We study lattice g 0 φ 4 field theory for all g 0 and fixed renormalized mass M in one and two
dimensions using Monte Carlo techniques. We calculate the dimensionless renormalized …

The paradigm of the two-level atom is revisited and its perturbative analysis is discussed in
view of the principle of duality in perturbation theory. The models we consider are a two …

We derive the form of the infrared gluon propagator by proving a map** in the infrared of
the quantum Yang–Mills and λϕ4 theories. The equivalence is complete at a classical level …

Abstract Conventional weak-coupling Rayleigh-Schrödinger perturbation theory suffers from
problems that arise from resonant coupling of successive orders in the perturbation series …

I analyze numerically a two-dimensional λ ϕ 4 theory showing that in the limit of a strong
coupling λ→∞ just the homogeneous solutions for time evolution are relevant in agreement …

A difficult and long‐standing problem in mathematical physics concerns the determination of
the value of f (∞) from the asymptotic series for f (x) about x= 0. In the past the approach has …

It is argued that the approach to the crossover region from weak couplings is signaled by the
turn on of sizable tunneling effects. Numerically, this amounts to the necessity to include in …

We derive new all-purpose methods that involve the Dirac delta distribution. Some of the
new methods use derivatives in the argument of the Dirac delta. We highlight potential …

We determine the effective potential V [φ] in zero dimensional gφ 4 field theory when there is
broken symmetry classically [V cl= 1 4 g (φ 2− a 2) 2] as a power series in 1/g. We find that …

We describe a controllable and unbiased strong-coupling diagrammatic Monte Carlo
technique that is applicable to a wide range of fermionic systems and spin models. Unlike …