Density matrix renormalization group (DMRG) is applied to a (1+1)dimensional Î»Ï†4 model. Spontaneous breakdown of discrete Z2 symmetry is studied numerically using vacuum wavefunctions. We obtain theâ€¦ (More)

For hamiltonian lattice gauge theory, we introduce the matr ix p oduct anzats inspired from density matrix renormalization group. In this method, wavefunction of the target state is assumed to be aâ€¦ (More)

An indication of spontaneous symmetry breaking is found in the twodimensional Î»Ï†4 model, where an attention is payed to a functional form of an effective action. An effective energy, which is anâ€¦ (More)

We study a (1+1)-dimensional lambda phi(4) model with a light-cone zero mode and constant external source to describe spontaneous symmetry breaking. In the broken phase, we find degenerate vacua andâ€¦ (More)

A method of Hamiltonian diagonalization is suitable for calculating physical quantities associated with wavefunctions, such as structure functions and form factors. However, we cannot diagonalizeâ€¦ (More)

The Gauss law needs to be imposed on quantum states to guarantee gauge invariance when one studies gauge theory in hamiltonian formalism. In this work, we propose an efficient variational methodâ€¦ (More)

In contrast with the great success of lattice gauge theory, lattice fermions remain a longstanding problem. Naive discretization causes the species doubling problem [1]. The situation does not changeâ€¦ (More)

We propose an efficient variational method for Z2 lattice gauge theory based on the matrix product ansatz. The method is applied to ladder and square lattices. The Gauss law needs to be imposed onâ€¦ (More)

The MCMC (Markov Chain Monte-Carlo) method [1] has played an important role in study of complex systems with many degrees of freedom. For example, MCMC has been applied to various many-body problemsâ€¦ (More)

Density matrix renormalization group (DMRG) is applied to a (1+1)-dimensional Î»Ï† model to study spontaneous breakdown of discrete Z2 symmetry numerically. We obtain the critical coupling (Î»/Î¼ 2)c =â€¦ (More)