This series consists of talks in the area of Superstring Theory.
We derive the collective theory of singlet fields of large-N Sp(N) spin
models and display its unconventional features. Using the known relationship
between O(N) collective fields and higher spin fields of Vasiliev theory in AdS
space, we argue that the unique features of the Sp(N) collective
theory suggest an interpretation in terms of a higher spin theory in de Sitter
space, as proposed by Anninos, Hartman and Strominger. This is
reminiscent of the way the Liouville mode is naturally interpreted as
When nuclear matter is heated beyond a temperature of 2 trillion
degrees, it converts into a strongly coupled plasma of quarks and
gluons, the sQGP. Experiments using highly energetic collisions
between heavy nuclei have revealed that this new state of matter is a
nearly ideal, highly opaque liquid. A description based upon string
theory and black holes in five dimensions has made the quark- gluon
plasma an iconic example of a strongly coupled quantum system. In this
Knowledge of all-alpha' higher derivative corrections to leading order BPS and non-BPS brane actions would serve in future endeavor of determining the complete form of the non-abelian BPS and tachyonic effective actions. In this talk, we note that there is a universality in the all-alpha' order corrections to BPS and non-BPS branes. I talk about computing all amplitudes between one Ramond-Ramond C-field vertex operator and several SYM gauge/scalar vertex operators.
We add a gravitational background lattice to the simplest holographic model of matter at finite density and calculate the optical conductivity. With the lattice, the zero frequency delta function found in previous calculations (resulting from translation invariance) is broadened and the DC conductivity is finite. The optical conductivity exhibits a Drude peak with a cross-over to power-law behavior at higher frequencies. Surprisingly, these results bear a strong resemblance to the properties of some of the cuprates.
A local renormalization group procedure is proposed where length scale is changed in spacetime dependent manner. Combining this scheme with an earlier observation that high energy modes in renormalization group play the role of dynamical sources for low energy modes at each scale, we provide a prescription to derive background independent holographic duals for field theories.
It is well known that on-shell recursion relation can be applied to tree-level amplitude in string theory. One technical issue of the application is the sum of infinite middle on-shell states. We discuss how we can do the sum exactly to reproduce the known result.