Subatomic Physics

496 Quark Models of Mesons and Baryons
The discovery of the top quark and the top quark are discussed by P.L. Tipton,
Sci. Amer. 277, 54 (Sept. 1997); S. Willenbrock, Rev. Mod. Phys.72, 1141 (2000);
K. Tollefson and E.W. Varnes, Annu. Rev. Nucl. Part. Sci. 49, 435 (1999).
Toponium is discussed by J. H. Kuhn and P. M. Zerwas, Phys. Rep. 167, 321
(1988); C. Quigg Phys.Today 50, 19 (May 1997).
Asymptotic freedom and the confinement of quarks is described by F. Wilczek,
Rev. Mod. Phys. 77, 857 (2005), and C. Rebbi, Sci. Amer. 248, 54 (February
1983). Lattice work on this aspect of QCD is reviewed in a recent very readable
articlebyS.R.SharpeinGlueballs, Hybrids, and Exotic Hadrons, (S-W. Chung,
ed.) Amer. Inst. Phys. Confer. Proc. 185, AIP, New York, 55 (1989).
Regge phenomenology is reviewed by A. C. Irving and R. P. Worden, Phys. Rep.
34, 144 (1977); L. Caneshi, ed., Regge Theory and Low pT Hadronic Interactions,
North Holland, Amesterdam, 1989. Descriptions can also be found in the texts
listed at the beginning of this Section.
Problems
15.1. Assume that the nonstrange quarks u and d are stable as free particles. Describe
their fate upon entering a solid. What will the ultimate fate of either
one be, and where do you expect them to come to rest?
15.2. Describe possible ways to search for quarks at accelerators. How are quarks
distinguished from other particles? What limits the mass of the quark that
can be found?
15.3. Could quarks be seen in a Millikan-type (oil drop) experiment? Estimate the
lower limit of the concentration that can be observed in an ordinary oil droplet
experiment. How can the approach be improved?
15.4. Use the quark model to compute the ratio of the magnetic moment of the
proton to that of the neutron.
15.5. Use a simple potential well with range given by the proton radius to discuss
the validity of the nonrelativistic treatment of the constituent quarks in the
simple quark model.
15.6. Justify that only one baryon state can be formed from three identical quarks
with L = 0; verify that this state corresponds to a particle with spin 3/2.
15.7. (a) Prove that the square of the sum of two angular momentum operators,
J and J ′ , can be written as
(J + J ′ ) 2 = J 2 + J ′2 +2J · J ′
= J 2 + J ′2 +2JzJ ′ z + J+J ′ − + J−J ′ +,