The SU(2) instanton and the adiabatic evolution of two Kramers doublets
نویسندگان
چکیده
The adiabatic evolution of two doubly-degenerate (Kramers) levels is considered. The general five-parameter Hamiltonian describing the system is obtained and shown to be equivalent to one used in the Γ8 ⊗ (τ2 ⊕ ǫ) JahnTeller system. It is shown explicitly that the resulting SU(2) non-Abelian geometric vector potential is that of the (SO(5) symmetric) SU(2) instanton. Various forms of the potentials are discussed.
منابع مشابه
On the lattice construction of electroweak gauge theory
Based on the Ginsparg-Wilson relation, a gauge invariant formulation of electroweak SU(2)×U(1) gauge theory on the lattice is considered. If the hypercharge gauge coupling is turned off in the vacuum sector of the U(1) gauge fields, the theory consists of four left-handed SU(2) doublets and it is possible, as in vector-like theories, to make the fermion measure defined globally in all topologic...
متن کاملLocal adiabatic mixing of Kramers pairs of Majorana bound states.
We consider Kramers pairs of Majorana bound states under adiabatic time evolution. This is important for the prospects of using such bound states as parity qubits. We show that local adiabatic perturbations can cause a rotation in the space spanned by the Kramers pair. Hence, the quantum information is unprotected against local perturbations, in contrast to the case of single localized Majorana...
متن کاملSymmetry remnants: Rationale for having two Higgs doublets.
There is a good reason why the standard electroweak SU(2) × U(1) gauge model may be supplemented by two Higgs scalar doublets. They may be remnants of the spontaneous breaking of an SU(2) × SU(2) × U(1) gauge symmetry at a much higher energy scale. In one case, the two-doublet Higgs potential has a custodial SU(2) symmetry and implies an observable scalar triplet. In another, a light neutral sc...
متن کاملOptical properties of silicon nano layers by using Kramers- Kronig method
Silicon thin layers are deposited on glass substrates with the thickness of 103 nm, 147 nm and 197 nm. The layers are produced with electron gun evaporation method under ultra-high vacuum condition. The optical Reectance and the Transmittance of produced layers were measured by using spectrophotometer. The optical functions such as, real and imaginary part of refractive index, real and imaginar...
متن کاملMagnetically hidden order of Kramers doublets in d;{1} systems: Sr2VO4.
We formulate and study an effective Hamiltonian for low-energy Kramers doublets of d;{1} ions on a square lattice. We find that the system exhibits a magnetically hidden order in which the expectation values of the local spin and orbital moments both vanish. The order parameter responsible for a time-reversal symmetry breaking has a composite nature and is a spin-orbital analog of a magnetic oc...
متن کامل