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Homework Help: Confusing question

  1. Feb 5, 2007 #1
    I will put the question in exact wording that the prof gave us:

    1. The problem statement, all variables and given/known data
    A B+ - B- pair is produced in the decay of at Z0. The B then decays to D + X, where X represents some other particles, with a lifetime of 1.638 x 10^12 s. On average how far will the B0 travel before decaying? This is how the lifetime of the B was measured, by measuring the distance from the production vertex to a secondary vertex where it decayed. (M_B0 = 5.279Gev, M_Z0 = 91.188Gev).

    2. Relevant equations
    All I can think of that may help me (beside a clearer wording of the question) would be:

    [tex] \tau = \frac{1}{\Gamma_{t}} [/tex]
    where $\tau$ is the lifetime of the particle and $\Gamma_{t}$ is the decay width.

    3. The attempt at a solution
    I just don't understand where the B0 comes from in this context? It just appears in the question. Is B0 a combination of B- and B+? How would the hint (at the end of the question, the masses of the particles) be any use if I use the formula in the 2nd part?

    Any thoughts?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 6, 2007 #2

    Meir Achuz

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    Science Advisor
    Homework Helper
    Gold Member

    The B0 in the question must be a misprint. The PDG gives 1.53 as the B0 lifetime, not 1.638, so I don't think the B0 ever enters the problem.
  4. Feb 8, 2007 #3
    Yeah, I asked the prof, and it is a typo... I really dont like it when there is a typo in an assignment.

    It was supposed to be [itex]B^{0}[/itex] and [itex]\bar{B^{0}}[/itex] as a decay process of [itex]Z^{0}[/itex].

    Thanks for the help anyway!
    Last edited: Feb 8, 2007
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