The Large Hadron–Electron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy-recovery technology, it collides a novel, intense electron beam with a proton or ion beam from the High-Luminosity Large Hadron Collider (HL-LHC). The accelerator and interaction region are designed for concurrent electron–proton and proton–proton operations. This report represents an update to the LHeC’s conceptual design report (CDR), published in 2012. It comprises new results on the parton structure of the proton and heavier nuclei, QCD dynamics, and electroweak and top-quark physics. It is shown how the LHeC will open a new chapter of nuclear particle physics by extending the accessible kinematic range of lepton–nucleus scattering by several orders of magnitude. Due to its enhanced luminosity and large energy and the cleanliness of the final hadronic states, the LHeC has a strong Higgs physics programme and its own discovery potential for new physics. Building on the 2012 CDR, this report contains a detailed updated design for the energy-recovery electron linac (ERL), including a new lattice, magnet and superconducting radio-frequency technology, and further components. Challenges of energy recovery are described, and the lower-energy, high-current, three-turn ERL facility, PERLE at Orsay, is presented, which uses the LHeC characteristics serving as a development facility for the design and operation of the LHeC. An updated detector design is presented corresponding to the acceptance, resolution, and calibration goals that arise from the Higgs and parton-density-function physics programmes. This paper also presents novel results for the Future Circular Collider in electron–hadron (FCC-eh) mode, which utilises the same ERL technology to further extend the reach of DIS to even higher centre-of-mass energies.

We study the anomalous trilinear gauge couplings of Z and γ using a complete set of polarization asymmetries for the Z boson in e + e − → Z Z/Z γ processes with unpolarized initial beams. We use these polarization asymmetries, along with the cross section, to obtain a simultaneous limit on all the anomalous couplings using the Markov Chain Monte Carlo (MCMC) method. For an e + e − collider running at 500 GeV center-of-mass energy and 100 fb −1 of integrated luminosity the simultaneous limits on the anomalous couplings are 1-3×10 −3 .

The anomalous trilinear gauge couplings of Z and γ are studied in e + e − → Z Z/Z γ with longitudinal beam polarizations using a complete set of polarization asymmetries for the Z boson. We quantify the goodness of the beam polarization in terms of the likelihood and find the best choice of e − and e + polarizations to be (+0.16, −0.16), (+0.09, −0.10) and (+0.12, −0.12) for Z Z, Z γ and combined processes, respectively. Simultaneous limits on anomalous couplings are obtained for these choices of beam polarizations using Markov-Chain-Monte-Carlo (MCMC) for an e + e − collider running at √ s = 500 GeV and L = 100 fb −1 . We find the simultaneous limits for these beam polarizations to be comparable with each other and also comparable with the unpolarized beam case.

We study anomalous couplings among neutral gauge bosons in ZZ production at the LHC for √ s = 13 TeV in 4-lepton final state. We use the cross section and polarization asymmetries of the Z boson to estimate simultaneous limits on anomalous coupling using markov-chain-monte-carlo (MCMC) method for luminosities 35.9 fb −1 , 150 fb −1 , 300 fb −1 and 1000 fb −1 . The CP -even polarization asymmetry A x 2 −y 2 is sensitive mainly to the CP -odd couplings f Z/γ 4 (quadratically) providing a probe to identify CP -odd nature of interaction at the LHC. We find that the polarization asymmetries significantly improve the estimation of anomalous couplings should a deviation from the SM be observed. * rr13rs033@iiserkol.ac.in † ritesh.singh@iiserkol.ac.in arXiv:1810.11657v2 [hep-ph] 20 May 2019 * The choice of polarization vector is used to be Z (λ = ±1) = 1 √ 2 {0, ∓1, −i, 0}. † These properties has been used in Ref. [66,67].

A study of the top quark Flavour Changing Neutral Current (FCNC) through Z-boson has been performed in the proposed future e − p collider for the energy, E e(p) = 60 (7000) GeV. We considered an effective theory where the anomalous FCNC couplings are of vector and tensor nature. The effect of these couplings is probed in the single top production along with the scattered electron. The polar angle θ of the electrons coming out of the primary vertex in association with the top quark polarization asymmetries constructed from the angular distribution of the secondary lepton arising from the top decay, allow to distinguish the Lorentz structure of the coupling. From a multi-parameter analysis, we obtain a reach of O(10 −2 ) in the case of Ztu and Ztc couplings at an integrated luminosity of 2 ab −1 at 95% C.L.