Proton colliders at the energy frontier

Abstract

Since the first proton collisions at the CERN Intersecting Storage Rings (ISR) [1,2], hadron colliders have defined the energy frontier [3]. Noteworthy are the conversion of the Super Proton Synchrotron (SPS) [4,5] into a proton-antiproton collider, the Tevatron proton-antiproton collider [6], as well as the abandoned SSC in the United States [7,8], and early forward-looking studies of even higher-energy colliders [9,10,11,12]. Hadron colliders are likely to determine the pace of particle-physics progress also during the next hundred years. Discoveries at past hadron colliders were essential for establishing the so-called Standard Model of particle physics. The world's present flagship collider, the Large Hadron Collider (LHC) [13], including its high-luminosity upgrade (HL-LHC) [14], is set to operate through the second half of the 2030's. Further increases of the energy reach during the 21st century require another, still more powerful hadron collider. Three options for a next hadron collider are presently under investigation. The Future Circular Collider (FCC) study, hosted by CERN, is designing a 100 TeV collider, to be installed inside a new 100 km tunnel in the Lake Geneva basin. A similar 100-km collider, called Super proton-proton Collider (SppC), is being pursued by CAS-IHEP in China. In either machine, for the first time in hadron storage rings, synchrotron radiation damping will be significant, with a damping time of the order of 1 hour. In parallel, the synchrotron-radiation power emitted inside the cold magnets becomes an important design constraint. One important difference between FCC and SppC is the magnet technology. FCC uses 16 Tesla magnets based on Nb3Sn superconductor, while SppC magnets shall be realized with cables made from iron-based hightemperature superconductor. Initially the SppC magnets are assumed to provide a more moderate dipole field of 12 T, but they can later be pushed to a final ultimate field of 24 T. A third collider presently under study is the High-Energy LHC (HE-LHC), which is a higher energy collider in the existing LHC tunnel, exploiting the FCC magnet technology in order to essentially double the LHC energy at significantly higher luminosity.

Left-right SU(4) vector leptoquark model for flavor anomalies

“…The leptoquark model file for MadGraph was implemented using FeynRules [64] (version 2.3.32). Figure 1 plots the number of background (B) and signal (S) events for a leptoquark mass 10, 12 and 14 TeV expected within the first year of FCC running (estimated to be 250 fb −1 of data [65]) as a function of the invariant mass of the highest transverse momentum jet j and µ + . Implementing the invariant mass cut | M jµ + −M X L | < Γ X , where Γ X is the width of the leptoquark, the significance of the signal, S/ √ B, is very high: 19 σ for M X L = 10 TeV, 6.7 σ for 12 TeV and 4.5 σ for 14 TeV.…”

Average event properties from LHC to FCC-hh

“…The central scale choice used is the default in MG5 aMC@NLO, namely half the sum of transverse masses over all particles m T 2 (equivalent to H T /2 for massless particles). In addition we provide predictions for two choices of PDF set, namely NNPDF 2.3 (which 7 In [13] there were some inconsistencies in the setup for the predictions of pT between that described in the main text and that shown on the plot; we find agreement if we use the setup shown on the plot. 8 Scale variations were performed using the conventional method of 7-point variation.…”

“…The long-term future of physics at the energy frontier is looking increasingly towards designs of pp colliders operating at CM energies of up to 100 TeV (FCC-hh or SppC) [1][2][3][4][5][6]. In the context of detector design efforts and basic phenomenology studies for such machines, as well as for the 14-TeV LHC and 27-TeV HE-LHC options, a set of predictions (or, at the very least, extrapolations) are required for elementary quantities characterising event properties such as overall rates (total and inelastic cross sections), tracker occupancies (charged-track densities) and total energy depositions (dE/dη).…”

“…In the context of detector design efforts and basic phenomenology studies for such machines, as well as for the 14-TeV LHC and 27-TeV HE-LHC options, a set of predictions (or, at the very least, extrapolations) are required for elementary quantities characterising event properties such as overall rates (total and inelastic cross sections), tracker occupancies (charged-track densities) and total energy depositions (dE/dη). Going beyond predictions for single events, superpositions of minimumbias events are also used to estimate the dependence of the overall activity on the number of events per bunch crossing (pile-up), which is projected to reach O(1000) for peak luminosities of 3 × 10 35 cm −2 s −1 targeted at both HE-LHC and FCC-hh [6,7].…”

Some Key Issues of Vacuum System Design in Accelerators and Colliders

“…Key parameters for CEPC [29], FCC-hh [30], FCC-ee [26,31], HE-LHC [30,32], HL-LHC [30], and LHC(pp) [29].…”