91Ó°ÊÓ

The mean life of the \(\Sigma^{0}\) particle is \(7 \times 10^{-20} \mathrm{~s}\). What is the uncertainty in its rest energy? Express your answer in MeV.

The measured width of the \(\psi(3686)\) meson is about \(300 \mathrm{keV}\). Estimate its mean life.

(1) The measured width of the \(\psi(3686)\) meson is about 300 \(\mathrm{keV}\) . Estimate its mean life.

(I) The B \(^{-}\) meson is a b\overline{u} \text { quark combination. } ( a ) \text { Show that } this is consistent for all quantum numbers. (b) What are the quark combinations for \(\mathrm{B}^{+}, \mathrm{B}^{0}, \mathrm{B}^{0} ?\)

(II) Which of the following decays are possible? For those that are forbidden, explain which laws are violated. (a) \(\Xi^{0} \rightarrow \Sigma^{+}+\pi^{-}\) \((b) \Omega^{-} \rightarrow \Sigma^{0}+\pi^{-}+\nu\) \((c) \Sigma^{0} \rightarrow \Lambda^{0}+\gamma+\gamma\)

What quark combinations produce \((a)\) a \(\Xi^{0}\) baryon and (b) a \(\Xi^{-}\) baryon?

What are the quark combinations that can form \((a)\) a neutron, \((b)\) an antineutron, (c) a \(\Lambda^{0},(d)\) a \(\bar{\Sigma}^{0} ?\)

(II) What particles do the following quark combinations produce: \((a)\) uud, \((b) \overline{\mathrm{u}} \overline{\mathrm{u}} \overline{\mathrm{s}},(c) \overline{\mathrm{u}} \mathrm{s},(d) \mathrm{d} \overline{\mathrm{u}},(e) \overline{\mathrm{c}} \mathrm{s} ?\)

What is the quark combination needed to produce a \(\mathrm{D}^{0}\) meson \((Q=B=S=0, c=+1) ?\)

(II) What is the quark combination needed to produce a D' meson \((Q=B=S=0, c=+1) ?\)