Progress on the soft anomalous dimension in QCD
TLDR
This paper reviews QCD IR singularities, presents a new lightcone expansion method for soft anomalous dimensions, and applies it to three-loop calculations.
Key contributions
- Reviews state-of-the-art knowledge on IR singularities and the simplicity of soft anomalous dimensions.
- Presents a novel strategy using lightcone expansion of Wilson line correlators via Method of Regions.
- Determined the three-loop soft anomalous dimension for single massive colored particles.
- Opens the path for computing this quantity for two heavy particles at three loops and beyond.
Why it matters
This paper significantly advances the computation of soft anomalous dimensions in QCD, which are essential for precise theoretical predictions in particle physics. The novel method simplifies complex calculations, enabling higher-order loop computations crucial for collider phenomenology.
Original Abstract
We review the state-of-the-art knowledge of IR singularities in multileg QCD amplitudes, identifying the key reasons for the remarkable simplicity of the soft anomalous dimension. We then present a novel strategy to compute this quantity using a lightcone expansion of correlators of semi-infinite Wilson lines by the Method of Regions. Recently, this strategy allowed us to determine the three-loop soft anomalous dimension for amplitudes consisting of a single massive coloured particle with any number of massless ones. It opens the way to computing this quantity for amplitudes involving two heavy particles at three loops and potentially going to higher loop orders.
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