Non-Local Classical Field Theory with Fractional Operators on $\mathbb{S}^3 \times \mathbb{R}^1$ Space

TL;DR

This paper develops a new non-local classical field theory framework on the space   with fractional operators, addressing symmetry issues and deriving field equations via a variational principle.

Contribution

Introduction of novel fractional operators on   space that preserve spacetime symmetries and facilitate non-local field theory formulation.

Findings

New fractional operators over   space introduced.

Field equations derived from a non-local variational principle.

Framework accounts for Lorentzian spacetime symmetries.

Abstract

We present a theoretical framework on non-local classical field theory using fractional integrodifferential operators. Due to the lack of easily manageable symmetries in traditional fractional calculus and the difficulties that arise in the formalism of multi-fractional calculus over $\mathbb{R}^{\text{D}}$ space, we introduce a set of new fractional operators over the $\mathbb{S}^3 \times \mathbb{R}^1$ space. The redefined fractional integral operator results in the non-trivial measure canonically, and they can account for the spacetime symmetries for the underlying space $\mathbb{S}^3 \times \mathbb{R}^1$ with the Lorentzian signature $(+, -, -, -, -)$. We conclude that the field equation for the non-local classical field can be obtained as the consequence of the optimisation of the action by employing the non-local variations in the field after defining the non-local Lagrangian density, namely, $\mathcal{L}(\phi_{a}\left(x\right), \mathbb{\eth}^\alpha \phi_{a}\left(x\right))$, as the function of the symmetric fractional derivative of the field, e.g. in the context of the kinetic term, and the field itself.