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11.2 Particle Conservation Laws

Baryon number, lepton number, and strangeness assigned to each particle, then totalled before and after to decide whether a reaction or decay can happen.

University Physics Volume 3, 11.2 Particle Conservation Laws

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7 exercises

11.2 Exercise 1

What is the baryon number of a hydrogen nucleus?

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11.2 Exercise 2

What is the lepton number of an electron-positron pair?

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11.2 Exercise 3

What is the strangeness number of a muon?

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11.2 Exercise 4

What are six particle conservation laws? Briefly describe them.

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11.2 Exercise 6

Why might the detection of particle interaction that violates an established particle conservation law be considered a good thing for a scientist?

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11.2 Exercise 7

Which of the following decays cannot occur because the law of conservation of lepton number is violated?

(a)n→p+e−(e)π−→e−+υ−e(b)μ+→e++υe(f)μ−→e−+υ−e+υμ(c)π+→e++υe+υ−μ(g)Λ0→π−+p(d)p→n+e++υe(h)K+→μ++υμ\begin{matrix}\left(\text{a}\right) \text{n} \rightarrow \text{p} + \text{e}^{−} & & & \left(\text{e}\right) \pi^{−} \rightarrow \text{e}^{−} + \left(\overset{−}{\upsilon}\right)_{\text{e}} \\ \left(\text{b}\right) \mu^{+} \rightarrow \text{e}^{+} + \upsilon_{\text{e}} & & & \left(\text{f}\right) \mu^{−} \rightarrow \text{e}^{−} + \left(\overset{−}{\upsilon}\right)_{\text{e}} + \upsilon_{\mu} \\ \left(\text{c}\right) \pi^{+} \rightarrow \text{e}^{+} + \upsilon_{\text{e}} + \overset{−}{\upsilon}_{\mu} & & & \left(\text{g}\right) \Lambda^{0} \rightarrow \pi^{−} + \text{p} \\ \left(\text{d}\right) \text{p} \rightarrow \text{n} + \text{e}^{+} + \upsilon_{\text{e}} & & & \left(\text{h}\right) \text{K}^{+} \rightarrow \mu^{+} + \upsilon_{\mu}\end{matrix}

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11.2 Exercise 9

Identify one possible decay for each of the following antiparticles:

(a) n−\overset{−}{n}, (b) Λ0—\overset{—}{\Lambda^{0}}, (c) Ω+\Omega^{+}, (d) K−\text{K}^{−}, and (e) Σ−\overset{−}{\Sigma}.

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Adapted from University Physics Volume 3 © 2016 Rice University. Licensed under CC BY 4.0. Source: University Physics Volume 3. Imported at revision db44eb9.