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Conservation laws in particles
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Charge, baryon number and lepton number are conserved.
Charge, energy, momentum, baryon number, lepton number are always conserved; strangeness and parity are conserved in the strong but not the weak interaction.
n → p + e⁻ + ν̄: lepton number 0 = 1 − 1.
Conservation laws guide allowed reactions.
In more detail
Particle physics conserves energy, momentum, charge, lepton number and baryon number. Some conservation laws are broken only by the weak interaction.
Real-world uses
- Conservation laws allow physicists to predict which decays are allowed.
- They help identify new particles in experiments.
- Physicists use conservation laws to decide whether a particle reaction is allowed or forbidden.
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Frequently asked questions
Is strangeness conserved?
It is conserved by the strong and electromagnetic interactions, but not always by the weak interaction.
Can baryon number change?
It is conserved in the Standard Model, though some theories predict proton decay.
Which quantities are always conserved?
Electric charge, energy, momentum, and angular momentum are always conserved, along with baryon and lepton numbers in most reactions.
Related topics in Particle Physics & Cosmology
Confinement · Weak interaction · Electroweak unification · Feynman diagrams · Particle accelerators · Large Hadron Collider