Programme

P.17 -- Poster, VCTP-45

Date: Tuesday, 13 October 2020

Time: 08:30 - 10:00

Longitudinal excitations of the Heisenberg model: a functional integral approach

Nguyen Van Hinh (1), Pham Thi Thanh Nga (2) and Nguyen Toan Thang (3)

(1) Hanoi University of Industry, 298 Cau Dien, Bac Tu Liem, Hanoi, Vietnam (2) Thuyloi University, 175 Tay Son, Dong Da, Hanoi, Vietnam (3) Institute of Physics, 10 Dao Tan, Ba Dinh, Hanoi, Vietnam

We study the longitudinal excitations in the Heisenberg model by a functional integral approach. We represent the partition function of the quantum systems in terms of the functional integral over coherent Grassmann variables with Popov-Fedotov imaginary chemical for excluding non-physical states appeared due to transformations from spin operators to fermion ones. We go beyond the one-loop approximations taking into account coupling between transverse and longitudinal spin components. We compare our results with Xian’s ones, obtained on analogue to Feynmann’s theory on the low-lying excited states of the helium-4 superfluid (Y.Xian, Phys. Rev. B74 212401(2006)).

Presenter: Nguyen Van Hinh