difference between "C-violation without CP-violation" and "C-violation with CP -violation"
Let's look at the expression for the differential decay rate of $X\to f$, where $f$ contains an arbitrary number of particles with momenta $\mathbf p_i$ and spin $s_i$. This is given by: $$2m_X \text ...
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3
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Understanding the fine-tuning problem related to baryon asymmetry as an initial condition
To start, it is important to notice that a statement like "For each x antiquarks, there are x+1 quarks" is vacuous unless you specify the instant at which you are looking at the system. To give an ...
- 1,306
3
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Understanding the fine-tuning problem related to baryon asymmetry as an initial condition
The calculation is actually reasonably simple. Most of the photons in the Universe are CMB photons, and the number density of CMB photons has been measured to exquisite accuracy. There are about $N_\...
- 18.6k
3
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Chemical equilibrium for a $2-2$ scattering and Boltzmann equation in cosmology and astroparticle physics
The first term on the right hand side should have a minus sign because the process $A+B \rightarrow C +D$ depletes the species $A$. So if all the $f$'s have their equilibrium form, $dn/dt$ should be ...
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3
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Could there be a region of the universe that is dominated by antimatter?
If there were any regions in the observable universe where antimatter was more abundant than matter then we would be able to observe the gamma radiation produced by the annihilation of matter and ...
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3
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Could the matter-antimatter symmetry be local rather than universal?
I touched on this in an answer I wrote in the Astronomy SE. The brief answer is there's no theoretical reason why it can't be local, but it's observationally excluded:
At some level the idea that ...
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2
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Theta Vacuum of Yang-Mills theory and Baryon number violation
There is a definite fermion number only before and after the transition, as one can see from your equation for divergence of baryon current. Analogously, the system is in the definite vacuum state ...
- 1,996
2
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Is this article about the SMASH hypothesis a fair assessment?
It is really not totally a new hypothesis. They are taking some model extensions to the SM that were proposed in other papers to add Beyond the SM particles that would account for inflation, ...
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2
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How do sufficiently energetic photons form electrons-positron pairs?
Pair production is not something where the rule is 'go see what Wikipedia says'. Wikipedia just tries to summarize what is known, sometimes well, sometimes not.
Pair production is a well understood ...
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2
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fate of a hadron in a big rip
Answering what I believe to be your implicit question:
There has been considerable speculation (particularly in the lay community) that at the point where the Big Rip / Dark Energy becomes relevant ...
2
votes
Is proton decay considered in neutron star models (and LHC)?
Both M82-X2 and the new object referred to in the new edit are examples of ultraluminous X-ray sources, with luminosities exceeding the Eddington luminosity by 100-1000 times (if the flux is assumed ...
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2
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How can we assert $\mathrm{ matter } / \mathrm{ antimatter } \gg 1$ further than $locally$?
Is the spectrum of matter and antimatter different?
It is in interactions that one can know whether some celestial object is made of matter as the earth or of antimatter. When matter meets antimatter ...
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