Description
This document presents the executive summary of the findings of the Workshop on "The physics of HL-LHC, and perspectives on HE-LHC", which has run for over a year since its kick-off meeting on 30 October -- 1 November 2017.
We discuss here the HL-LHC physics programme. As approved today, this covers {\it (a)} pp collisions at 14~TeV with an integrated luminosity of 3 ab$^{-1}$ each for ATLAS and CMS, and 50 fb$^{-1}$ for LHCb, and {\it (b)} Pb--Pb and p--Pb collisions with integrated luminosities of 13 nb$^{-1}$ and 50 nb$^{-1}$, respectively. In view of possible further upgrades of LHCb and of the ions programme, the WG reports assume 300 fb$^{-1}$ of luminosity delivered to an Upgrade II of LHCb, 1.2 pb$^{-1}$ of integrated luminosity for p--Pb collisions, and the addition of collisions with other nuclear species.
A separate submission covers the HE-LHC results.
The activity has been carried out by five working groups (WGs): Standard Model'' (WG1),Higgs'' (WG2), Beyond the Standard Model'' (WG3),Flavour'' (WG4) and ``QCD matter at high density'' (WG5). Their reports, extending this executive summary with more results and details, are available on the CERN Document Server, and will appear on arXiv. The WG results include both phenomenological studies and detailed simulations of the anticipated performance of the LHC detectors under HL-LHC conditions. These latter studies implement the knowledge acquired during the preparation of the technical design reports for the upgraded detectors, and reflect the experience gained by the experiments during the first two runs of the LHC.
The documents describing in full detail the HL-LHC studies performed by the experiments are also available.
Three goals have been set for the Workshop: (i) to update and extend the projections for the precision and reach of the HL-LHC measurements, and for their interpretation; (ii) to highlight new opportunities for discovery of phenomena beyond the Standard Model (BSM), in view of the latest theoretical developments and of recent data; (iii) to explore possible new directions and/or extensions of the approved HL-LHC programme, particularly in the area of flavour, in the search for elusive BSM phenomena, and in the study of QCD matter at high density.
In addition to enriching and consolidating the physics plans for HL-LHC, and highlighting the significant advances that the full HL-LHC programme will bring relative to today's landscape, this contribution to the European Strategy for Particle Physics Update process is intended to help put in perspective the physics potential of future projects beyond HL-LHC.
