Session Y02: The High Luminosity LHC Upgrade and New Physics Windows

Physics at the HL-LHC

The High Luminosity (HL) LHC will start around 2026 with an expected integrated luminosity of 3 ab-1 and a mean number of proton-proton collisions per bunch crossing or pileup of about 200. Both the ATLAS and CMS experiments have planned upgrades to obtain performance similar to or exceeding that of Run-1 but in this challenging high pileup environment. This talk summarizes the expected performance in reconstructing physics objects such as jets, muons, electrons, taus, photons, and missing transverse momentum. The expected physics measurements from the large HL-LHC dataset including searches for beyond the Standard Model particles, Higgs measurements, and Standard Model particle measurements are also shown.   

Tracking at the HL-LHC

The High Luminosity Large Hadron Collider (HL-LHC) will increase the instantaneous luminosity from 2x10$^{\mathrm{34}}$ cm$^{\mathrm{-2}}$s$^{\mathrm{-1}}$ to 7.5x10$^{\mathrm{34}}$ cm$^{\mathrm{-2}}$s$^{\mathrm{-1}}$ with an expected lifetime total integrated luminosity up to 4,000 fb$^{\mathrm{-1}}$. To achieve this requires working in a more challenging environment to disentangle the hard-scatter event of interest from the average 200 additional pileup interactions expected in each event. ATLAS and CMS will both install a new tracking detector prior to the start of the HL-LHC extending the tracking coverage out to pseudorapidity of 4. The trackers will be key to maintaining and improving upon current performance in the harsh pileup environment. The individual designs were optimized to maintain track reconstruction efficiencies while reducing the overall mass of the detector. The tracking will be a critical element to mitigate pileup effects and enable a broader physics impact. The expected tracking performance and subsequently vertexing and b-tagging performance at the HL-LHC will be presented for both ATLAS and CMS.   

Calorimetry at the HL-LHC

The Large Hadron Collider (LHC) is currently providing proton-proton collisions at the world's highest center-of-mass energy. The High-Luminosity LHC (HL-LHC), scheduled to start in 2026, is planned to collect an integrated luminosity in excess of 3/ab, and provide the opportunity to perform precise measurements of Higgs properties, and search for new physics beyond the standard model. Calorimeters are pivotal elements of the detectors that will exploit these data samples. The running conditions, particularly the increase in average number of proton-proton collisions per bunch crossing (“pile-up”) and in the rate at which events are recorded, pose stringent constraints on their performance requirements. I will present an overview of the HL-LHC upgrade plans for the ATLAS and CMS calorimeters, with a focus on how their designs meet the challenges of HL-LHC operations, and show some of the ongoing R&D that demonstrates that they will satisfy the requirements imposed by the HL-LHC physics program.