Questions tagged [baryogenesis]
The baryogenesis tag has no usage guidance.
68
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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 ...
2
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1answer
109 views
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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1answer
80 views
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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1answer
45 views
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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0answers
25 views
Why do we have constraints on the baryon asymmetry of the universe and not the lepton asymmetry?
What is it about baryons that means that CMB observations can determine their asymmetry without also including a charged leptonic component?
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0answers
31 views
Why do we assume that there had to be a baryon-antibaryon-symmetry in the first place?
Maybe this is obvious to some, however I have not found a satisfying answer yet.
Detailed answers appreciated!
5
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1answer
197 views
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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1answer
88 views
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 ...
0
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1answer
35 views
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 ...
2
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1answer
76 views
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 ...
0
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1answer
113 views
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 ...
3
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1answer
103 views
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 ...
4
votes
2answers
137 views
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 ...
4
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0answers
158 views
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 ...
2
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1answer
150 views
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 ...
0
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1answer
48 views
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?
3
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1answer
150 views
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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1answer
108 views
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
$$Y_B=\frac{n_B-n_{\bar{B}}}{s}=\frac{n_B}...
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0answers
45 views
Could baryon asymmetry be negative?
In the paper http://hamilton.uchicago.edu/~harvey/pdf_files/harvey_turner_1990.pdf,
it can be seen from expressions (9a, 9b,9c) that barygon asymmetry is proportional to negative lepton asymmetry. But ...
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3answers
61 views
Is the gravitational pull of the early ($10^{10}$ more massive) universe still observable?
During one of the early epochs of the universe it used to be 10^10 times more massive than it is now, just before the matter / antimatter annihilation. So what cosmic gravity is being asserted on the ...
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2answers
1k views
If all the Structure in our visible Universe originated from Quantum Fluctuations, why isn't there as much Anti-Matter as Matter?
According to inflation, all the structure that we see like galaxies, etc. originated from quantum fluctuations which were expanded during inflation. But since quantum fluctuations always create ...
0
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1answer
124 views
Why is the quantum number $\frac{1}{3}B-L_\alpha$ said to conserved in the Standard model rather than $B-L$?
In the standard model, the baryon number $B$ and the lepton number$L$ are conserved perturbatively. However, the B+L quantum number is anomalous and is violated via non-perturbative effects while ...
0
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3answers
151 views
Number excess of baryons per antibaryon in a comoving volume: Interpreting $Y_{\Delta B}$ in the present epoch
The baryon asymmetry of the Universe is quantified in terms of $$\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 ...
3
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2answers
197 views
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 ...
0
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1answer
104 views
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 ...
3
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2answers
243 views
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)?
...
2
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0answers
132 views
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 ...
5
votes
1answer
230 views
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 \...
4
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1answer
260 views
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 ...
3
votes
1answer
380 views
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 $p\to e^+\gamma$ ...
5
votes
2answers
172 views
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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1answer
308 views
Theta Vacuum of Yang-Mills theory and Baryon number violation
Background 1. In classical SU(N) Yang-Mills theories, there are a countably infinite number of homotopically inequivalent gauge field configurations of zero energy labelled by a winding number $n\in \...
4
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1answer
157 views
Is this article about the SMASH hypothesis a fair assessment?
New Scientist is gushing as usual about a new development in physics. This one, called SMASH, looks truly interesting, though.
Apparently it's a small extension to the Standard Model that explains "...
4
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2answers
848 views
How do sufficiently energetic photons form electrons-positron pairs?
If the question seems strange, here's the wikipedia snippet that drives it:
The Big Bang theory is the most widely accepted scientific theory to explain the early stages in the evolution of the ...
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0answers
39 views
Possible intermediate scales of baryogenesis?
The conventional beyond Standard Model explanation of baryogenesis is that, within Grand Unified Theories (GUT), there exist some new heavy scalar bosons of mass $M_{\rm GUT}\sim10^{15}$ GeV, which ...
12
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1answer
326 views
Understanding Sakharov's third condition for baryogenesis (departure from thermal equilibrium)
I'm struggling to understand Sakharov's third condition for baryogenesis, i.e., a departure from thermal equilibrium. I don't understand what thermal equilibrium means in this context or proofs that ...
8
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1answer
192 views
Does Leptogenesis require lepton number violating vertices?
One of the Sakharov condition for Baryogenesis requires Baryon number violating interactions in the theory. However, it is also possible to generate a baryon asymmetry via a lepton asymmetry or ...
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1answer
406 views
Why do we believe baryon asymmetry?
The question is that how can we make sure that our universe is baryon asymmetric? I mean, is it possible that there are antimatter domains beyond some very large scale. Yes, if that kind of domains ...
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0answers
53 views
How many times does baryogenesis happen during the history of the universe?
Does the baryogenesis happen both in GUT epoch and electroweak Epoch during the history of the universe? If yes, are there any differences during this two times?
2
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1answer
119 views
Baryon / lepton number violation equivalence in Sakharov conditions
In the Sakharov conditions for matter-antimatter asymmetry the requirement for the baryon number violation is often interchanged with lepton number violation. In the context of the Sakharov conditions,...
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1answer
93 views
Baryon - Anti Baryon scattering
Is it possible, for a strong interaction of the above described type (baryon - anti baryon), to exist?
$$B + \bar B \to \ldots $$
(Where $B$ is a generic baryon and $\bar B$ the anti-)
Namely like ...
1
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1answer
72 views
How was there an extra particle in the early universe?
According to theories.. In the early universe.. There were particles and anti-particles in equal number.. But there seems to be one extra particle against the number of anti-particles.. As the ...
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1answer
2k views
Does the number density of photons $n_\gamma\approx 10^8 \:\mathrm m^{-3}$ refer to CMB photons only?
When we talk about the present-day number density of photons ($n_\gamma\approx 10^8 \:\mathrm m^{-3}$) in the universe do we mean the number density of CMB photons? I mean there are other sources of ...
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0answers
66 views
Asymmetry vs. Simple Statistics WRT Matter / Antimatter Ratios
I'm not clear on why physicists suspect, and are looking for, an asymmetry in nature that favors matter over antimatter. Here's a simple thought experiment to illustrate my confusion: Assume I have ...
2
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1answer
76 views
C&CP-Symmetry Violation in Baryogenesis
In cosmology, during the big bang; how does C-Symmetry violation allow for a greater number of baryons to be produced than anti-baryons in Baryogenesis, similarly how does CP-Symmetry tie into this?
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1answer
254 views
EW phase transition and baryogenesis
There are three Sakharov conditions of baryogenesis:
CP symmetry violation.
Baryon number conservation violation.
Thermodynamical equilibrium violation.
In SM the first one is satisfied by CKM ...
4
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2answers
142 views
Questions about the strange character of antimatter
Its been a few days and i have just been introduced to the concept of antimatter. Every Speck of matter in the world has its anti form basically that we have antimatter whenever we have matter. But I ...
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0answers
65 views
Few questions about SM baryogenesis
SM provides baryogenesis via leptogenesis due to anomalies and sphaleron processes. I have a few questions on it.
How exactly the anomalies in lepton and baryon currents provide convertation of ...
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1answer
408 views
How exactly sphaleron transitions erase initial baryon asymmetry, if any?
The sphaleron interactions in the Standard Model (SM) is $(B-L)$ conserving and $(B+L)$ violating. Each sphaleron transition causes the change in the baryon number $\Delta B$ and the lepton number $\...
2
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1answer
150 views
Phase transition and effect on leptogenesis
What is the effect on leptogenesis in the standard model if the electroweak phase transition is (i) first order and (ii) second order?
