Key Stage 5
Meaning
Quarks (q) are a type of fermion and are the constituent parts of hadrons.
About Quarks
- 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:
- Up-quark - With a charge of \(+\frac{2}{3}\)e, two of which are found in proton and one of which is found in a neutron.
- Down-quark - With a charge of \(-\frac{1}{3}\)e, two of which are found in a neutron and one of which is found in a proton.
- Strange-quark - With a charge of \(-\frac{1}{3}\)e which decays quickly via the weak interaction into a down-quark.
- Top-quark - With a charge of \(+\frac{2}{3}\)e which decays quickly via the weak interaction.
- Bottom-quark - With a charge of \(-\frac{1}{3}\)e which decays quickly via the weak interaction.
- Charm-quark - With a charge of \(+\frac{2}{3}\)e which decays quickly via the weak interaction.
Conserved Quantities
| Quark | Charge/e | Strangeness | Baryon Number | Lepton Number |
| \(q=+\frac{2}{3}\) | \(S=0\) | \(b=+\frac{1}{3}\) | \(l=0\) | |
| \(q=-\frac{1}{3}\) | \(S=0\) | \(b=+\frac{1}{3}\) | \(l=0\) | |
| \(q=-\frac{1}{3}\) | \(S=-1\) | \(b=+\frac{1}{3}\) | \(l=0\) | |
| \(q=+\frac{2}{3}\) | \(S=0\) | \(b=+\frac{1}{3}\) | \(l=0\) | |
| \(q=-\frac{1}{3}\) | \(S=0\) | \(b=+\frac{1}{3}\) | \(l=0\) | |
| \(q=+\frac{2}{3}\) | \(S=0\) | \(b=+\frac{1}{3}\) | \(l=0\) |
| Antiquark | Charge/e | Strangeness | Baryon Number | Lepton Number |
| \(q=-\frac{2}{3}\) | \(S=0\) | \(b=-\frac{1}{3}\) | \(l=0\) | |
| \(q=+\frac{1}{3}\) | \(S=0\) | \(b=-\frac{1}{3}\) | \(l=0\) | |
| \(q=+\frac{1}{3}\) | \(S=+1\) | \(b=-\frac{1}{3}\) | \(l=0\) | |
| \(q=-\frac{2}{3}\) | \(S=0\) | \(b=-\frac{1}{3}\) | \(l=0\) | |
| \(q=+\frac{1}{3}\) | \(S=0\) | \(b=-\frac{1}{3}\) | \(l=0\) | |
| \(q=-\frac{2}{3}\) | \(S=0\) | \(b=-\frac{1}{3}\) | \(l=0\) |