On non-local representations of the ageing algebra

TL;DR

This paper introduces new non-local representations of the ageing algebra for systems with dynamical exponent z=n, expanding the understanding of symmetries in non-equilibrium ageing phenomena.

Contribution

It constructs and analyzes non-local representations of the ageing algebra for arbitrary integer z=n, including explicit transformations and two-point functions.

Findings

Derived non-local symmetry representations for z=n.

Computed two-point functions with distinct forms for even and odd n.

Identified decay behaviors of scaling functions depending on mass parameter sign.

Abstract

The ageing algebra is a local dynamical symmetry of many ageing systems, far from equilibrium, and with a dynamical exponent z=2. Here, new representations for an integer dynamical exponent z=n are constructed, which act non-locally on the physical scaling operators. The new mathematical mechanism which makes the infinitesimal generators of the ageing algebra dynamical symmetries, is explicitly discussed for a n-dependent family of linear equations of motion for the order-parameter. Finite transformations are derived through the exponentiation of the infinitesimal generators and it is proposed to interpret them in terms of the transformation of distributions of spatio-temporal coordinates. The two-point functions which transform co-variantly under the new representations are computed, which quite distinct forms for n even and n odd. Depending on the sign of the dimensionful mass parameter, the two-point scaling functions either decay monotonously or in an oscillatory way towards zero.