# Theoretical Physics

Theoretical physics group (Altschul, Gudkov, Mazur, and Schindler) is involved with research in several areas of theoretical physics ranging from quantum aspects of gravity and cosmology, neutron physics and CP, P and T non-conservation in nuclear reactions to exotic physics from beyond the standard model such as breaking of Lorentz invariance.

The professor Altschul's research focuses on the possibility of exotic physics beyond the standard model of particle physics such as Lorentz symmetry breaking. He is working on astrophysical tests of relativity. This work concerns obtaining limits on Lorentz invariance violation (LIV) from synchrotron and inverse Compton sources, the limits on neutron LIV from pulsar timing.

Professor Gudkov is working on theoretical problems related to the experimental program in fundamental neutron physics at the SNS such as neutron beta-decay, parity and time reversal violation effects. This work is connected with the search for possible extensions of the standard model. His research subjects range from the applications of a neutron interferometric methods to subjects such as constraining non-Newtonian models of gravity at the nanometer scale, that has emerged as a result of phenomenological applications of string models, to scattering of ultracold neutrons on nano-size bubbles, neutron beta decay in effective field theory and CP-violation effects in nuclear reactions.

The professor Mazur's research focuses on quantum aspects of gravity and cosmology. His work on quantum mechanics of black holes and black hole thermodynamics has led to the theory of gravastars. Gravastars are ultra-cold and superdense thermally stable (positive heat capacity) macroscopic quantum objects that are the final state of gravitational collapse of matter. One may think of them as quantum superfluid droplets. It is the superfluid nature of gravastars that offers the signature distinguishing them from classical black holes. The present observational methods are reaching the limits that will allow to test the gravastar scenario for the final state of gravitational collapse. Mazur and his collaborators have also discovered the connection between quantum field theories on de Sitter space and conformal field theories (CFT) on the boundary, that is the so-called dS/CFT correspondence. Some applications of the dS/CFT results are the extension of the Harrison, Zeldovich and Peebles-Yu scaling in two-point correlations of the primordial density fluctuations, and in the microwave background radiation, to the general case of three-point and higher correlations.

Professor Schindler is working on problems in hadronic physics related to the strong and weak interactions. He has worked on theoretical methods to describe the properties of single protons and neutrons as well as the interaction between two and more nucleons. His current research focuses on fundamental symmetries in two- and few-nucleon systems. This work is related to ongoing experimental efforts at neutron facilities such as the Spallation Neutron Source at Oak Ridge National Laboratory.