Karteikarten
Ohne Titel
Karten in diesem Stapel (10)
- 1Name three quantities that are conserved in all particle reactions.Quantities that are always conserved in particle reactions are charge, baryon number and lepton number.
- 2What is the baryon number of an electron? Explain your answer.Zero
Why? For baryons, B = +1. For antibaryons B = -1. For all other particles (including electrons), B = 0 - 3Can this reaction take place? Explain your answerNo, the reaction cannot occur because charge is not conserved.
LHS: Q = +1 + (-1) = 0
RHS: Q = +1 + (+1) = +2
- 4Can this reaction take place? Explain your answerYes, the reaction can occur because charge, baryon number and lepton number are all conserved.
- 5Is baryon number conserved in this proposed particle reaction?Yes, baryon number is conserved.
LHS: B = +1 + 0 = +1
RHS: B = 0 + (+1) = +1
- 6Name these particles, and give their charges and baryon numbers.The first particle is a neutral K meson ('kaon').
The second particle is a positive pi meson ('pion').
Both particles are mesons and, therefore, have baryon numbers of zero (because they are not baryons).
- 7Name these particles, and give their charges, baryon numbers, and lepton numbersThe particles are (from the left), a neutron, proton, and an antineutron.
Charges are 0, +1 and 0.
The proton and neutron are both baryons and have baryon numbers (B) of +1. The antineutron is an antibaryon and has B = -1.
All three particles have a lepton number of zero (because they are not leptons).
- 8Is lepton number conserved in this proposed reaction?Yes, lepton number is conserved.
LHS: L = -1 + 0 = -1
RHS: L = -1 + 0 = -1
(The antineutrino and positron are both antileptons)
- 9Is lepton number conserved in this proposed reaction?No, lepton number is not conserved in either the electron or muon family.
Electron family:
LHS: L = 0 + 0 = 0
RHS: L = 0 + (-1) = (-1)
Muon family:
LHS: L = -1 + 0 = -1
RHS: L = 0 + 0 = 0
- 10What is the lepton number of a positron? Explain your answer.L = -1
Why?
For leptons, L = +1.
For antileptons (e.g. the positron) L = -1.
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- Karteikarten am Ohne Titel, erstellt von lthistlewood2013 am 01/09/2014.
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- lthistlewood2013
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