CEEX EW Corrections for $f\bar{f}\rightarrow f'\bar{f'}$ at LHC and Muon Colliders as Realized in KK MC 4.22

With an eye toward the precision physics of the LHC and possible high energy muon colliders, we present the extension of the CEEX (coherent exclusive exponentiation) realization of the YFS approach to resummation in our KK MC to include the processes $f\bar{f}\rightarrow f'\bar{f'}$, $f=\mu,\tau,q,\nu_\ell, f'=e,\mu,\tau,q,\nu_\ell, q=u,d,s,c,b,t, \ell=e,\mu,\tau$ with $f\ne f'$. After giving a brief summary of the CEEX theory in comparison to the older EEX (exclusive exponentiation) theory, we illustrate theoretical results relevant to the LHC and possible muon collider physics programs.