HE-LHC beam-parameters, optics and beam-dynamics issues
  The Higher-Energy LHC (HE-LHC) should collide two proton beams of 16.5-TeV energy, circulating in the LHC tunnel. We discuss the main parameter choices, as well as some optics and beam dynamics issues, in particular the time evolution of emittances, beam-beam tune shift and luminosity, with and without controlled emittance blow up, considering various constraints, and the quadrupole-magnet parameters for arcs and interaction regions. 
O. Br\"uning, O. Dominguez, S. Myers, L. Rossi, E. Todesco, F.   Zimmermann (CERN)
physics.acc-ph