LHC upgrade scenarios

The EU CARE-HHH and US-LARP studies for an LHC luminosity upgrade aim at increasing the peak luminosity by a factor of 10, to 10³⁵ cm^-2 s^-1. The luminosity can be raised by rebuilding the interaction regions (IRs) in combination with a consistent change of beam parameters. In addition to advanced low-beta quadrupoles, the upgraded IRs may accommodate other new elements such as slim superconducting dipoles or quadrupoles embedded deep inside the detectors, global low-angle crab cavities, and wire compensators of long-range beam-beam effects. Important constraints on the upgrade path are the maximum acceptable number of detector pile-up events, favoring many closely spaced bunches, and the heat load on the cold-magnet beam screens, pointing towards fewer and more intense bunches. In order to translate the increased peak luminosity into a correspondingly higher integrated luminosity, the upgrade of the LHC ring should be complemented by an upgrade of the injector complex. I will present preferred upgrade scenarios for the LHC IRs including pertinent beam parameters, sketch accompanying injector enhancements, and briefly comment on a longer-term LHC energy upgrade.