Unquenched Flavor in the Gauge/Gravity Correspondence

Figure 1

Diagrams for a meson propagator, with two insertions of the meson operator (𝑛=2) shown as thick points on the boundaries. The dashed lines are gluons that fill the diagram in the large 𝑁_𝑐 limit and the thick lines are quarks. (a) Planar diagram with no internal quark loops (ℎ=0, 𝑤=0), the scaling is ∼1. (b) Planar diagram with an internal quark loop ℎ=0, 𝑤=1, the scaling is ~𝑁_𝑓/𝑁_𝑐. (c) Nonplanar diagram with no internal quark loops ℎ=0, 𝑤=0, 𝑏=2, the scaling is ∼1/𝑁_𝑐.

(a)

(b)

(c)