عنوان

Nonperturbative studies of scalar and scalar-fermion quantum field theories at zero and finite temperature using the Gaussian effective potential

TLpq303679514

انگلیسی

Nonperturbative studies of scalar and scalar-fermion quantum field theories at zero and finite temperature using the Gaussian effective potential

[Thesis]

G. A. Hajj

P. M. Stevenson

Rice University

1988

159

Ph.D.

Rice University

1988

The Gaussian effective potential (GEP), a non-perturbative approach to study quantum field theory, is applied to scalar and scalar-fermion models. We study the scalar usd\phi\sp6usd field coupled to fermions through g{\rm B}\phi\overline{\psi}\psi or g{\rm B}\phi\sp2\overline{\psi}\psi in 2 and 3 space-time dimensions. In addition, we derive the finite temperature (T > 0) GEP from first principles and apply it to study these models at T > 0. Also the Autonomous usd\lambda\phi\sp4usd, coupled to fermions through a Yukawa term (g{\rm B}\phi\overline{\psi}\psi), is examined in 4 dimensions at T > 0. In all these models, in order to obtain stable theories, it is found that gB must vanish as 1/log(Muv), 1/Muv or 1/Msp{\rm uv}{2} in 2, 3 or 4 dimensions respectively, Muv being an ultraviolet cutoff which is sent to infinity. The contribution of fermions to the GEP, however, is nonvanishing. It is also found that for the class of theories discussed, symmetry, if broken, is restored above a critical temperature. The coupling constant parameter space for each model is studied carefully, and regions where symmetry breaking occurs are determined both at zero and finite temperature.

Particle physics

Pure sciences

G. A. Hajj

P. M. Stevenson

p

[Thesis]

276903

a

Y