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Quark

Key Stage 5

Meaning

Quarks (q) are a type of fermion and are the constituent parts of hadrons.

About Quarks

The quark is denoted with a lower case q.
Quarks are believed to be fundamental particles but they have never been observed on their own.
Quarks always exist as part of hadron including a baryon, which is a triplet of quarks or a meson which is a quark-antiquark pair.
There are 6 types of quark including:

(The following are not on all A-level syllabi)

Conserved Quantities

Properties of the quarks.
Quark Charge/e Strangeness Baryon Number Lepton Number

Up-quark

\(Q=+\frac{2}{3}\) \(S=0\) \(B=+\frac{1}{3}\) \(L=0\)

Down-quark

\(Q=-\frac{1}{3}\) \(S=0\) \(B=+\frac{1}{3}\) \(L=0\)

Strange-quark

\(Q=-\frac{1}{3}\) \(S=-1\) \(B=+\frac{1}{3}\) \(L=0\)

Top-quark

\(Q=+\frac{2}{3}\) \(S=0\) \(B=+\frac{1}{3}\) \(L=0\)

Bottom-quark

\(Q=-\frac{1}{3}\) \(S=0\) \(B=+\frac{1}{3}\) \(L=0\)

Charm-quark

\(Q=+\frac{2}{3}\) \(S=0\) \(B=+\frac{1}{3}\) \(L=0\)
Properties of the antiquarks
Antiquark Charge/e Strangeness Baryon Number Lepton Number

Antiup-quark

\(Q=-\frac{2}{3}\) \(S=0\) \(B=-\frac{1}{3}\) \(L=0\)

Antidown-quark

\(Q=+\frac{1}{3}\) \(S=0\) \(B=-\frac{1}{3}\) \(L=0\)

Antistrange-quark

\(Q=+\frac{1}{3}\) \(S=+1\) \(B=-\frac{1}{3}\) \(L=0\)

Antitop-quark

\(Q=-\frac{2}{3}\) \(S=0\) \(B=-\frac{1}{3}\) \(L=0\)

Antibottom-quark

\(Q=+\frac{1}{3}\) \(S=0\) \(B=-\frac{1}{3}\) \(L=0\)

Anticharm-quark

\(Q=-\frac{2}{3}\) \(S=0\) \(B=-\frac{1}{3}\) \(L=0\)