Is the graviton a domain wall glueball?

Recent developments in string theory have changed our perspective on the ancient puzzle on how to construct the QCD string. The conventional wisdom had been that the fundamental superstring for gravity operates exclusively at or near the the Planck scale with the extra 6 dimension compactified in Planckian units. The standard model (and therefore QCD) would appear as simply a low energy effective field theory long after all stringy effects have disappeared. In this scenario the fact that confinement of chromodynamic flux and the large N expansion might also exhibit stringy features is essentially accidental, with no physical relation to the strings of quantum gravity. With the discovery of Maldacena’s string/gauge duality [1], we now have explicit examples of the equivalence between 10-d superstring and 4-d Yang-Mills theory. The key new ingredient is a strongly “warped” radial (or 5-th) dimension as illustrated in the weak/strong duality between strings in AdS × S and 4-d N = 4 super Yang Mills. The redshift in the warped axis interpolates between low energy (IR) and high energy (UV) physics. Extensions of the string/gauge duality have been suggested by Witten [2] and others for non-SUSY QCD like theories exhibiting discrete glueball spectra, con-