Key Equations
Quarks, Leptons & Conservation Laws — AQA A-Level Physics
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Charge of a quark combination
$$Q_{\text{total}} = \sum Q_{\text{quarks}}$$
- Where:
- $Q_total$ = total charge of the hadron
- $Q_quarks$ = charge of each constituent quark
Up = +2/3, Down = −1/3, Strange = −1/3. Antiquarks have opposite charges.
Baryon number of a quark combination
$$B_{\text{total}} = \sum B_{\text{quarks}}$$
- Where:
- $B_total$ = total baryon number
- $B_quarks$ = baryon number of each quark (+1/3) or antiquark (−1/3)
Baryons (3 quarks): B = 3 × (+1/3) = +1. Mesons (quark + antiquark): B = +1/3 + (−1/3) = 0.