Quantum broadening of k-strings from the AdS/CFT correspondence

We study the quantum broadening (width) of k-strings. We generalise an old result by Lüscher, Münster and Weisz to the case of a k-string, by using the gauge/gravity correspondence. When the fundamental QCD-string is replaced by a bound state of k strings, the bound state is better described by a wrapped D-brane. We calculate the width of the k-string (the wrapped D-brane) in several AdS/CFT backgrounds by using a D-brane probe and find universally that ωk2=12πσklogR/r.