New Standard for the Logarithmic Accuracy of Parton Showers

Area of Science:

• High-energy particle physics
• Quantum chromodynamics
• Computational physics

Background:

• Parton showers are essential for simulating high-energy particle collisions.
• Achieving higher logarithmic accuracy in parton showers is crucial for precise theoretical predictions.
• Event shapes are key observables for testing theoretical models of particle fragmentation.

Purpose of the Study:

• To achieve next-to-next-to-leading-logarithmic (NNLL) accuracy for event shape observables in parton showers.
• To establish a connection between analytic resummation techniques and parton shower calculations at NNLL accuracy.
• To numerically validate the logarithmic accuracy of different parton shower implementations.

Main Methods:

• Identification of the relationship between analytic NNLL resummation ingredients and parton shower counterparts.
• Development and implementation of parton shower algorithms incorporating NNLL accuracy.
• Numerical simulations of Z→qq[over ¯] and Higgs→gg decays for various event shape observables.

Main Results:

• Demonstration of NNLL accuracy in parton shower calculations for event shapes.
• Validation of the connection between analytic resummation and parton shower physics.
• Numerical tests confirm the logarithmic accuracy of three shower variants across multiple event shapes.

Conclusions:

• The achieved NNLL accuracy represents a significant advancement in the precision of parton shower event shape calculations.
• The findings facilitate more accurate comparisons between theoretical predictions and experimental data in high-energy physics.
• The phenomenological impact of NNLL terms is substantial, as shown by comparisons with experimental data.