Alternative scenarios for the LHC based electron-proton collider

Construction of the ERLC (twin LC) collider tangential to LHC will allow investigating ep collisions at essentially higher center-of-mass energies than ERL-50 and LHC based ep collider. Luminosity estimations show that values well exceeding 10 34 cm-2s-1 - 2 s - 1 can be achieved for ERLC and HL-LHC based ep colliders. Certainly, proposed ep colliders have great potential for clarifying QCD basics and new physics search in addition to providing precise PDFs for adequate interpretation of the LHC experimental data. Another alternative to the ERL-50 is to construct an e-ring with the same energy and length. In this case, luminosity of order 1034cm-2s-1 34 cm - 2 s - 1 can be reached. The advantage of this option is that the mu -ring can be installed instead of the e-ring as a next stage, which will allow to reach a much higher center of mass energy.