Conveners: Monica D'Onofrio, Uta Klein and Christian Schwanenberger.
Indico web page for meetings: https://indico.cern.ch/category/17308/.
The General Physics Program of the Large Hadron-Electron Collider (LHeC)
The Large Hadron-Electron Collider (LHeC) is an innovative experiment proposed at CERN that aims to collide electrons with protons at a center-of-mass energy of 1.3 TeV. This experimental setup promises to open new frontiers in particle physics, offering a comprehensive and unique physics program for precision measurmeents that spans multiple areas of the Standard Model (SM) and beyond. The LHeC will provide unprecedented opportunities to explore Higgs physics, top-quark and heavy quark physics, electroweak interactions, quantum chromodynamics (QCD), as well as the parton distribution functions (PDFs). Additionally, the LHeC's heavy-ion program, involving collisions with lead or argon ions, will further enrich its scientific potential. In this working group we explore the opportunities of the general physics program of the LHeC with an emphasis on high-precision measurements and searches.
Higgs Physics
One of the most exciting aspects of the LHeC is its potential to advance our understanding of the Higgs boson. With a Higgs production cross-section of approximately 200 pb, the LHeC will allow for detailed studies of Higgs decays, particularly into bottom-antibottom and charm-anticharm quarks. These channels are challenging to measure at the LHC due to high background levels, making the LHeC's clean environment ideal for such investigations. Furthermore, the LHeC will provide precise measurements of the Higgs boson's couplings, including the HWW couplings, offering new insights into electroweak symmetry breaking and the mechanism of mass generation.
Searches for Beyond Standard Model (BSM) Physics and Exotics
Beyond its contributions to the Standard Model, the LHeC is uniquely positioned to explore phenomena beyond the Standard Model (BSM) and search for exotic particles. The clean environment of electron-proton collisions provides an excellent opportunity to investigate new physics scenarios that are challenging to study in proton-proton collisions. The LHeC will be sensitive to a range of BSM signatures, including searches for new heavy gauge bosons, leptoquarks, and potential dark sector particles such as dark photons. By probing electroweak and QCD interactions at high precision, the LHeC can also test for anomalous couplings and deviations from SM predictions, which could hint at new physics. These searches have the potential to uncover new particles or interactions, offering insights into the fundamental laws governing the universe and possibly addressing open questions such as the nature of dark matter and the hierarchy problem. The LHeC's contributions to BSM physics and exotic searches will complement those from the LHC, providing a broader and more comprehensive exploration of the particle physics landscape.
Quantum Chromodynamics (QCD) and PDFs
The LHeC will significantly advance our understanding of QCD, the theory of the strong interaction. It will provide high-precision measurements of PDFs, which describe the momentum distribution of quarks and gluons inside protons. These measurements are crucial for interpreting results from other collider experiments and for testing the limits of QCD. The LHeC's exploration of soft-QCD processes and the structure of the proton will also shed light on the dynamics of partons at low Bjorken x, where new phenomena may emerge.
Electroweak Physics
The LHeC will offer a unique platform for studying electroweak interactions with high precision. By probing both neutral and charged current processes, the LHeC will measure electroweak parameters with unprecedented accuracy. This will allow for stringent tests of the SM and the potential discovery of deviations that could indicate new physics. The LHeC's ability to explore the scale-dependence of electroweak couplings will provide further insights into the fundamental forces of nature.
Top-Quark and Heavy Quark Physics
The LHeC is poised to make significant contributions to top-quark physics. By studying single top-quark production and other processes, the LHeC will provide precise measurements of the top quark's properties and its interactions with other particles. This will enhance our understanding of the top quark's role in the SM and its potential connections to new physics. Additionally, the LHeC will explore the dynamics of other heavy quarks, such as charm and bottom quarks, providing valuable data for testing QCD and the SM.
Heavy-Ion Program
Beyond its electron-proton collisions, the LHeC's heavy-ion program will investigate electron-ion interactions, such as those involving lead or argon ions. This program will provide new insights into the structure of nuclei and the behavior of partons in a nuclear environment. The LHeC's heavy-ion collisions will complement the relativistic heavy-ion programs at the LHC and RHIC, contributing to our understanding of quark-gluon plasma and other exotic states of matter.
