4 citations · 6 across the 9 of their papers we have counts for
9 papers
Eliminating unphysical photon components from Dirac-Maxwell Hamiltonian quantized in the Lorenz gauge
Shinichiro Futakuchi, Kouta Usui
We study the Dirac-Maxwell model quantized in the Lorenz gauge. In this gauge, the space of quantum mechanical state vectors inevitably be an indefinite metric vector space so that…
Time-ordered exponential on the complex plane and Gell-Mann -- Low formula as a mathematical theorem
Shinichiro Futakuchi, Kouta Usui
The time-ordered exponential representation of a complex time evolution operator in the interaction picture is studied. Using the complex time evolution, we prove the Gell-Mann --…
New criteria for self-adjointness and its application to Dirac-Maxwell Hamiltonian
Shinichiro Futakuchi, Kouta Usui
We present a new theorem concerning a sufficient condition for a symmetric operator acting in a complex Hilbert space to be essentially self-adjoint. By applying the theorem, we pr…
Construction of dynamics and time-ordered exponential for unbounded non-symmetric Hamiltonians
Shinichiro Futakuchi, Kouta Usui
We prove under certain assumptions that there exists a solution of the Schrodinger or the Heisenberg equation of motion generated by a linear operator H acting in some complex Hilb…
On the spectra of fermionic second quantization operators
Shinichiro Futakuchi, Kouta Usui
We derive several formulae for the spectra of the second quantization operators in abstract fermionic Fock spaces.
A Note on Reflection Positivity and the Umezawa-Kamefuchi-Kallen-Lehmann Representation of Two Point Correlation Functions
Kouta Usui
It will be proved that a model of lattice field theories which satisfies (A1) Hermiticity, (A2) translational invariance, (A3) reflection positivity, and (A4) polynomial boundednes…
Direct Proof of Reflection Positivity of Free Overlap Dirac Fermion
Yoshio Kikukawa, Kouta Usui
It is shown that free lattice Dirac fermions defined by overlap Dirac operator fulfill the Osterwalder-Schrader reflection positivity condition with respect to the link-reflection.
Reflection Positivity of N=1 Wess-Zumino model on the lattice with exact U(1)_R symmetry
Yoshio Kikukawa, Kouta Usui
By using overlap Majorana fermions, the chiral multiple can be formulated so that the supersymmetry is manifest and the vacuum energy is cancelled in the free limit, t…
Reflection Positivity of Free Overlap Fermions
Yoshio Kikukawa, Kouta Usui
It is shown that free lattice fermions defined by overlap Dirac operator fulfill the Osterwalder-Schrader reflection positivity condition with respect to the link-reflection. The p…