Leptons are elementary fermions that do not experience the strong interaction: electrons, muons, tauons, and neutrinos.
Questions tagged [leptons]
195 questions
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Why was the first discovered neutrino an anti-neutrino?
In the search for neutrinos, Cowan and Reines discovered the electron anti-neutrino and named it as such. Why is the particle they discovered the anti-variety?
The reason we call electrons 'electrons' and not 'anti-electrons' is because the…
Joshua
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Mixing of quarks, neutrinos... and leptons?
This is a quite simple question: quarks do mix (through the CKM matrix), neutrinos do mix (through the PMNS matrix).
Then why do charged leptons not mix?
riemannium
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Is there a reason, other than mass hierarchy, that we associate each quark generation with a particular lepton generation?
The Standard Model contains three generations of quarks, and three generations of leptons. We generally pair off these generations into the "light" generation ($e, \nu_e, u, d$), the "medium" generation ($\mu, \nu_\mu, c, s$), and the "heavy"…
Michael Seifert
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Could you use Muons as electricity (or rather mutricity)?
Muons and electrons are both leptons that carry charge, so could you build a circuit that uses muons instead of electrons? Do substances like copper that conduct electrons also conduct muons?
qazwsx
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Does substituting electrons with muons change the atomic shell configuration?
Suppose we take an example of $\text{Be}^{2+}$ and we add two muons to it. Will they go into L shell or there will be two K shells - one each for muons and electrons?
If so, the system should have double noble gas ($\text{He}$) configuration?
16
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Why are all quarks and leptons of this universe the same?
We know the composition of stars by spectroscopic analysis. The EM waves generated by them are blue- or redshifted. We could have said, "Look, the wavelength is slightly different so it may be constituted of quarks and leptons which are slightly…
Shubham Kumar
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To what extent are lepton and quark generations tied in the Standard Model?
The Standard Model of particle physics splits both the leptons and the quarks into three generations, with mass and instability going up from the first to the third generation. These are normally displayed together, on the same rows or columns of…
Emilio Pisanty
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Are there any experimental bounds on the ratio of neutrinos to antineutrinos in the universe?
In the Standard Model, both baryon number and lepton number are conserved quantities (excluding the theoretical possibility of sphaleron processes which are exceeding rare, at least at non-"near in time to the Big Bang" energies of circa 10 TeV or…
ohwilleke
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What is the difference between an Electron, a Tau, and a Muon?
What are the basic differences between a Tau, Muon, and Electron? I can read the wikipedia article, but was wondering what specifically distinguished the three leptons and in what experimental contexts they show up.
sakurashinken
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Is It necessary, in the standard model, that the number of quark generations equals the number of lepton generations, i.e. 3?
This question showed up in my particle physics exam and I'm not sure of the answer. I said no, since I can't see any reason why they must be equal.
But I my answer is right, I find it odd that it's just a coincidence that they're both 3.
QuantumDoge
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How do electrons get a charge?
Electrons belong to a group of elementary particles called leptons. There are charged and neutral leptons. And electron is the charged one. But how come it got charged?
The negative or positive charges were assigned by convention. But it is a fact…
Preeti
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Why might $B$ meson decays violate lepton universality?
Scientists from various institutions have recently discovered that there might be a break in the application of the Standard Model, particularly with a fundamental principle called the lepton universality (lepton universality asserts that the…
user159858
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Help me understand Lepton universality
I understand that we have three pairs of Leptons (generations).
$(\nu_e , e^-), (\nu_{\mu}, \mu), (\nu_{\tau}, \tau^-)$
But what is this principle of Lepton universality?
I have obviously tried googling it before asking in here, but all of the sites…
Nillo
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Fundamental reason for the color and flavor group to be the same?
The answer to this question might just be a straight-up "no, it's just a coincidence", but since coincidences are rarely a thing in physics, I thought I'd ask.
Is there a fundamental reason why (take QCD, for example) the gauge (color) group…
Mauro Giliberti
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Why is the conservation of lepton number a thing?
Since there is no way to tell neutrinos and antineutrinos apart, does conservation of lepton number make any sense?
As far as we can tell, the neutrinos and antineutrinos are indistinguishable so from the empirical point of view lepton number is not…
Some Student
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