The rising proton cross-section

Fast protons present a larger target in collisions, and RSI offers a physical reading of why.

In standard Einsteinian kinematics, Lorentz contraction is strictly longitudinal. An object shortens along its motion, while its transverse dimensions stay the same. Yet decades of collision data, including from the Large Hadron Collider (LHC), show that a proton's total interaction cross-section increases with energy. The cross-section measures how large a target the particle presents in collisions. The faster the proton travels, the wider it becomes as a target.

Standard physics does not see this as a conflict with relativity. It explains the growth by the cloud of gluons inside a fast proton becoming denser and reaching farther sideways, called at the highest energies the Color Glass Condensate. RSI gives that aura a physical geometry: the gluon is the braid's Shadow Junction, and the rising cross-section is read as the junction's reach growing with collision energy. It reflects how hard two braids strike one another, not a sideways bulging of the moving proton, whose width, in RSI as in relativity, is unchanged.