Dynamics of Baryons from String Theory and Vector Dominance

Understand

We consider a holographic model of QCD from string theory, a la Sakai and Sugimoto, and study baryons.

• In this model, mesons are collectively realized as a five-dimensional \$U(N_F)=U(1)\times SU(N_F)$ Yang-Mills field and baryons are classically identified as $SU(N_F)$ solitons with a unit Pontryagin number and $N_c$ electric charges.
• The soliton is shown to be very small in the large 't Hooft coupling limit, allowing us to introduce an effective field ${\cal B}$.
• Its coupling to the mesons are dictated by the soliton structure, and consists of a direct magnetic coupling to the $SU(N_F)$ field strength as well as a minimal coupling to the $U(N_F)$ gauge field.