Unfinished work: Large Hadron Collider launches third run


Ten years ago, the Large Hadron Collider (LHC) at CERN brought forth the discovery of the Higgs Boson — realising the 40 year-long endeavour in search of this particle first proposed in 1964.

Ten years later, the Higgs Boson has become a central component of the Standard Model, yet still remains a contentious mystery. Like all other fundamental particles in Quantum Field Theory (QFT), the Higgs Boson is an excitation of its corresponding Higgs Field. The Higgs Field is prone to fluctuations caused by particles with which it interacts and generates mass through symmetry breaking. The Higgs Boson can be seen as a signature of this process of mass generation, like the dip in stellar luminosity during a planetary transit.

Yet for the little we know of this supposedly mass-giving, ‘god’ particle, its critically self-organised state does not seem to suggest a very stable universe for our livelihood. Borne of sci-fi existential dread, the Universe is tottering above an abyss of unknown — it is either a dynamical multiverse or a crude and unfathomable chaos that loiters and lurks beneath us. Trying to rid ourselves of this dread, scientists actively engage in the search of a beyond-the-Standard-Model (BSM) explanation — an actualisable miracle. This is the motivation behind the third, and most recent round of operations the LHC is undergoing.

This indirectly links us to the search of a new, and possibly better, candidate for dark matter

After two long hiatuses, the LHC Run 3 aims to beam upon the dark mists surrounding the Higgs Boson. It focuses on the boson’s decay into matter particles, typically of the second generation such as the charm quarks, to elucidate the boson’s mass-giving property. From then onwards, scientists can examine the match, or mismatch, between obtained results and the theory of Higgs Mechanism, to reveal whether there really exists something that goes beyond our current model of physics.

To achieve this, CERN is inputting a staggering amount — 13.6 trillion electron volts — of energy into collisions, so that more highly accelerated materials can produce heavier and, hopefully, new particles. The electronics and detectors are also upgraded to acquire more precise data. Risking damages to billion dollars super-apparatuses from dust-like, comet-speed protons, engineers are working day and night to monitor and maintain the flow of the particle-beam.

CERN also anticipates further results other than shedding light on the nature of the Higgs Boson in their most ambitious project up to date. The apparatuses are adjusted to compare electron and muon concentrations, in order to explain the matter-antimatter symmetry of our Universe. This indirectly links us to the search of a new, and possibly better, candidate for dark matter.

Similar adjustments are made on the detection modules to further probe into the ratios of leptonic decay rates. Whereas the Standard Model predicts a ratio of one — this is known as lepton flavour universality — CERN has found minor deviations from one in past LHC measurements. This third run will help collect more precise data so as to confirm whether there is a ‘signal crack’ in the Standard Model.

This will provide invaluable data on the state of matter roughly ten microseconds after the Big Bang

At last, oxygen collisions will be employed to investigate the quark-gluon plasma. This will provide invaluable data on the state of matter roughly ten microseconds after the Big Bang, which will enlighten cosmologists on the very early Planck stages of the Universe.

As ambitious as the third round already sounds, it is scheduled to be superseded by the High Luminosity (HL) upgrade, projected to increase collision yields tenfold. After another three-year shutdown, the HL-LHC will recommence operations in 2029. The quadrupole and dipole magnets accelerating particles in trajectories will be replaced and strengthened, more capable power lines will be installed, and better beam optics and collimators will be in place to allow higher-precision focus and to protect the machines from collisional damages.

With familiar physical goals, the HL-LHC will see a ground-breaking boost in the precision of collision data, which is especially important when in search of BSM physics. An additional objective is to study quantum chromodynamic (QCD) matter at high temperature and density, advancing contextual understanding of the thermodynamics of quarks.

Notwithstanding the excitement the grandeur of the LHC projects bring us, we will have to acknowledge the necessity of patience and scrupulousness when we wait and examine the results; we will also have to acknowledge the upheaving repercussions once cracks, let alone unmitigable rifts, are found in the Standard Model, as thrilling as BSM physics seem. It is for our forerunners, for us, for our future generations, to be dedicated to the LHC projects and much unfinished work waiting us ahead.

Image: CERN under License

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