Questions tagged [baryogenesis]

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6
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0answers
31 views

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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1answer
65 views

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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37 views

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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2answers
69 views

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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1answer
33 views

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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1answer
111 views

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 ...
2
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3answers
82 views

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 ...
3
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3answers
69 views

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 ...
0
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1answer
60 views

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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0answers
34 views

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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4answers
8k views

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
130 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
330 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 ...
3
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1answer
93 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 ...
5
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1answer
222 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 ...
0
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1answer
111 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 ...
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3answers
94 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
77 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
126 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
115 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
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2answers
162 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
207 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
160 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
50 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
177 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
135 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
46 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
65 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 ...
14
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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
149 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 ...
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3answers
169 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
236 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
108 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
310 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
144 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
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1answer
278 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 \...
5
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2answers
370 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 ...
5
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1answer
561 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
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2answers
202 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
385 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
165 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
899 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
45 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
392 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
212 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
427 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 ...
2
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0answers
62 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
137 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
97 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
76 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 ...