Astrophysical Limits on Lorentz Violation for Pions

Understand

Pions, like nucleons, are composed primarily of up and down quarks and gluons.

• Constraints on spin-independent Lorentz violation in the proton, neutron, and pion sectors translate into bounds on Lorentz violation for the fundamental fields.
• The best bounds on pion Lorentz violation come from astrophysical measurements.
• The absence of the absorption process gamma --> pi^(+) + pi^(-) for up to 50 TeV photons constrains the possibility that pions' maximum achievable velocities are less than 1 at the 1.5 x 10^(-11) level.