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Selected Works

Conformal field theories

Publication Year

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Full-Text Articles in Physics

Universality And A Generalized C-Function In Cfts With Ads Duals, D. Klemm, A.C. Petkou, George Siopsis, D. Zanon Jan 2002

Universality And A Generalized C-Function In Cfts With Ads Duals, D. Klemm, A.C. Petkou, George Siopsis, D. Zanon

George Siopsis

We argue that the thermodynamics of conformal field theories with AdS duals exhibits a remarkable universality. At strong coupling, a Cardy–Verlinde entropy formula holds even when R-charges or bulk supergravity scalars are turned on. In such a setting, the Casimir entropy can be identified with a generalized C-function that changes monotonically with temperature as well as when non-trivial bulk scalar fields are introduced. We generalize the Cardy–Verlinde formula to cases where no subextensive part of the energy is present and further observe that such a formula is valid for the N=4 source super Yang–Mills ...


Entropy Bounds, Monotonicity Properties And Scaling In Cfts, D. Klemm, A.C. Petkou, George Siopsis May 2001

Entropy Bounds, Monotonicity Properties And Scaling In Cfts, D. Klemm, A.C. Petkou, George Siopsis

George Siopsis

We study the ratio of the entropy to the total energy in conformal field theories at finite temperature. For the free field realizations of N=4 source super Yang–Mills theory in D=4 and the (2,0) tensor multiplet in D=6, the ratio is bounded from above. The corresponding bounds are less stringent than the recently proposed Verlinde bound. We show that entropy bounds arise generically in CFTs in connection to monotonicity properties with respect to temperature changes of a generalized C-function. For strongly coupled CFTs with AdS duals, we show that the ratio obeys the Verlinde ...


Temperature Of D3-Branes Off Extremality, Suphot Musiri, George Siopsis Apr 2001

Temperature Of D3-Branes Off Extremality, Suphot Musiri, George Siopsis

George Siopsis

We discuss non-extremal rotating D3-branes. We solve the wave equation for scalars in the supergravity background of certain distributions of branes and compute the absorption coefficients. The form of these coefficients is similar to the gray-body factors associated with black-hole scattering. They are given in terms of two different temperature parameters, indicating that fields (open string modes) do not remain in thermal equilibrium as we move off extremality. This should shed some light on the origin of the disagreement between the supergravity and conformal field theory results on the free energy of a system of non-coincident D-branes.