The Large Hadron Collider (LHC) at CERN, operational since 2010, has fundamentally changed the landscape of physics research. A cutting-edge collision machine paired with advanced particle detectors and a global network of computational resources has propelled the study of particle physics into new territories. The most notable achievement of the LHC remains the discovery of the Higgs boson in 2012 by the ATLAS and CMS Collaborations, but a treasure trove of data has led to groundbreaking results, raising remarkable questions about the very fabric of our universe.

Run 1 and Run 2: A Brief Overview

Run 1 of the LHC (2010-2012) not only confirmed the existence of the Higgs boson but also detailed its critical properties. However, it was during Run 2 (2015-2018)—which produced seven times more data at increased energy levels of 13 TeV—where researchers made unprecedented strides in understanding the Higgs boson’s interactions with matter. These interactions deepened our grasp of electroweak symmetry breaking, the complex processes responsible for mass generation, and the puzzling flavour problem that describes why certain particles exhibit greater mass than others.

Significant Discoveries from Run 2

One of the most striking revelations from Run 2 was the quality and precision of measurements. ATLAS recorded an astounding 415 papers based on its Run 2 dataset—and many more are expected. Phenomena once considered rare, such as the simultaneous production of three W bosons, were observed, expanding our knowledge of vector boson scattering in ways previously unimagined.

Furthermore, ATLAS achieved significant milestones in top-quark physics by documenting the production of nearly 300 million top quarks. This large sample not only allowed for in-depth analyses but also facilitated the stunning observation of four-top-quark production—an event four thousand times rarer than the Higgs boson itself. This leap in research marked a pivotal moment for quantum information studies at high-energy physics.

Pioneering Measurements in Higgs Physics

During this run, ATLAS became a pioneering force in measuring the Higgs boson’s decay into bottom quark pairs—a phenomenon that accounts for over half of all Higgs decays—signifying a milestone in Higgs physics. Additionally, the collaboration made precise measurements of the Higgs boson's production modes and couplings, confirming various aspects of the Brout-Englert-Higgs mechanism, a fundamental theory underpinning particle physics.

Advancements in Data Analysis

While the LHC primarily seeks new particles and phenomena, it has also garnered significant results through precision measurements of known particles. The dominance of machine learning techniques in data analysis has revolutionized our understanding. For example, the collaboration leveraged cutting-edge analysis methods to refine measurements of the W boson mass and even its width, both crucial parameters in the Standard Model.

Exploration of Quark-Gluon Plasma

Run 2 also explored heavy-ion collisions that lead to the creation of quark-gluon plasma, a state of matter theorized to exist just moments after the Big Bang. This research provided insight into how matter behaves under extreme conditions, paving the way for sophisticated studies of fundamental interactions.

Looking Ahead: Future Prospects

Despite the success of its discoveries, the quest for physics beyond the Standard Model continues. ATLAS has participated in extensive searches for super-symmetry and other new physics phenomena, excluding many potential sceneries for new particles and forces while inspiring new avenues of research.

As CERN prepares for the High-Luminosity LHC—promising even more fascinating discoveries—the results from Run 2 of ATLAS stand as a testament to the power of collaboration, innovation, and inquiry. If you're excited about what could be lurking in the depths of particle physics and the secrets of the universe, stay tuned for more extraordinary revelations to come!