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Established physics · Lesson 20 of 34

The first family, field by field

Up, down, electron, and electron-neutrino labels have distinct charges and interaction rules.

Free science education from TRQC™ · Timeline-Relative Quantum Collapse™, for academic study.

401 · ordinary matter at the source

Up quark

The up field has spin 1/2, charge +2/3, and color. Its excitations take part in strong, electromagnetic, and weak interactions. A commonly quoted up-quark mass is roughly 2 MeV, with scheme and scale understood; it is not a free isolated quark you can place on a balance.

Down quark

The down field also carries color and spin 1/2, but charge −1/3 and a mass roughly 5 MeV in a common convention. A charged weak process can connect up-type and down-type quark states. The proton mass is not the sum of two up masses and one down mass: QCD binding dynamics contribute most of it.

Electron

The electron has spin 1/2, electric charge −1, no color, and mass 0.511 MeV. It couples to the photon and weak bosons; its Higgs Yukawa coupling is related to its mass. Left and right chiral parts have different weak quantum numbers, while both take part in electromagnetism.

Electron neutrino

The electron-neutrino label identifies the weak flavor produced alongside an electron in suitable processes. Its charge is 0 and it has no color; it interacts weakly. It is not a fixed-mass particle species: a flavor state is a mixture of light neutrino mass states, and the mechanism of neutrino mass is beyond the minimal massless-neutrino model.

A vertex check

In beta decay, a down-type quark can change to an up-type quark through a W-mediated weak process, ultimately producing an electron and electron antineutrino. The sum of charges balances. The quarks remain confined within hadrons; the diagram is a calculation of allowed field connections, not a photograph.

Compare, do not merge

All four are fermionic labels, but up and down have color, electron carries only electric and electroweak charges, and neutrino is electrically neutral. Shared spin does not make them excitations of one undifferentiated matter field.

Same family, different charges
Up+2/3 · colorstrong + EM + weak
Down−1/3 · colorstrong + EM + weak
Electron−1 · no colorEM + weak
νe flavor0 · no colorweak

Yukawa/Higgs couplings of massive charged fermions are discussed in the atlas; neutrino masses need an extension.

Takeaway: The first family is one generation, not one field.

Check your understanding

Which first-family labels carry color?

  1. Up and down quarks
  2. Electron and neutrino
  3. All four
Answer and explanation

Up and down quarks

Quarks are color triplets; leptons are color singlets.

Why does an electron couple directly to a photon?

  1. It has electric charge −1
  2. It has color
  3. It is the lightest fermion
Answer and explanation

It has electric charge −1

Photon coupling follows electric charge.

Which first-family field has electric charge +2/3?

  1. Up quark
  2. Down quark
  3. Electron neutrino
Answer and explanation

Up quark

The up quark has charge +2/3.

Can one assign a single measured mass to an electron-neutrino flavor?

  1. No; flavor mixes neutrino mass states
  2. Yes, exactly 0.511 MeV
  3. Yes, exactly the W mass
Answer and explanation

No; flavor mixes neutrino mass states

A flavor state is a superposition of mass eigenstates.

What dominates a proton’s mass?

  1. QCD dynamics and energy
  2. Simply adding three light quark mass parameters
  3. Three electron masses
Answer and explanation

QCD dynamics and energy

The dynamics of confined quarks and gluons dominate.

In a weak down-to-up transition, what must still balance?

  1. Electric charge
  2. The individual quark flavor label
  3. The number of gluon diagrams
Answer and explanation

Electric charge

Charge conservation applies at each allowed vertex.

Use the interactive trainer for demonstrations, the field explorer, and saved checkpoint progress.