2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/185703Within the framework of the Gaussian wave-functional approach, we investigate the influences of quantum and finite-temperature effects on the Z_2-symmetry(ϕ\to -ϕ) of the (1+1)-dimensional massive sine-Gordon field theory. It is explicitly demonstrated that by quantum effects the Z_2-symmetry can be restored in one region of the parameter space and dynamically spontaneously broken in another region. Moreover, a finite-temperature effect can further restore the Z_2-symmetry only.12 pages, 14 figures (EPS)High Energy Physics - Theorytext