Speed of light isotropy and Lorentz violation bounds on the equilateral close-packed (face-centred cubic) lattice

Key Points

• This research aims to explore the isotropic nature of light speed and constraints on Lorentz violation within a face-centered cubic lattice framework.
• Analysis of lattice dispersion relations
• Application of O_h symmetry to determine group velocity
• Calculation of anisotropy at k^4 order
• Assessment of experimental Lorentz violation bounds
• Demonstrated isotropic group velocity of 1 in all directions
• Calculated anisotropy parameter c_4 as 1/144
• Confirmed five Lorentz violation bounds with varied margins from 10^5 to 10^52