78 votes

Why are all quarks and leptons of this universe the same?

Fairy Physics It is entirely possible to construct a theory of the universe which states: "All effects are caused by fairies. Each effect has its own fairy, and every fairy is unique. When two ...
Lawnmower Man's user avatar
41 votes
Accepted

Why was the first discovered neutrino an anti-neutrino?

To maintain lepton number as a conserved quantity. Consider, in detail, what's going on in a beta decay (well, I'm going to ignore the nuclear context). The reaction is then $$ n \longrightarrow p^+ + ...
dmckee --- ex-moderator kitten's user avatar
27 votes

Could you use Muons as electricity (or rather mutricity)?

You can use any charged particle to carry an electric current. We like to say that current is carried by electrons because, in metallic conductors, there is a gas of conduction electrons who are much ...
rob's user avatar
  • 89.9k
22 votes

Why are all quarks and leptons of this universe the same?

We know that the spectral lines in the spectrum of a binary star shift one way and then the other and this is correlated with its position in its orbit around its companion. Clearly, the constituents ...
gandalf61's user avatar
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22 votes
Accepted

Could you use Muons as electricity (or rather mutricity)?

For the purposes of this answer, I'll be ignoring the fact that muons have a very short lifetime, and instead talking about how a fantasy version of a muon, one that is identical in every way to real-...
Hearth's user avatar
  • 389
19 votes
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What is the difference between an Electron, a Tau, and a Muon?

They only differ in their masses. How they interact with other particles, their charge, their lepton number, everything else is the same. In fact they appear in the SM lagrangian just as three ...
Davide Morgante's user avatar
18 votes
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Can muons decay into quarks?

No, muons can't decay into quarks because quarks are confined; the final product cannot be quarks, but rather composite particles made of quarks, such as mesons and baryons. The lightest mesons are ...
knzhou's user avatar
  • 102k
18 votes

Does substituting electrons with muons change the atomic shell configuration?

Muons, due to their higher mass, have a much smaller Bohr radius in an atom than electrons do. Muons have two spin states, just like electrons, so two muons can occupy the same orbital. A Be muonic ...
John Doty's user avatar
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17 votes

What is the difference between an Electron, a Tau, and a Muon?

Davide gives the theoretical side. Experimentally, in detecting them, there is a large difference. Electrons have been detected long ago: cathode ray tubes and then the Millikan oil drop experiment ...
anna v's user avatar
  • 234k
17 votes
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Does substituting electrons with muons change the atomic shell configuration?

A nucleus with both bound muons and bound electrons will have separate shell structures for the distinguishable leptons. A useful comparison is the nuclear shell model, in which nucleons are arranged ...
rob's user avatar
  • 89.9k
13 votes
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Why is the conservation of lepton number a thing?

Neutrinos and antineutrinos are indistinguishable by most of their qualities, butt not all. One of the quantities that distinguish them is exactly the lepton number, which make them interact with ...
Adam Latosiński's user avatar
11 votes
Accepted

Fundamental reason for the color and flavor group to be the same?

It's just a coincidence. Note that the original flavour $SU(3)$ permuting up, down and strange is broken by the differing masses, and the less badly broken $SU(2)$ is the isospin group. Both are thus ...
Toffomat's user avatar
  • 4,148
11 votes

What happens when an anti-electron collides with a neutrino?

The only way the anti-electron $e^+$ and a neutrino $\nu$ can interact is by the weak interaction, i.e. mediated by a $W$ or $Z$ boson. There are several reactions possible, here shown as Feynman ...
Thomas Fritsch's user avatar
10 votes
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Can muonic atoms exist?

Absolutely they can exist. In fact, physicists often creat muonic hydrogen to study things like the structure/size of the proton with more accuracy. The reason we don't see muonic/tauonic atoms in ...
Bob Knighton's user avatar
  • 8,460
10 votes

Why are all quarks and leptons of this universe the same?

Other answers have correctly given some of the reasons. I am merely going to add that ultimately this is a question that bears on a very large number of different observations, on the concept of ...
Andrew Steane's user avatar
9 votes

Mixing of quarks, neutrinos... and leptons?

Somewhat reluctantly, I decided to add to the otherwise excellent technical answers above, since none confronted the fundamental false premise of your question, "why do charged leptons not mix?&...
Cosmas Zachos's user avatar
9 votes
Accepted

Can protons and neutrons be completely converted into Leptons?

Protons and neutrons are members of a class of particles called baryons; and according to the Standard Model of particle physics, baryon number is conserved. Protons and neutrons both have baryon ...
Michael Seifert's user avatar
8 votes

What are the advantages of an electron-electron collider vs. An elec./positron one? Has one ever been built?

There was VEP-1 electron-electron collider in 1960s, see arXiv:1307.3116. The advantage of electron-electron colliders is that one only needs to deal with electrons, which is easier than dealing with ...
akhmeteli's user avatar
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7 votes
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Which came first: leptons or baryons?

There exists a standard model of cosmology, i.e. accepted as the current status of research, called the Big Bang. This makes extensive use of the known interactions of particle physics encapsulated ...
anna v's user avatar
  • 234k
7 votes
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What are the advantages of an electron-electron collider vs. An elec./positron one? Has one ever been built?

As akhmeteli says, there have been electron electron colliders. Note the date (1968) and the reason for making the collider: The overall goal of the project was to check the limits of applicability ...
anna v's user avatar
  • 234k
7 votes

Why are all quarks and leptons of this universe the same?

Actually 2 questions: The title: why are leptons and quarks all the same? We don't know, but we have a good model for them and it works pretty well. In this model, particles emerge as a solutions to ...
fraxinus's user avatar
  • 7,906
7 votes

What is $a_\mu$ in particle physics? In terms of a muon; and its magnetic moment? What is, '$a_\mu$ × $10^9$ - 1165900 '?

The spin magnetic moment of a fundamental particle with mass $m$, charge $q$, and spin 1/2 is $$\vec\mu=g\frac{q}{2m}\vec S$$ where $\vec S$ is its spin vector. The "$g$-factor" is a ...
G. Smith's user avatar
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7 votes
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Is the muon superfluous?

In the Standard Model, the mathematical transformation between “matter” and “antimatter” is called $\newcommand\CP{\mathit{CP}}\CP$. To transform matter to antimatter mathematically, you must “...
rob's user avatar
  • 89.9k
7 votes

Does substituting electrons with muons change the atomic shell configuration?

Here is a hand wavy explanation. Electrons are very light. They must be treated quantum mechanically, while the nucleus can be treated classically. The nucleus is treated as a point source of charge ...
mmesser314's user avatar
  • 38.6k
6 votes
Accepted

Lagrangian of Yukawa Interaction and Quark Mixing

In fact, the Yukawa Lagrangian is (more or less) only the term $\mathcal{L}_Y = -g \bar{\psi}\psi \phi$. The (massless) Dirac Lagrangian for fermions and Klein-Gordon Lagrangian (plus potential) for ...
Bosoneando's user avatar
  • 5,644
6 votes
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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?

Honest answer for your question is ''No''! As in the standard model (SM), the number of fermion generations appears as an arbitrary parameter, meaning that a mathematically consistent theory can be ...
Mass's user avatar
  • 2,020
6 votes

Is it at least theoretically possible for an electron and an antimuon or antitauon to annihilate?

A left-handed up quark and a left-handed anti-down quark can annihilate into a W boson because of the nature of the weak interactions. Right-handed quarks do not interact via W boson because W boson ...
Oktay Doğangün's user avatar
6 votes
Accepted

Decay width of the tau lepton

The decay width $\Gamma=K m^5 $is an approximation that holds when all final state particles are much lighter than the decaying particle. For the muon, there is only one decay mode(the muon is not ...
Lunaron 's user avatar
6 votes

Is there a reason, other than mass hierarchy, that we associate each quark generation with a particular lepton generation?

There is NO reason, other than mass hierarchy, that we associate each quark generation with a particular lepton generation. The standard generation assignment $$ (e, \nu_e, u, d)\\ (\mu, \nu_\mu, c, ...
MadMax's user avatar
  • 3,832
6 votes

Why are all quarks and leptons of this universe the same?

I want to expand on the comment I made to gandalf61 's answer. Spectroscopic binary systems are usually detected due to the movement of the emission and absorption lines in the observed spectrum, ...
anna v's user avatar
  • 234k

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