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arXiv · 2312.05957

Revisiting the time-ordering issue of TMD soft factors: causality, coordinate space analyticity and new equalities

Yizhuang Liu
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Abstract

We show that as a result of causality-constrained coordinate space analyticity, the Drell-Yan-shape transverse-momentum dependent soft factor in the exponential regulator allows Euclidean-type parametric representations without cuts, to all orders in perturbation theory. Moreover, it is identical to another soft factor defined with a single time-ordering that has a natural interpretation as a space-like form factor. Furthermore, this relation continues to hold for a larger class of TMD soft factors that interpolate between three different rapidity regulators: the off-light-cone regulator, the finite light-front length regulator, and the exponential regulator.

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Yizhuang Liu. 2023-12-10. Revisiting the time-ordering issue of TMD soft factors: causality, coordinate space analyticity and new equalities. https://doi.org/10.1007/jhep09(2024)030

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