Renormalization of the One Boson Exchange potential in the 1/Nc expansion

Alvaro Calle Cordon
University of Granada, Spain

In this talk I will analyze the renormalization of the NN interaction in 
the context of the Large Nc limit of QCD which has been received much 
less attention in the past as compared to the chiral approach. By using 
the dominant contributions in the 1/Nc expansion of the One Boson Exchange 
(OBE) potential old nuclear Wigner SU(4) and Serber symmetries can be 
understood as long distance symmetries. We proivde sum rules for phase 
shifts and Vlowk potentials which are satisfied phenomenologically and 
argue that they are in fact to be predictions of the large Nc expansion.

Moreover, we adress the problem of phenomenological strong form factors 
usually employed in the OBE. We show how invoking suitable boundary 
conditions, neutron-proton phase shifts and deuteron properties become 
largely insensitive to the form factors and to the vector mesons. Actually, 
reasonable agreement with low energy data for realistic values of the 
coupling constants (e.g. SU(3) values) is achieved providing a solution 
for a long-standing problem.

I will also present preliminary calculations analyzing the interplay 
between symmetry breaking and renormalization in the baryon-baryon system 
for s−waves, based in a short distance condition, where all pp,pn,nn and 
Coulomb phases and low energy parameters can successfully be related. 
Finally, some optimistic consequences of the renormalization of Meson 
Exchange Currents (MEC) are shown.