Testing Lorentz Symmetry with Lunar Laser Ranging

Area of Science:

• * Theoretical physics, specifically focusing on Lorentz symmetry and effective field theories.
• * Astrophysics and observational cosmology, utilizing celestial mechanics and ranging data.

Background:

• * The Standard-Model Extension (SME) framework allows for parametrization of Lorentz symmetry violations by incorporating general relativity and the Standard Model of particle physics.
• * Previous studies have used various methods, including binary pulsar and lunar laser ranging (LLR) observations, to constrain SME coefficients.

Purpose of the Study:

• * To derive new constraints on pure gravity SME coefficients using a comprehensive analysis of LLR observations.
• * To compare the sensitivity of LLR data to different linear combinations of SME coefficients than previously analyzed.

Main Methods:

• * Utilized a new numerical lunar ephemeris computed within the SME framework.
• * Analyzed a dataset of 20,721 LLR normal points spanning from August 1969 to December 2013.
• * Performed a data analysis focusing on specific linear combinations of SME coefficients.

Main Results:

• * Established new upper bounds on several pure gravity SME coefficients, including limits at the 10^{-8} to 10^{-12} level.
• * Demonstrated that LLR data are sensitive to different combinations of SME coefficients compared to prior analyses.
• * Achieved significant improvements in constraints, up to factors of 5 and 800 compared to previous binary pulsar and LLR analyses, respectively.

Conclusions:

• * The study found no evidence for Lorentz violation within the analyzed data, setting new stringent limits.
• * The improved constraints contribute to a better understanding of fundamental physics and the validity of Lorentz symmetry.
• * LLR observations offer a powerful tool for probing fundamental physics beyond the Standard Model.