Questions tagged [leptons]

Leptons are elementary fermions that do not experience the strong interaction: electrons, muons, tauons, and neutrinos.

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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?
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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'...
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The physical meaning of electromagnetic waves

What, fundamentally, is an electromagnetic wave? As far as I know, all wave phenomena are derivations of an oscillating processes, e.g. particles vibrating in a medium. I can't imagine a wave process ...
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About the reason why the change of a muon into an electron plus a photon is not seen

Let me state first that I don't think this is a duplicate of the mentioned question, though the basic thought is the same. Nevertheless, I come up with the prequark rishon theory of Harari, which ...
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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 ...
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Does string theory explain the existence of 3 generations of quarks/leptons?

I am wondering whether string theory explains the existence of 3 families of quarks/leptons or not. I have a very limited understanding of string theory, as of now, and I have a mathematical ...
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2answers
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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 ...
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1answer
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Representation in $SU(2)_{L}\times U(1)_{Y}$

I'm reading the book "Massive neutrinos in physics and astrophysics" by R. N. Mohapatra and P. B. Pal, and have a question about its notation. The Equation 2.10, it says: $$ q_{L}=\binom{u_{L}}{d_{L}}...
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1answer
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Would it be consistent with QED to have leptons of different charges?

A recent question, Equality of electric charges of all leptons, made me wonder about a specific aspect of why exactly the charges of the different (free) fundamental particles are all the same. ...
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1answer
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Ratio of electrons and protons in Universe

What is the relation between amount of electrons and protons in Universe? I expect that the Universe should not be charged, so the estimation is 1:1. But then, why there should be the same amount of ...
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1answer
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Is it at least theoretically possible for an electron and an antimuon or antitauon to annihilate?

In other words, can mismatched particles and antiparticles react with each other? What about an up quark and anti-down quark?
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1answer
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How does Bhabha scattering imply the existence of quark/lepton substructure?

In the 1983 journal article New Tests for Quark and Lepton Substructure which covers some science and mathematics behind quark and lepton composition (theoretical). It says: Bhabha-scattering ...
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The stunning footage of neutral currents, first observation of a neutrino: Knowledge needed

First of all, this question is purely motivated by curiosity. I call upon the community's knowledge on the matter. Following the link below, you can see the image of "A lepton event - a neutrino ...