Unquenched Flavor in the Gauge/Gravity Correspondence

Figure 4

We see on the left side the two stacks of 𝑁_𝑓 flavor-branes localized on each of their respective 𝑆²'s (they wrap the other 𝑆²). The flavor group is clearly 𝑈(𝑁_𝑓)×𝑈(𝑁_𝑓). After the smearing on the right side of the figure, this global symmetry is broken to 𝑈(1)^𝑁𝑓−1×𝑈(1)^𝑁𝑓−1×𝑈(1)_𝐵×𝑈(1)_𝐴.