Generalized Virial Identities: Radial Constraints for Solitons, Instantons, and Bounces

TL;DR

This paper introduces a family of virial identities for symmetric field configurations, enabling detailed analysis of solitons, instantons, and bounces by decomposing global constraints into radial components.

Contribution

The authors develop a systematic method of virial identities parameterized by an exponent, providing new insights into the structure of various topological and non-topological solutions.

Findings

Analytical verification for Fubini-Lipatov instanton, BPS monopole, and BPST instanton.

Numerical tests on Coleman bounce and Nielsen-Olesen vortex reveal error growth patterns related to core and tail inaccuracies.

Application to electroweak sphaleron and Skyrmion demonstrates the formalism's versatility in multi-scale systems.

Abstract

We derive a continuous family of virial identities for O($n$) symmetric configurations, parameterized by an exponent $\alpha$ that controls the radial weighting. The family provides a systematic decomposition of the global constraint into radially-resolved components, with special $\alpha$ values isolating specific mechanisms. For BPS configurations, where the Bogomolny equations imply pointwise equality between kinetic and potential densities, the virial identity is satisfied for all valid $\alpha$. We verify the formalism analytically for the Fubini-Lipatov instanton, BPS monopole, and BPST instanton. Numerical tests on the Coleman bounce and Nielsen-Olesen vortex illustrate how the $\alpha$-dependence of errors distinguishes core from tail inaccuracies: the vortex shows errors growing at negative $\alpha$ (core), while the bounce shows errors growing at positive $\alpha$ (tail). Applications to the electroweak sphaleron, where the Higgs mass explicitly breaks scale invariance, and the hedgehog Skyrmion illustrate the formalism in systems with multiple competing length scales.