Pseudo-Goldstone excitations in chiral Yukawa-theories with quadratic explicit symmetry breaking

Abstract

The symmetry breakdown pattern is studied in models containing one fermion flavor multiplet and a multicomponent scalar field, supplemented with a chiral Yukawa-interaction, and in presence of an explicit symmetry breaking source quadratic in the scalar field. In a detailed investigation of the model with $U_L(1)\times U_R(1)$ chiral symmetry it is shown that by diminishing the strength of quadratic explicit symmetry breaking one can still keep stable the mass ratio of the fermionic and the pseudo-Goldstone excitation. At the same time the mass ratio of the two bosonic excitations appears to approach a limiting value depending only on the infrared value of the first ratio, but not on the microscopic (ultraviolet) coupling values. The observations receive a general interpretation by the existence of an ultraviolet fixed point located in the symmetric phase. Understanding the general conditions for its existence allows the construction of a similar theory with $U_L(2)\times U_R(2)$ chiral symmetry. All results of the present investigation were obtained with nonperturbative functional renormalisation group technique making use of the first two approximations to the gradient expansion of the effective action.

21 pages, 11 figures

References in corpus (10)

• Exact evolution equation for the effective potential
• Asymptotic safety guaranteed
• Asymptotic safety: a simple example
• Directions for model building from asymptotic safety
• Lower Higgs boson mass bounds from a chirally invariant lattice Higgs-Yukawa model with overlap fermions
• Radiative symmetry breaking from interacting UV fixed points
• Non-Gaussian fixed points in fermionic field theories without auxiliary Bose-fields
• A lattice study of a chirally invariant Higgs-Yukawa model including a higher dimensional ${\Phi }^6$-term
• Dynamical fermion mass generation by a strong Yukawa interaction
• Dynamical breakdown of Abelian gauge chiral symmetry by strong Yukawa interactions

Cited by in corpus (2)

• Scheme dependence of asymptotically free solutions
• Asymptotic freedom in $Z_2$-Yukawa-QCD models