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 deep inelastic scattering and photo-production modes of tt pairs at the proposed LHeC and its potential to probe the electromagnetic and weak dipole moments (MDM and EDM for ttγ) of the top quark. A framework of eight independent gauge-invariant dimension-six operators involving the top quark and the electroweak gauge bosons is used. Four of these operators modify the charged tbW coupling which can be probed through the single (anti) top production mode as reported in the literature. One generates ttγ(Z) as well as tbW couplings, while the other two do not generate tbW but only ttγ(Z). Our focus is on the MDM and EDM of the top quark for which the photo-production mode of tt can be an excellent probe. At the proposed electron energies of E e = 60 and 140 GeV the LHeC could set constraints stronger than the indirect limits from b → sγ and the potential limits of the LHC through ttγ production.

Recent measurements like the ttγ production by CDF as well as the Br(B → X s γ) and A CP (B → X s γ) are used to constrain the magnetic and electric dipole moments of the top quark. The B → X s γ measurements by themselves define an allowed parameter region that sets up stringent constraints on both dipole moments.Actually, significantly more stringent than previously reported. The measurement by CDF has a ∼ 37% error that is too large to set any competitive bounds, for which a much lower 5% error would be required at least. On the other hand, because of the LHC's higher energy (apart from its higher luminosity) the same measurement performed there could indeed further constrain the allowed parameter region given by the B → X s γ measurement.

In the context of SU (2) L × U (1) dimension six operators we study the potential of the LHeC to provide information on top quark effective interactions. We focus on single antitop production and how it is affected not only by the effective tbW coupling but also by fourfermion operators. Compared to the LHC, the LHeC provides a cleaner environment to make a precise measurement of the top quark production cross section. Therefore, this machine would give a much better assesment of V tb in the context of the SM or V L in the context of higher dimension operators. The LHeC could also give a slightly better measurement for V R . For g R the HL-LHC precise measurements of F L and F R (the W -boson helicity decay ratios of top) would yield better constraints than those obtained by the LHeC. Lepton-quark contact interactions would also be significantly better probed by the LHeC, since the only way of measuring them at the LHC would be through leptonic top decay which is hardly sensitive to these interactions.

We consider the renormalization of theories with many scalar fields. We discuss at the one-loop level some simple, non-gauge models with an arbitrary number of scalars and fermions both in mass-shell and MS schemes. In MS scheme we give a detailed qualitative analysis of the RG flow of dimensionless couplings in flavor space.Comment: 32 pages, LaTeX2e, AmsLaTeX, minor typos correcte

We study the quantization of many-body systems in two dimensions in rotating coordinate frames using a gauge invariant formulation of the dynamics. We consider reference frames defined by linear and quadratic gauge conditions. In both cases we discuss their Gribov ambiguities and commutator algebra. We construct the momentum operators, inner-product and Hamiltonian in both types of gauges, for systems with and without translation invariance. The analogy with the quantization of QED in noncovariant gauges is emphasized. Our results are applied to quasi-rigid systems in the Eckart

We study the renormalization of normal mixing matrices, which includes hermitian and unitary matrices as particular cases. We give a minimal, multiplicative parametrization of counterterms, and compute the renormalized Lagrangian to one-loop order in several simple models with N species of fermions, both in on-shell and MS schemes. In on-shell scheme the mass-degenerate case is considered separately.

Single top quark production at the ILC can be used to obtain a high precision measurements of the the Vtb CKM matrix element as well as the effective tbW coupling. We have calculated the QCD correction for the cross section in the context of an effective vector boson approximation. Our results show a 10% increase due to the strong interaction.Comment: 8 pages, 4 figure