Questions tagged [leptogenesis]
32 questions
19
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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 photons, for example, stellar or galactic…
SRS
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14
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4 answers
Temperature of electroweak phase transition
How does one estimate the temperature at which electroweak phase transition (EWPT) occurred? Somewhere I have read it is around 100GeV but the reason was not explained.
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12
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Difference between instantons and sphalerons
What is the difference between instantons and sphalerons? If they are different, how do they violate baryon and lepton number in the standard electroweak theory?
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8
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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 Leptogenesis. Therefore, for Baryogenesis through…
SRS
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8
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Why is baryon or lepton violation in standard model is a non-perturbative effect?
The baryon number B or lepton number L violation in the standard model arise from triangle anomaly. Right? Triangle diagrams are perturbative diagrams. Then why the B or L violation in Standard model is said to be a non-perturbative effect? I'm…
SRS
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7
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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 argumentation about this fact. By that, I mean that we know…
thephysics17
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5
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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 $p\to e^+\gamma$ is an allowed B-violating process, C-violation…
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5
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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, then, for every 6,000,000 antiquarks, there…
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5
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Singlet neutrinos decaying to Higgs bosons during leptogenesis
(i) The Lagrangian of electroweak model extended with right-chiral singlet neutrinos $N_{iR}$ contains the Yukawa coupling term+ the bare Majorana mass term $$f_{\alpha i}\overline{l_{L\alpha}}\hat\phi N_{Ri}+M_{ij}\overline{N^c_{iR}}N_{jR}$$ where…
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4
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Is there a lepton anti-lepton asymmetry?
I dont know is this a stupid question or not but I wanted to ask
We all familiar with the fact that there must be some more baryons w.r.t antibaryons. Since we do not observe any anti-baryons we claim that
$$N_B - \overline{N}_B = \eta…
camarman
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4
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2 answers
Why does matter-antimatter asymmetry only refer to baryon asymmetry?
Why is the matter-antimatter asymmetry of the Universe quantified by the baryon asymmetry,
$$Y_B=\frac{n_B-n_{\bar{B}}}{s}$$
i.e., the difference in the number densities of baryons $n_B$ and antibaryons $n_{\bar{B}}$ normalized w.r.t the entropy…
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4
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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)?
EDIT: For reference see the section 1.1 (last…
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3
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2 answers
What order did the particles of nature appear in?
in the epochs of the very early universe, the different forces separated from each other in succession. if this is true then at one point there was an electroweak force. and before that, there was the electronuclear force, and before that all four…
blacktopshaman
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3
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1 answer
Assumptions for Leptogenesis
In a video by Fermilab's YouTube channel "Can leptogenesis explain why there is something instead of nothing?", host Dr. Lincoln states four assumptions for the theory of leptogenesis. One of them is that neutrinos are Majorana particles - that is,…
MathTrain
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3
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3 answers
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 the ways of inferring the amount of baryon…
SRS
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