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Two-loop divergences of QCD scattering amplitudes with massive partons
Andrea Ferroglia1, Matthias Neubert, Ben D Pecjak
1Institut für Physik (THEP), Johannes Gutenberg-Universität, D-55099 Mainz, Germany.
Physical Review Letters
|April 7, 2010
Summary
We describe two-loop infrared singularities in non-Abelian gauge theories. Our calculations reveal universal functions governing parton correlations, crucial for understanding particle interactions and mass effects.
Area of Science:
- High Energy Physics
- Quantum Field Theory
- Particle Physics
Background:
- Scattering amplitudes in non-Abelian gauge theories exhibit infrared singularities.
- Understanding these singularities is crucial for precise theoretical predictions in particle physics.
- Previous studies have focused on specific cases, necessitating a general framework.
Purpose of the Study:
- To provide a complete description of two-loop infrared singularities for scattering amplitudes.
- To analyze theories with arbitrary numbers of massive and massless partons.
- To determine the structure of three-parton correlations in the soft anomalous-dimension matrix.
Main Methods:
- Calculation of two universal functions defining the soft anomalous-dimension matrix at two-loop order.
- Derivation of these functions in closed analytic form.
- Analysis of the behavior of these functions in different kinematic regimes (small parton masses and near heavy particle pair production thresholds).
Main Results:
- Identified two universal functions that completely specify the structure of three-parton correlations.
- Demonstrated that these functions are suppressed as O(m^4/s^2) for small parton masses, consistent with mass factorization.
- Showed that the functions are unsuppressed near the threshold for heavy particle pair production.
Conclusions:
- The derived universal functions offer a comprehensive understanding of two-loop infrared singularities.
- The results provide crucial insights into the behavior of scattering amplitudes in various mass regimes.
- The application to qq -> tt near threshold reveals non-diagonal behavior in a specific basis, impacting theoretical predictions for heavy particle production.
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