Real Interquark Potential Between a Heavy and a Light Quark at All   Distances
  We point out that in infinite spacetime dimensions, the singularity in the interquark potential at small distances disappears if the string is anchored at one end to a heavy quark, at the other end to a light quark. This suggests that if quarks are placed at the end of strings some unphysical features such as tachyon states may be absent also in in finite dimensions. 
H. Kleinert, G. Lambiase (Dipartimento di Fisica Teorica e S. M. S.   A., Universit\'a di Salerno), V.V. Nesterenko (Bogoliu...