Application of Conservation Laws (AQA A Level Physics)

The lambda nought particle Λ⁰ is made up from the quarks uds. Show, in terms of the conservation of charge, strangeness, baryon number and lepton number whether the following interaction is permitted

Answer:

Step 1: Determine conservation of charge

0 = –1 + 1 + 0

            Charge is conserved

Step 2: Determine conservation of strangeness

             Λ⁰ has an s quark, so must have a strangeness of –1

–1 = 0 + 0 + 0

             Strangeness is not conserved

Step 3: Determine conservation of baryon number

             Λ⁰ is a baryon since it has 3 quarks, so must have a baryon number of +1

+1 = 0 + 0 + 0

            Baryon number is not conserved

Step 4: Determine conservation of lepton number

             Λ⁰ is a baryon, so must have a lepton number of 0

0 = 0 + (–1) + 1

            Lepton number is conserved

Step 5: Conclusion

            Since the baryon number is not conserved, this interaction is not permitted

The equation for β^– decay is

Using the quark model of beta decay, prove that the charge is conserved in this equation.

Answer:

Note:

• Quantum numbers for any exotic particles will be given in the question

• All the rest can be found on the datasheet or can be deduced using the information provided