- The paper introduces OneLOop, a tool that automates one-loop scalar function evaluation for NLO computations in collider physics.
- It details robust handling of UV and IR divergences via dimensional regularization to ensure reliable amplitude calculations.
- OneLOop implements scalar 1-, 2-, 3-, and 4-point functions in Fortran 77, enhancing integration with modern numerical libraries.
Overview of the OneLOop Program for Evaluating One-Loop Scalar Functions
The paper "OneLOop: for the evaluation of one-loop scalar functions" introduces a computational tool, OneLOop, devised to calculate scalar functions at the one-loop level, crucial for analyzing collider-physics phenomena at next-to-leading order (NLO) perturbation theory. This work, authored by A. van Hameren, offers an essential solution for computing one-loop scalar 1-point through 4-point functions, instrumental in determining virtual contributions within NLO calculations, particularly for processes involving multiple final-state particles.
Core Contributions
The development of OneLOop addresses significant computational challenges posed by one-loop integrals. These integrals are integral to the calculation of one-loop amplitudes necessary for the precision required in modern high-energy physics experiments, such as those conducted at the Large Hadron Collider (LHC). The tool effectively handles ultraviolet (UV) and infrared (IR) divergences using dimensional regularization—a method preferred for its systematic applicability in quantum chromodynamics (QCD) beyond tree-level approximations.
The paper highlights several key features of the OneLOop program:
- Versatility in Mass Configurations: The program accommodates all kinematic scenarios relevant for LHC physics, including varying complex internal mass configurations, which are imperative for accurately modeling unstable particles.
- Handling of Divergences: OneLOop robustly addresses IR and UV divergences, employing dimensional regularization to maintain the validity of amplitude calculations in singular scenarios.
- Routines for Numerical Integration: Included within OneLOop are routines that leverage numerical integration techniques for scalar function evaluation, serving both as a cross-validation mechanism for analytic continuations and for scenarios requiring verification of explicit implementations.
Technical Details and Implementation
OneLOop is implemented in Fortran 77, with compatibility for modern computational requirements such as long variable names and advanced control structures. The program's design facilitates straightforward integration with existing computational frameworks, either by direct compilation or through a more practical library construction using provided makefiles.
Key subroutines are available for evaluating scalar 1-point, 2-point, 3-point, and 4-point functions, including functions to compute Passarino-Veltman coefficients necessary for precise scattering amplitude calculations. The tool extends its utility by integrating with external libraries such as Cuba for numerical integration and Quadpack to bolster integration operation efficacy.
Theoretical and Practical Implications
The introduction and deployment of OneLOop in computational high-energy physics reinforce the analytical capacity to perform NLO QCD corrections—a critical requisite for discerning new physics against background processes in collider experiments. Moreover, by enabling the computation of complex-mass schemes, OneLOop aligns with the thoroughgoing needs of multi-particle decay processes, thereby contributing significantly to the collider phenomenology community.
In practical terms, OneLOop provides high-energy physicists with a reliable, adaptable tool to address the increasing demand for precise theoretical predictions, particularly as the scale and complexity of collider experiments evolve. Looking forward, extensions to integrating additional physical processes and increasing computational efficiency could be envisaged as future developments.
Conclusion
The OneLOop package is a significant step forward in automating the computation of one-loop scalar functions within dimensional regularization schemes. It is a crucial asset for theoretical and computational physicists engaged in high-precision particle physics. This contribution underpins both the current and future explorations of high-energy physics, facilitating the incisive exploration of fundamental forces and particles. The paper comprehensively documents the technical and theoretical foundations of OneLOop, ensuring that the program fulfills its role in the precision calculations essential for modern particle physics research.