High energy physics (HEP) is an essential component of the physical sciences, focused on the study of the nature of matter and energy, their fundamental building blocks and interactions. Since the breakthrough Rutherford’s experiment a century ago, the investigation in HEP is accomplished through high energy particle accelerators, which have been able to unravel the deep constituents of matter, explore their behavior at short distances and produce new heavy particles.
The CERN Large Hadron Collider (LHC), colliding particles at the energy frontier, is a state-of-the art research facility and it will remain in the forefront of the investigations in the realm of HEP for at least the next 20 years. LHC is the largest and most sophisticated scientific instrument ever built. Located near Geneva, it spans the border between Switzerland and France at 100 meters beneath the surface. Its main component is a 27 km long superconducting synchrotron ring, which is responsible for the acceleration of beams of protons or heavy ions. Those beams cross in four different collision areas where detectors collect and analyze the results of such collisions. The two larger experiments, ATLAS and CMS, are general-purpose detectors designed to investigate any conceivable physical phenomena related to those collisions. Two other experiments, Alice and LHCb, have specialized detectors dedicated to the study of specific phenomena, respectively heavy-ion and b-physics.
The CMS collaboration involves about 3,000 scientists and engineers, from 184 institutions of 40 countries, from Europe, Asia, the Americas and Australasia. The CMS detector is made of several layers of specialized sub-detectors to measure the different characteristics of the produced particles. The sophisticated instrumentation includes different components: a high performance muon detector; a high resolution electromagnetic calorimeter to measure the energy of electrons and photons; a central tracking system to provide accurate measurement of charged particles; and an hermetic hadronic calorimeter to estimate the jet energy. All these sub-detector systems are immerse in a superconducting solenoid that generates a magnetic field of 4 Tesla.
The main purpose of LHC is the study of the fundamental laws of Nature at very high energies. Besides the search for the elusive Higgs boson, the last missing piece of the Standard Model (SM) of Particle Physics, the LHC is able to investigate the existence of new particles and interactions.
The discovery of the Standard Model Higgs boson announced on 4 July 2012 provided an important ratification of this theory proposed in the late 1960s to describe the electroweak interaction. The Standard Model has survived an intense experimental scrutiny during the last four decades. Maybe the most remarkable results were obtained by the Large Electron-Positron collider that in the 1990s has provided compelling evidence in favor of the SM by making precise measurements of several parameters predicted by the theory. On the other hand, the theoretical researches in the area have developed a great deal of new ideas that have anxiously waited for the right facility to be tested. The LHC could finally provide this environment capable of exploring the TeV frontier.