Mark Hartman with Cyrus Taylor

Using the AdSICFT Correspondence to Predict Particle Masses in QCD

In the last two years, string theorists have been scrutinizing the implications of the so-called AdS/CFT (Anti deSitter space / conformal field theory) correspondence, one consequence of which is a duality between certain gauge theories in 4 dimensions and string theory (supergravity) on the space AdS^5 X S^5. This is a major step forward because it creates a relationship between the type of gauge theory that successfully describes electromagnetic, weak, and strong interactions, and the one force, gravity, that has failed to fit this general formula. A duality is defined as a one-to-one correspondence between quantities in the four-dimensional field theory and other quantities in the “stringy” picture of gravity. Exactly how deep this relationship extends is still unknown, but using this correspondence, one can gain insights into both of the theories on either side of the duality.

For example, in the AdS^5 X S^5 space, certain solutions of supergravity corresponding to the dynamics of a closed superstring yield discrete mass spectra that agree with the masses of glueballs. These particles, bound states of gluons (the particles that hold quarks together), are predicted by QCD, the 4-dimensional gauge theory that describes the strong interactions.

The first stage of this project is to complete an investigation which extends this line of thinking from the dynamics of closed strings to those of the simplest open strings in supergravity. It was thought the dynamics of this system would reproduce the mass spectrum for the lightest scalar and vector mesons: the pi and rho particles and their radial excitations. However, this prediction is not reproduced by the assumptions of our approach, but a clear statement of the AdS/CFT correspondence is revealed instead.

The second stage of this project involves taking a slightly different direction. The AdS/CFT correspondence is an example of the Holographic principle, according to which a quantum theory with gravity in d dimensions must be describable by a theory on its d-1

dimensional boundary. Either an extension of the first stage to include more complex particles or some other, closely-related aspect of the Holographic principle is to be investigated.