CERN’s Latest LHC Run: Hunting for Dark Matter Particles in 2025

Explore CERN's 2025 LHC Run 3, hunting dark matter with record 13.6 TeV collisions and AI-driven analysis.

July 28, 2025
9 min read

Introduction: Chasing the Invisible Universe

Imagine a cosmic puzzle where 27% of the pieces are invisible, yet they hold the entire picture together. That’s dark matter—a mysterious substance that doesn’t emit, absorb, or reflect light, yet exerts a gravitational pull that shapes galaxies and the universe itself. For decades, scientists have chased this elusive quarry, and in 2025, the Large Hadron Collider (LHC) at CERN is once again at the forefront of this hunt. With its latest run—Run 3, now in its fourth year—the LHC is smashing protons at record energies, sifting through the debris for clues about dark matter particles. But what makes this run so special? And could 2025 finally be the year we unmask dark matter?

In this deep dive, we’ll explore CERN’s latest efforts, unpack the science behind the search, and reveal why this year’s LHC run is a pivotal moment in our quest to understand the universe. Buckle up for a journey into the subatomic world, where cutting-edge technology meets cosmic curiosity.

The LHC: A Cosmic Time Machine

The Large Hadron Collider, nestled 100 meters underground near Geneva, Switzerland, is the world’s largest and most powerful particle accelerator. Spanning a 27-kilometer ring, it’s a marvel of engineering, using 1,232 dipole magnets and 392 quadrupole magnets to steer and focus proton beams traveling at nearly the speed of light. Since its first collisions in 2010, the LHC has been a game-changer, most notably confirming the Higgs boson in 2012—a discovery that explained how particles acquire mass. But the Higgs was just the beginning.

In 2025, the LHC is in the fourth year of Run 3, which began in 2022 after a three-year upgrade hiatus. This run is pushing the collider to new heights, with proton collisions at 13.6 teraelectronvolts (TeV)—a record energy level—and higher luminosity, meaning more particle collisions per second. According to CERN, this year’s campaign aims to deliver nearly as much data as 2024’s, despite a shorter proton-proton run, with a lead ion campaign in October and a groundbreaking oxygen ion run in July. More collisions mean more chances to spot rare particles, like those that might make up dark matter.

“The more luminosity, the more collisions for the experiments and therefore more data.” — CERN, 2025

Why does this matter? Because dark matter, which outweighs visible matter six to one, could be hiding in the subatomic shrapnel of these collisions. Let’s dive into what dark matter is and why it’s so hard to find.

Dark Matter: The Universe’s Silent Architect

Picture the universe as a grand orchestra. Visible matter—stars, planets, you, and me—is the melody, but dark matter is the conductor, silently shaping the rhythm without ever being seen. Scientists estimate dark matter accounts for 27% of the universe’s mass-energy, compared to just 5% for ordinary matter. Its gravitational influence holds galaxies together, yet it doesn’t interact with light or the electromagnetic force, making it maddeningly difficult to detect.

One leading hypothesis is that dark matter consists of weakly interacting massive particles (WIMPs). These hypothetical particles are thought to be heavy, stable, and only interact via gravity and possibly the weak nuclear force. Another contender is the “dark photon,” a long-lived particle that could mediate interactions between dark matter and ordinary matter. Both are prime targets for the LHC’s 2025 run.

“Dark matter seems to outweigh visible matter roughly six to one, making up about 27% of the universe.” — CERN

The challenge? Dark matter particles, if produced in LHC collisions, would pass through detectors unnoticed, leaving only indirect clues like “missing transverse momentum”—a gap in the energy balance of collision debris. It’s like tracking a ghost by the breeze it leaves behind.

Run 3 in 2025: What’s New?

The 2025 LHC run is a high-stakes chapter in the dark matter saga. Here’s what’s new this year:

Record Energy and Luminosity: Operating at 13.6 TeV, the LHC is colliding protons with unprecedented intensity. Higher luminosity means more collisions, increasing the odds of spotting rare events. CERN aims to deliver 280 inverse femtobarns of data in Run 3, a massive leap from the 12 inverse femtobarns used to discover the Higgs boson.
Oxygen Ion Run: For the first time, the LHC will collide oxygen ions in July 2025, offering a new way to study particle interactions. This could reveal unexpected signatures of dark matter or other exotic particles.
Upgraded Detectors: The ATLAS, CMS, ALICE, and LHCb experiments have undergone significant upgrades during the 2024/2025 year-end technical stop (YETS). For example, LHCb’s Vertex Locator sensors are now closer to the beam, improving precision, while ALICE refurbished its cavern crane to handle more data.
AI-Powered Analysis: Artificial intelligence is revolutionizing how scientists sift through the LHC’s data deluge. Machine learning algorithms, like those used in the CMS experiment’s “trigger” system, filter out noise to pinpoint potential dark matter signals.

These advancements make 2025 a critical year, but the search for dark matter isn’t just about raw power—it’s about clever strategies.

How the LHC Hunts for Dark Matter

The LHC’s dark matter search is like fishing in a cosmic ocean, casting nets for particles that might not even bite. Here’s how scientists are tackling it:

Missing Transverse Momentum

The hallmark of dark matter in LHC collisions is missing transverse momentum. When protons collide, the resulting particles should balance out in terms of energy and momentum. If a chunk of energy is “missing,” it could indicate dark matter particles that escaped detection. For instance, ATLAS has observed events where a photon with 265 GeV of transverse momentum is balanced by 268 GeV of missing momentum—a tantalizing hint.

Supersymmetry (SUSY) Models

Supersymmetry proposes that every known particle has a heavier partner with a different quantum spin. The lightest supersymmetric particle (LSP) could be a WIMP, a prime dark matter candidate. ATLAS and CMS are searching for SUSY particles by looking for missing momentum accompanied by jets or leptons. Recent ATLAS results from Run 2 data (2015–2018) have set the strongest limits yet on SUSY WIMPs, narrowing the search space.

Dark Photons and Long-Lived Particles

The CMS experiment is hunting for dark photons, hypothetical particles that could link dark matter to the Standard Model. These long-lived particles (LLPs) might decay into muons after traveling a short distance, making them detectable. The proposed MATHUSLA detector, an upgrade to the LHC, aims to catch LLPs that current detectors miss, potentially opening new doors to dark matter.

Higgs Boson Connection

Could the Higgs boson be a portal to dark matter? ATLAS has explored whether Higgs bosons decay into invisible dark matter particles, setting tight constraints using Run 2 data. New 2025 searches are probing tri-Higgs production and off-shell Higgs processes, which could reveal dark matter interactions.

“Could the Higgs boson decay into dark matter? As dark matter does not interact directly with the ATLAS detector, physicists look for signs of ‘invisible particles’.” — ATLAS Experiment

The 2025 Breakthrough Potential

Will 2025 be the year we finally catch dark matter? The odds are tantalizing but uncertain. The LHC’s Run 3 has already produced groundbreaking results, like ATLAS’s observation of quantum entanglement in top quarks and the first evidence of vector boson scattering. Yet dark matter remains elusive. Here’s why this year is pivotal:

Data Deluge: With only 5% of the LHC’s total planned data collected so far, Run 3’s increased luminosity could tip the scales. The more collisions, the higher the chance of spotting a rare dark matter signal.
New Experiments: The FASER experiment, installed in 2021, is now collecting data on neutrinos and weakly interacting particles that could interact with dark matter. Its subdetector, FASERν, is the first to detect collider-produced neutrinos, complementing ATLAS and CMS searches.
Future Horizons: The proposed Future Circular Collider (FCC), a 91-km behemoth with energies up to 100 TeV, could probe dark matter at scales the LHC can’t reach. Its feasibility study, completed in March 2025, sets the stage for a decision by 2028.

However, skeptics like physicist Sabine Hossenfelder argue that the FCC, and even the LHC’s current efforts, may only refine Standard Model measurements without uncovering dark matter. The stakes are high, and the scientific community is divided on whether bigger colliders are the answer.

Challenges and Controversies

The hunt for dark matter isn’t without hurdles. The LHC’s detectors generate petabytes of data annually, requiring sophisticated AI to filter out noise. Even then, distinguishing a dark matter signal from background events is like finding a needle in a haystack.

Cost is another sticking point. The FCC’s estimated €16–20 billion price tag has drawn criticism, with figures like Sir David King calling it “reckless” amid global challenges like climate change. Yet proponents, like CERN Director-General Fabiola Gianotti, argue that the FCC could unlock “the fundamental laws of physics and nature.”

There’s also the risk of null results. Despite a decade of searching, the LHC has found no new particles beyond the Higgs, leading some to question whether dark matter is even particle-based. Alternative theories, like modified gravity, are gaining traction, but the LHC remains the best tool to test particle hypotheses.

What’s Next for the LHC and Dark Matter?

As Run 3 continues, the LHC’s 2025 campaign is a critical stepping stone. The oxygen ion run in July could reveal new physics, while the lead ion campaign in October will probe heavy-ion collisions for dark matter clues. Meanwhile, ATLAS and CMS are analyzing Run 3 data in real-time, with results expected at conferences like LHCP 2025.

Beyond 2025, the LHC’s High-Luminosity phase (HL-LHC), set for 2029, will boost collision rates tenfold, offering even more chances to spot dark matter. The MATHUSLA detector, if approved, could catch long-lived particles, while the FCC looms as a long-term bet on high-energy physics.

“The FCC will not only be a wonderful instrument to improve our understanding of the fundamental laws of physics and nature.” — Fabiola Gianotti, CERN Director-General

Conclusion: A Cosmic Quest Continues

The search for dark matter at the LHC is like chasing a shadow in a storm—challenging, exhilarating, and full of unknowns. In 2025, CERN’s latest run is pushing the boundaries of what’s possible, from record-breaking energies to AI-driven discoveries. While dark matter remains elusive, each collision brings us closer to unraveling the universe’s deepest secrets. Will this be the year we finally glimpse the invisible? Only time—and a few trillion proton collisions—will tell.

Stay tuned to CERN’s updates on home.cern and atlas.cern for the latest breakthroughs. The cosmic hunt is on, and the universe is watching.