Multiparametric response of the HL-LHC Dynamic Aperture in presence of beam-beam effects

We performed extended simulations of HL-LHC dynamic aperture in the presence of beam-beam effects in the weak-strong approximation, evaluating the contributions of parameters such as: bunch intensity, crossing angle, chromaticity, current in the Landau octupoles and multipole errors. From the beam dynamics point of view, the main difference between the LHC (until 2017) and the HL-LHC is the deployment of the achromatic telescopic squeezing (ATS) optics, allowing not only for a smaller beta* reach, but also modifying the phase advances between the lattice correctors (sextupoles, octupoles) and the main IPs, and increasing the peak beta functions in the arcs. These correctors become therefore more efficient for the chromatic correction, but also a mitigation of the beam-beam long range interactions using the Landau octupoles is enabled, resulting in a possible reduction of the normalised crossing angle. The limits have been investigated in a tracking simulation campaign aimed at exploring the operational space for the HL-LHC and two possible options for luminosity levelling.