🔋college physics i – introduction review

Baryon number

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Baryon number is a quantum number representing the difference between the number of baryons and antibaryons in a system. It is conserved in most particle interactions, meaning the total baryon number remains constant.

5 Must Know Facts For Your Next Test

  1. Baryon number is defined as $B = \frac{1}{3}(n_q - n_{\bar{q}})$, where $n_q$ is the number of quarks and $n_{\bar{q}}$ is the number of antiquarks.
  2. Protons and neutrons each have a baryon number of +1.
  3. Antiprotons and antineutrons each have a baryon number of -1.
  4. In any nuclear reaction or particle decay, the total baryon number before and after the process must be equal.
  5. Leptons have a baryon number of 0.

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