Continuation In Coupling Constant Research Articles

On the calculation of resonances by means of analytic continuation in coupling constant

The method of analytic continuation in the coupling constant in combination with the use of statistical Padé approximation designed to determine resonance parameters is introduced. It is shown that standard quantum chemistry codes provide accurate data which can be used for the process of analytic continuation in coupling constant. Resonance parameters, both the energy and the width, can be inferred for real molecules with accuracy comparable to other more elaborated methods.

Low-lying resonances of 9ΛBe: Faddeev calculation with Padé-approximants

Configuration space Faddeev equations are applied to describe the 9ΛBe hypernucleus in the ααΛ cluster model. For calculation of resonance state energies a variant of the method of analytical continuation in coupling constant is used. To realize this method, an auxiliary three-body potential is added to the Hamiltonian of the equations. A proper choice of strength parameter of the potential converts a resonance state into a bound state and an energy trajectory is obtained by variations of this parameter. To fulfill analytical continuation of this trajectory as a function of the strength parameter onto the complex plane, the Pade approximation is used. Spectrum of low-lying resonances is calculated with two αΛ phenomenological potentials. We predict existence of the 0+2 and 4+1 virtual states as well as the 2+2 resonance state near by the ααΛ threshold. The Be 8 ( L + ) + Λ ( s -wave ) configuration for description of the 9ΛBe ground band is discussed.

Failure of strong asymptotic conditions in four‐dimensional field theories

AbstractIt is shown that the renormalization group imposes severe restrictions on analytic continuation in coupling constant in the case of field theories in four dimensions.

Description of few-body systems via analytical continuation in coupling constant

The method of analytical continuation using the Pade approximant technique in the total and partial coupling constants is described and illustrated with some examples. The method can be applied to calculate the characteristics of the loose near-threshold and few-body resonance states in the case of the potential with a strong repulsive core etc.