Questions tagged [baryogenesis]

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Could the matter-antimatter symmetry be local rather than universal?

In the observable universe there is an antimatter-matter asymmetry. Are there any theories that propose that this is just a local asymmetry one fluctuation in a universe with an overall symmetry?
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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?

I'm self-studying Modern Cosmology by Dodelson and Schmidt 2nd edition, and I've found a certain passage in Section 4.2.1 particularly interesting. It says, Therefore, at high temperatures, there ...
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Trying (and failing) to calculate baryon/photon ratio

I'm reading through Modern Cosmology by Dodelson and Schmidt 2nd edition on my own, and at the start of Section 4.2 the book says that we can compute the baryon/photon ratio at the time of big bang ...
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What are the conditions needed for baryogenesis? [duplicate]

Physicists have created antimatter in the laboratory. But when they do, they create an equal amount of matter. That suggests that the Big Bang must have created matter and antimatter in equal ...
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Vacuum Degeneracy of the Standard Model

There are infinite vacua, which are degenerate, in Standard Model (people know this in the context of Sphaleron, Instanton and so on). I'd like to know why there are infinite vacua. I'm glad to ...
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What is the value of the baryon asymmetry? [duplicate]

Define the baryon asymmetry, which sometimes is called the baryon density, as the baryons to photons ratio $\eta = n_b/n_\gamma$. I found in Ref. 1, published in 2018, that the value of $\eta$ is of ...
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About the recent bounds on the baryon asymmetry

While I'm studying the baryon asymmetry, the ratio of baryons number to the photons number in the universe - some times is called baryon density - $: \eta= n_b/n_\gamma$ I have found many experimental ...
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Does time symmetry cause the matter/antimatter asymmetry?

It’s known that the fundamental laws of physics are time symmetric. In electromagnetism $t$ can be changed to $-t$ and time reversal is also valid in particle physics, as there is the CPT symmetry. ...
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B-L violation and Sakharov's first condition

The most common version of Sakharov's first condition that I see is "Baryon number violation." Of course this makes sense because without baryon number violation, you can't start out with a ...
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Charged black holes and the matter antimatter imbalance

After the big bang, could it be that lots of charged primordial black holes began to form? Would this make it more likely for oppositely charged particles to fall in, and thus cause the matter/...
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Can one-electron world theory be revived if the Sakharov's conditions are completely met?

Regarding that people object about the matter antimatter balance in the one-electron world theory to discard it, can it be once more revived if the Sakharov's conditions are met so that the matter ...
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Amount CP violation needed

It is widely known that the CP violation provided by the Standard Model ( SM )is insufficient to explain the baryon asymmetry that we observe. However, I never came across any quantitative ...
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Big bang should have made up an equal amounts of both matter and anti matter, then why don't we see such?

So, my question arises that how do we know that normal matter is more in quantity or number than anti-matter? Research at ALPHA said that anti-matter that the spectrum of hydrogen and anti-hydrogen ...
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Positrons in space, are they remnants of baryon asymmetry?

This recent paper By observing 1.9 million positrons (out of 107 billion cosmic rays), the AMS Collaboration finds that the energy dependence of the positron flux is very complex. ... Overall, the ...
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How come positrons don't destroy all the electrons in the universe?

What it says on the title. How come all the positrons don't destroy all the electrons in the universe and vice versa? They are attracted to each other due to opposing charges.
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Could it be that at the big bang equal amounts of matter and antimatter were created, but the antimatter got stuck in black holes? [duplicate]

I recently watched PBS spacetime's video series on the black hole information paradox. Where they first discussed the no hair conjecture and then later also the true destruction of information by ...
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Could there be a region of the universe that is dominated by antimatter?

I was reading some texts explaining that since our region of the world is overwhelmingly dominated by matter, and not by anti-particles, this suggests that in some region of the universe, there will ...
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Why is there matter when all of it should have annihilated with antimatter?

The theory is that after the Big Bang, photons turned into matter and antimatter particle pairs, but they should have all annihilated with each other. Since there would be an equal amount of matter ...
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How does the baryon asymmetry control temperature fluctuations of CMB?

The temperature fluctuations of the Cosmic Microwave Background (CMB) have a sensitive dependence on the quantity of baryon asymmetry of the universe. In fact, analysis of CMB fluctuations is one of ...
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Why more matter than antimatter and if so, how do we know this?

firstly, how do we know this? and secondly, would it not be possible that either antimatter and matter were produced in separate regions or randomly and if randomly it makes sense that in any given ...
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Experimental evidence of interaction out of thermal euilibrium?

Sakharov gave three conditions for the matter-antimatter asymmetry observed in the universe. (1) Baryon number violation: Don’t have any experimental confirmation yet. (2) C-symmetry and CP-symmetry ...
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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?

My understanding is the early universe was a very "hot" (ie energy dense) environment. It was even hot enough for black holes to form from photons. My second point of understanding is that black ...
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What if there were only 1 generation of fermions?

The number of fermion generations has many effects beyond the mere existence of "3 copies of fermions," including determining scatterings, constraining CP violation, influencing electroweak symmetry ...
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Why is baryon number conservation an accidental symmetry

I have to write a report surrounding the subject of baryogenesis and I wanted to start this report off with explaining how the first Sakharov condition: Baryon number violation is possible within the ...
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How does the CMB constrain the baryon asymmetry?

The CMB contains information about baryon acoustic oscillations in which baryons (I assume protons and electrons) and photons form a plasma exhibiting sound waves. How is information about the baryon ...
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Where is all the Antimatter?

This is obviously a duplicate of If matter and antimatter... However, it's now four to five years after a swarm of videos were made on this subject. At the time, there was a consensus that the LHC ...
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Chemical equilibrium for a $2-2$ scattering and Boltzmann equation in cosmology and astroparticle physics

Definition of chemical equilibrium According to the definition of chemical equilibrium in Wikipedia, it is a situation where the rate of the forward reaction is same as the rate of backward reaction ...
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Can the CKM matrix supply the CP asymmetry as required by baryogenesis, in principle?

In the process of Baryogenesis through Leptogenesis from the decay of heavy Majorana neutrinos, the necessary CP violation is perhaps provided only by the CP phases in the PMNS matrix. But the Weak ...
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Is the inflaton field baryon symmetric?

The theory states that after inflation ends, the energy stored in the inflaton field decays to produce particles. Does the inflaton field have baryon number associated with it? Is the field baryon ...
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Could matter in the universe come from some process other than the decay of inflaton field?

Could matter in the universe come from some process other than the decay of inflaton field? Do we have any theoretical reasons that support the idea that matter was created from the decay of ...
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Baryon asymmetry still going on

I read these questions and answers and it made me curious. Baryon asymmetry Why do we believe baryon asymmetry? Why does matter-antimatter asymmetry only refer to baryon asymmetry? How does ...
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4 votes
2 answers
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Why abundance of matter requires fundamental asymmetry - cannot be statistical symmetry breaking?

There are rather no doubts that there is more matter than antimatter in our Universe, it is usually assumed that it was created during short baryogenesis (violating baryon number conservation) period ...
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4 votes
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Why is there not enough CP violation to account for baryogenesis in the SM?

One of Sakharov conditions states that both C and CP symmetries must be violated by a theory which includes any baryogenesis mechanism. The Standard Model happens to be such a theory, and happens to ...
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Antimatter/Matter energy release

I am not a physicist, nor do I have a university degree, but I have a question that has been on my mind for some time. If Antimatter and Matter were created equally during the 'Big Bang' would the ...
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1 answer
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Can an anti-hydrogen atom decay into a hydrogen atom?

I was thinking about Baryon asymmetry just to mess around with ideas and thought about this. Could it be that all the anti-matter decayed into matter?
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3 votes
1 answer
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Baryon number violation in the Standard model at the perturbative and non-perturbative level

This is a continuation of my question here. Page 635 of this book by Matthew Schwartz effectively says that the $\partial_\mu J^\mu_B\neq 0$ where $J^\mu_B$ is the baryon current i.e., the baryon ...
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Quantifying the baryon asymmetry requires normalizing the baryon number density w.r.t comoving entropy density or photon density-Why?

This question has been edited a little to clarify the confusion I have. The matter-antimatter asymmetry of the Universe quantified by the baryon asymmetry as $$Y_B=\frac{n_B-n_{\bar{B}}}{s}=\frac{n_B}...
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Could baryon asymmetry be negative?

In the paper http://hamilton.uchicago.edu/~harvey/pdf_files/harvey_turner_1990.pdf, it can be seen from expressions (9a, 9b,9c) that barygon asymmetry is proportional to negative lepton asymmetry. But ...
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Is the gravitational pull of the early ($10^{10}$ more massive) universe still observable?

During one of the early epochs of the universe it used to be 10^10 times more massive than it is now, just before the matter / antimatter annihilation. So what cosmic gravity is being asserted on the ...
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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?

According to inflation, all the structure that we see like galaxies, etc. originated from quantum fluctuations which were expanded during inflation. But since quantum fluctuations always create ...
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Why is the quantum number $\frac{1}{3}B-L_\alpha$ said to conserved in the Standard model rather than $B-L$?

In the standard model, the baryon number $B$ and the lepton number$L$ are conserved perturbatively. However, the B+L quantum number is anomalous and is violated via non-perturbative effects while ...
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Number excess of baryons per antibaryon in a comoving volume: Interpreting $Y_{\Delta B}$ in the present epoch

The baryon asymmetry of the Universe is quantified in terms of $$\eta=\frac{n_B-n_{\bar B}}{n_\gamma}|_0= (6.21\pm 0.16)\times 10^{-10}\tag{1}$$ or $$Y_{\Delta B}=\frac{n_B-n_{\bar B}}{s}|_0=(8.75\pm ...
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Why does matter-antimatter asymmetry only refer to baryon asymmetry?

Why is the matter-antimatter asymmetry of the Universe quantified by the baryon asymmetry, $$Y_B=\frac{n_B-n_{\bar{B}}}{s}$$ i.e., the difference in the number densities of baryons $n_B$ and ...
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How can we assert $\mathrm{ matter } / \mathrm{ antimatter } \gg 1$ further than $locally$? [duplicate]

I read many hypothesis to explain the asymmetry between the quantity of matter and antimatter in the universe, most notably through an asymmetry in initial baryogenesis. This assymetry would explain ...
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How does inflation get rid of initial Baryon asymmetry (if any)?

Why is it said that even if the baryon asymmetry existed as an initial condition, the asymmetry would have been destroyed by inflation. How does inflation get rid of initial Baryon asymmetry (if any)? ...
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Consequence of C and CP-violation: What does it ensure and what it does not?

This question is a continuation of one of my earlier posts here and the accepted answer. Consider a two-body hypothetical decay $p^+\to e^+\gamma$ in a quantum field theory (say, a GUT). If the ...
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6 votes
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Difference between "C-violation without CP-violation" and "C-violation with CP -violation"

Consider two possible decay channels of a massive particle as $X\to A+B$ and $X\to C+D$ with decay rates $r$ and $1-r$ respectively. Let the decay rates of its antiparticle into channels $\bar X\to \...
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Is proton decay considered in neutron star models (and LHC)?

Although it is definitely not simple, there are many reasons to consider that baryon number can be violated, for example: during baryogenesis (just after Big Bang) there was created more matter than ...
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5 votes
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Why are both C and CP violation necessary for baryogenesis?

Sakharov condition states both C and CP violation is necessary for baryogenesis. Now consider, for example, a theory with B-number violating interaction and C-violation. Therefore, if $p\to e^+\gamma$ ...
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Understanding the fine-tuning problem related to baryon asymmetry as an initial condition

The reason for not assuming the Baryon asymmetry of the universe as an initial condition is often attributed to the following fine-tuning problem: If the baryon asymmetry had been an initial condition,...
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