The LHC is operated by CERN, the European Organisation for Nuclear Research in Geneva, Switzerland. It is 27km in circumference, accelerates hadron particles, and collides them at the four locations where the two collider rings intersect. Hadrons are particles that consist of quarks, for example protons, neutrons and ions. The principal goal of the LHC is to improve our understanding of the universe. The standard model is the collection of scientific theories containing our current understanding of the fundamental particles and forces of the universe. This theory currently states that the two main types of elementary particles are quarks and leptons. It states there are four fundamental forces, the strong force, weak force, electromagnetic force and the gravitational force that act through the exchange of force-carrier particles. Currently the LHC runs at 13 TeV in total, so 6.5 TeV per collision beam. The energy of the collisions is key due to the equivalence of mass and energy, as made famous by Einstein’s formula E=mc2. The collisions between the beams of protons collided together by the LHC can vary due to how directly the quarks of each proton collide. This results in only a small quantity of each proton’s energy actually getting converted into particles. As the energy increases the chance of a heavier mass particle being produced in the collision become more probable. As this occurs the chance of completing part of the standard model increases.
It is unlikely that the LHC holds the key to answer all remaining questions in particle physics due to the many problems of the Standard Model of Matter. These include its inability to describe gravity on the quantum level, its reliance on arbitrary parameters such as the mass of an electron, the unknown form of dark matter and dark energy, the absence of antimatter, its lack of explanation for the early state of matter in the universe and the explanation for origin of mass. The LHC has already solved one of these key particle physics problems, the origin of mass. In 2012 the ATLAS and CMS detectors at the Large Hadron Collider observed a Higgs-Boson particle. This particle is the fundamental particle associated with the Higgs field, the field responsible for mass. In December 2015 scientists from the Atlas and CMS LHC teams both independently detected event clusters at 750GeV as bumps in their data. This was promising as to account for this bump a new particle may have been introduced, furthering The Standard Model. Unfortunately 8 months later the bump has vanished suggesting it was a statistical fluke. WIMPs are theorized weakly interacting massive particles responsible for dark matter, and the chance of detecting these increases with higher energy levels in the LHC. The LHC’s total energy capacity is 14 TeV, and it is planned to run at this energy in 2017. It is extremely unlikely that the standard model will be completed with this relatively small increase in energy, hence why the High Luminosity Large Hadron Collider (HLLHC) has been proposed.
The HL-LHC is the proposed upgrade to the LHC that will increase the total number of beam collisions by 10 times. This will result in a larger quantity of accurate measurements of newly created particles and allow for the observations of rare processes occurring “below the current sensitivity level” . This will ultimately increase our knowledge on processes happening at the high-energy frontier. The Office of High Energy Physics in the U.S. Department of energy has outlined the key science goals of particle physics for the next 20 years, all of which will be examined at the high-energy frontier. These goals are to “Use the Higgs boson as a new tool for discovery, pursue the physics associated with neutrino mass, identify the new physics of dark matter, understand cosmic acceleration: dark energy and inflation, explore the unknown: new particles, interactions, and physical principles”. Each of these goals require particle collisions at extremely high energies, hence why the LHC is the key machine to achieving them. Cern themselves understand the unlikelihood of all of these goals being achieved with the current facility, hence why they are developing a “very high energy large hadron collider” . This collider, named the Future Circular Collider (FCC) would have a 100km circumference, a collision energy of 100 TeV and be located under Lake Geneva. It will allow for the production of fundamental particles at a rate one thousand times higher and an order of magnitude more massive than the LHC. This increase in energy from 14 TeV to 100 TeV may also allow for the study of rare decays; the subatomic breakdown of particles, and a precise study of the Higgs mechanism, the method by which particles generate mass.10 The higher energy level provided by the larger size of the FCC may ultimately allow for the discovery of BSM physics (physics beyond the standard model) such as supersymmetry where particles have superpartners.
The pursuit of searching for a fundamental building block of nature is polarizing, with solid arguments both for and against the search. The key goal of particle physics is to push the boundaries of human knowledge through describing the fundamental particles and forces of our universe. It also enables us to control those fundamental building blocks of nature allowing for the development of new materials, implementations and industries. There are practical applications that stem from the search for building blocks of nature. The particle tracking technologies developed for particle accelerators are implemented in CT, MRIs and PET scans to diagnose diseases. Further technological advancements stemming from particle physics include software such as Scientific Linux, an operating system originally created for particle physics that is now utilised in many other fields of research. The key argument against high-energy particle physics is that these practical applications aren’t significant enough to justify the high costs. These costs have stalled the search before, for example with the cancelled Superconducting Super Collider (SSC) project. This collider was to be built in Texas, with a circumference of 87.1km , greatly surpassing the LHC’s. As the high energy frontier increases the expense of creating and operating such large structures can become too much for any one government to afford, and securing foreign funding is a difficult process that causes such projects as the SSC to fall apart. Perhaps the question that should be asked is not if it is worthwhile to search for a fundamental building block of nature but rather is it feasible?
Pursuing answers to the biggest scientific questions is the ultimate goal of the Large Hadron Collider. It has already solved one, the origin of mass from the Higgs Boson. It may solve further questions of particle physics, but is in inevitable that a larger and more powerful accelerator will one day replace it. Even after an upgrade to the HL-LHC and the creation of the FCC there will still be open questions in particle physics remaining. This is because “science is never finished. It proceeds by successive approximations, edging closer and closer to a complete and accurate understanding of nature, but it is never fully there.” This pursuit is the nature of science, hence why the search for fundamental building blocks of matter is ultimately worthwhile.