4.5.123 - Charge, baryon and lepton number conservation

Understand how to use laws of conservation of charge, baryon number and lepton number to determine whether a particle interaction is possible.

Use - charge, baryon and lepton number conservation to connect the rule to the data and decision in the question.

This matters because - charge, baryon and lepton number conservation determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - charge, baryon and lepton number conservation to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Charge, baryon and lepton number conservation is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.