Integrable Many-Particle Systems

Костянтин Вікторович Авдонін

Constructions of integral equations for the wave function of particle systems in bound states have been proposed in this work. We obtain the kernel of the Fredholm-type integral equation for an odd number of particles in explicit form. Besides, an integral equation that can be attributed to the class of Volterra integral equations was built. Their equivalence to known equations in limiting cases has been shown.

Philip L. Bowers

Zaijong Hwang

Among systems with many hard-core point particles that only interact by elastic collisions in one-dimension, it has long been thought that only those with equal mass particles were completely integrable, where the final state of the system through time evolution could be easily predicted from its initial state due to the existence of a maximal number of conserved quantities. In this thesis, we introduce a new class of integrable three-particle systems that contain two unequal masses. These integrable triplets can affect the rate of thermalization in a much larger system composed of particles with two unequal masses, the effect of which is demonstrated with a numerical simulation.

Ken‐ichi Amano

Path integral approaches have been used for boson and fermion systems. The path integral approach has been successful in the many-boson system. However, in the many-fermion system, the path integral approach is not feasible due to the sign problem. In this letter, I introduce additive particle (AP) theory in order to generate an approximation method that avoids the sign problem. The AP theory considers one electron as a string polymer, and virtual particles are added into the system. The AP theory is an approximation, but it is constructed to be able to generate the pair distribution function between free electrons and the density of states of the free electrons at an arbitrary temperature. Hence, when the electrostatic interactions are decreased, the AP theory converges to the free electron system. On the other hand, it deviates from the actual system when the electrostatic interactions are increased. Star polymer approximation and extended star polymer approximation are also introduced.

Lev Deych