D mixing is in principle sensitive to supersymmetry.

The idea is that in the Standard Model, D mixing is suppressed by two factors: the first is Cabibbo Suppression, accounting for a suppression by tan^2(theta_c) which is about 0.05. The second is due to the mass of the light quarks that inhabit D mixing box diagrams; while relatively heavy quarks (the charm and the top) populate the K and B mixing box diagrams, providing enhancements, it is light quarks (the down and the strange) that populate the D mixing box, causing suppressions.

Supersymmetry would replace the down and strange quarks in the D mixing amplitudes with heavy squarks, and thus the mass suppression would be lifted. However, a lot of complexity enters, because so many unknowns are present: masses of squarks and gauginos (gluinos, Winos, etc.), sCabibbo matrix elements, as well as parameters that describe odd things like mixing between squarks that are superpartners of the respective left and right-handed quark projections.

One must be satisfied with broad estimates of sensitivity.

One paper with a brief discussion of D mixing and SUSY is here; the key equation is number 8. Another useful reference is here; in this reference, the squarks are assumed to be degenerate in mass, an assumption not made in the first reference.

From an experimentalist's perspective, it is useful to compare the relative sensitivity of K, D and B mixing. There are some simple scaling laws that allow one to compare the change in x=(Delta M)/Gamma that a new amplitude with *flavor-universal* couplings would cause.

The answer is: if x in the neutral kaon system were to change by 1 unit, one would expect x in the D0 system to change by 0.01 units, and x in the B0_d system to change by 0.1 units.

The mixing parameter x is 0.95 for neutral kaons (note, some sources say 0.48, which neglects the fact that the K^0_S lifetime is half the K^0 lifetime), so a sensitivity to x=0.01 in D mixing starts to become comparable to the sensitivity of kaon mixing to new amplitudes. Similarly, x is 0.7 for the B^0_d system, so a sensitivity to x=0.07 in D mixing starts to become similar to the sensitivity of B^0_d mixing to new amplitudes.

For CP violation, the kaon system has a great advantage for detection of non-standard sources, because the lifetime splitting drags the CP- state out from under the CP+ state. If epsilon_K, which is of order x/1000 in the kaon system, is non-standard, one would expect to see the impact in the D system at x of 10^-5, and in the B system at x of 10^-4; this would be bad news, since CP violation at that level of x is probably undetectable, for either D's or B's.

Said another way: SUSY sources of CP violation might well appear superweak to us, if they couple universally to quarks.

However, there is no guarantee that the new SUSY physics is *universal* in its couplings to our quarks. However, there is no more reason that the new SUSY physics would favor the B system than it would favor the D system. So, for discovery potential, the D system is just as good as the B system.

There is one advantage to the D system: something new *might* be indicated by the *level* of mixing *alone*, because the Standard Model contribution is thought to be small. In the K and B systems, Standard Model mixing is large, so it tends to occlude the `new physics'.