Impact of Nb$_{3}$Sn Dipoles on the LHC Lattice and Beam Optics

In view of the LHC operation at full energy (7 TeV) as well as in preparation for the HL-LHC luminosity upgrade an improved collimation system is planned, which foresees additional collimators in the dispersion suppressor region of the ring. To deliver the space needed in the cold part of the LHC lattice the use of new, stronger dipole magnets based on Nb$_{3}$Sn technology is proposed to deliver room for the new collimators. Based on field calculations and assumptions for their multipole content the impact of these new magnets on the machine optics, the lattice design and finally the dynamic aperture is discussed. Persistent currents especially at low field play an essential role and accordingly additional multipole corrector coils might be needed to compensate the field errors at LHC injection energy and the low part of the acceleration procedure. The calculations presented here give estimates for the "allowed" multipole tolerances of the new magnets and propose - where needed - the installation of spool piece correctors to compensate the imperfections locally, using the dynamic aperture as a key parameter for the allowed field imperfections.