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    Particle physics and cosmology in 2026: a crash course

    Particle physics studies the smallest building blocks of matter, described by the Standard Model, while cosmology studies the universe as a whole; ordinary matter makes up only about 5% of the universe's content.[1][2] As of October 2026 the Large Hadron Collider is shut down for its high-luminosity upgrade, CERN has chosen a 91 km collider as its preferred next machine, and hints of evolving dark energy and a persistent Hubble tension are testing the standard model of cosmology.[3][4][5][6]

    Editor reviewedUpdated Particle physics and cosmologyPhysicsScience

    Why the field matters

    Everything you can see, from stars to people, is made of a small set of particles held together by a few forces. The theory that describes them is called the Standard Model. It has explained almost every experiment since the 1970s.[1] The odd part is that this ordinary matter is only about 5% of the universe. About 27% is invisible “dark matter” and about 68% is “dark energy”, and nobody knows what either one is.[2][7]

    Particle physicists study the very small, mostly with colliders and deep underground detectors.[8][9] Cosmologists study the universe as a whole with telescopes and sky surveys.[10][11]

    The Standard Model covers the strong, weak and electromagnetic interactions of six quarks and six leptons, and its Higgs boson was discovered in 2012.[12][13][14] Its known gaps are empirical. It does not include gravity, it originally assumed massless neutrinos, and it contains no dark matter candidate.[13][15][16] It also needs extra sources of CP violation to explain why matter outlasted antimatter.[17] The cosmological counterpart, Lambda-CDM, fits the cosmic microwave background well, but two results now strain it: a preference for time-varying dark energy and a local Hubble constant that disagrees with early-universe fits.[18][5][6]

    The map of the field

    • The energy frontier: colliders. The large-hadron-collider at CERN collides protons at 13.6 TeV, the highest energy reached in a laboratory.[19] Proposed successors include the future-circular-collider and China’s CEPC.[20][21]
    • The precision frontier. Experiments such as Muon g-2 and LHCb test the Standard Model through tiny deviations.[22][23]
    • Neutrinos. Long-baseline beams such as DUNE, reactor experiments such as JUNO, and direct mass measurements such as KATRIN.[24][25][26]
    • Dark matter searches. Underground detectors such as LZ, plus “missing energy” searches at colliders.[27][28]
    • Cosmology surveys. Galaxy maps such as the DESI survey and cosmic microwave background (CMB) telescopes such as ACT and Planck.[29][18][11]
    • Gravitational waves. The ligo-virgo-kagra network has detected about 350 signals from colliding black holes and neutron stars.[30]

    Key ideas in one paragraph each

    The Higgs field. Elementary particles get their mass by interacting with a field that fills the universe. Its particle, the Higgs boson, was found in 2012.[31][14]

    Neutrino mass. Neutrinos change type as they travel, which proves they have mass, something the Standard Model originally left out. KATRIN puts the mass below 0.45 electronvolts.[15][26]

    Sigma. Physicists measure how unlikely a result is to be a statistical fluke in standard deviations, or “sigma”. The discovery bar is 5 sigma, which is why DESI’s 2.8 to 4.2 sigma hint is not yet a discovery.[5]

    Standard rulers. Baryon acoustic oscillations leave a pattern of fixed size in how galaxies are spread out. Measuring that pattern at different epochs tracks how fast the universe expanded.[32]

    Who the main players are

    • CERN, the European laboratory with 25 member states, runs the LHC and leads the FCC study. Mark Thomson became its Director-General in January 2026.[33][34]
    • Fermilab in the US hosts DUNE and ran Muon g-2. The 2023 P5 roadmap set US priorities.[24][22][35]
    • Lawrence Berkeley National Laboratory manages DESI and is a lead lab on LZ.[36][27]
    • China’s Institute of High Energy Physics proposed CEPC, and Chinese teams run JUNO.[37][25]
    • The LIGO, Virgo and KAGRA collaborations run gravitational-wave detectors in the US, Italy and Japan.[38]

    Where the frontier is in October 2026

    The LHC finished Run 3 in June 2026 and is being rebuilt into the High-Luminosity LHC. That machine is designed to deliver ten times the original design luminosity, starting in 2030.[3][39][40] In May 2026 CERN named FCC-ee its preferred next collider, but funding is unresolved and a decision is due by 2028.[4][41] In September 2026 ATLAS and CMS reported strong evidence that Z bosons from Higgs decays are quantum entangled.[42] The 2026 Nobel Prize in Physics went to Francis Halzen for IceCube’s discovery of high-energy neutrinos from deep space.[43]

    The muon g-2 anomaly has largely faded. A new theory prediction agrees with the final measurement, though theorists’ two methods still disagree with each other.[44][45] In cosmology, DESI finished its five-year map in April 2026 and expects full results in 2027.[29][46] Two new dark energy surveys started in 2026: Rubin Observatory on the ground and NASA’s Roman in space.[47][48] The Hubble tension now stands at 5 to 7 sigma by one community analysis, which leaves open whether the cause is new physics or measurement error.[6] Gravitational-wave detectors plan to resume observing in November 2026.[49] The field tracker follows these milestones.

    Questions readers ask

    What is the Standard Model?

    It is the theory of the basic building blocks of matter, six quarks and six leptons, and three of the four fundamental forces. It was developed in the early 1970s and has explained almost all experimental results since, but it leaves out gravity.[1][12][13]

    Is the Large Hadron Collider running in 2026?

    No. Its last beams circulated on 27 June 2026, and it is in Long Shutdown 3 until a gradual restart from 2028. The High-Luminosity LHC is due to start operating in 2030.[3][40]

    Has dark energy been shown to change over time?

    Not conclusively. DESI's 2025 analysis preferred evolving dark energy at 2.8 to 4.2 sigma, below the 5-sigma standard for a discovery. Results from DESI's full five-year dataset are expected in 2027.[5][46]

    Will CERN build the Future Circular Collider?

    Undecided. In May 2026 the CERN Council named FCC-ee its preferred next flagship and asked for a funding plan, with a decision due by 2028.[4][41]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      The Standard Model explains how the basic building blocks of matter interact; it was developed in the early 1970s and has explained almost all experimental results since. confirmedas of 2026-10-10

    2. [2]

      According to CERN, ordinary matter makes up about 5% of the universe's content, dark matter about 27% and dark energy about 68%. confirmedas of 2026-10-10

    3. [3]

      Proton beams circulated in the LHC for the last time before Long Shutdown 3 on 27 June 2026; the final proton-proton collisions took place on 16 May and the final lead-lead collisions on 14 June. confirmedas of 2026-07-23

    4. [4]

      On 22 May 2026 the CERN Council updated the European Strategy for Particle Physics, naming the electron-positron Future Circular Collider as the preferred next flagship project. confirmedas of 2026-05-22

    5. [5]

      On 19 March 2025 DESI released baryon acoustic oscillation results from three years of data covering about 14 to 15 million galaxies and quasars; combined with other data they preferred evolving dark energy over a cosmological constant at 2.8 to 4.2 sigma, short of the 5-sigma discovery standard. confirmedas of 2025-03-19

    6. [6]

      The H0DN local value differs by 7.1 sigma from flat Lambda-CDM fitted to Planck, SPT and ACT CMB data, and by 5.0 sigma from a combination of Big Bang nucleosynthesis and DESI BAO data. confirmedas of 2026-10-10

    7. [7]

      NASA states that scientists do not know what dark energy is; candidate explanations include vacuum energy (a cosmological constant), a varying field called quintessence, and modified gravity. confirmedas of 2026-10-10

    8. [8]

      The Large Hadron Collider is a 27-kilometre ring about 100 metres underground on the Franco-Swiss border near Geneva; it first started up on 10 September 2008. confirmedas of 2026-10-10

    9. [9]

      LZ is run by about 250 scientists and engineers from 37 institutions and sits nearly a mile underground at the Sanford Underground Research Facility in South Dakota. confirmedas of 2025-12-08

    10. [10]

      DESI is an instrument that can capture light from 5,000 galaxies at once, mounted on the Nicholas U. Mayall 4-metre Telescope at Kitt Peak National Observatory in Arizona. confirmedas of 2025-03-19

    11. [11]

      ESA's Planck satellite mapped temperature variations in the cosmic microwave background as small as a few millionths of a degree across the whole sky. confirmedas of 2026-10-10

    12. [12]

      The Standard Model's matter particles are six quarks and six leptons, each arranged in three generations; the leptons are the electron, muon, tau and their three neutrinos. confirmedas of 2026-10-10

    13. [13]

      Of the four fundamental forces (strong, weak, electromagnetic and gravitational), the Standard Model includes only the electromagnetic, strong and weak forces; gravity has proved difficult to fit into it. confirmedas of 2026-10-10

    14. [14]

      On 4 July 2012 the ATLAS and CMS collaborations at CERN announced the discovery of a new particle consistent with the Higgs boson. confirmedas of 2026-10-10

    15. [15]

      Neutrinos change flavour (electron, muon, tau) as they travel, which proves they have mass; the Standard Model originally assumed neutrinos were massless. confirmedas of 2026-10-10

    16. [16]

      Hypothesised particles from theories beyond the Standard Model, such as supersymmetric partners of known particles, are among the proposed dark matter candidates. confirmedas of 2026-10-10

    17. [17]

      CP violation is needed to explain why today's universe contains matter with essentially no leftover antimatter. confirmedas of 2025-03-25

    18. [18]

      The Atacama Cosmology Telescope's final (DR6) analysis in March 2025 found the CMB described by Lambda-CDM and, combined with Planck, CMB lensing and DESI, a Hubble constant of 68.22 ± 0.36 km/s/Mpc (68.43 ± 0.27 with DESI DR2). confirmedas of 2025-03-18

    19. [19]

      The LHC collides protons at 13.6 TeV, the highest energy reached in a laboratory. confirmedas of 2026-10-10

    20. [20]

      The FCC plan has two stages, an electron-positron collider (FCC-ee) working as a Higgs factory first, followed by a proton-proton collider (FCC-hh) at a collision energy of around 100 TeV. confirmedas of 2025-03-31

    21. [21]

      China's proposed 100 km Circular Electron-Positron Collider (CEPC), whose technical design reports were completed in October 2025, was not included in China's 15th Five-Year Plan for 2026 to 2030. confirmedas of 2026-10-10

    22. [22]

      On 3 June 2025 Fermilab's Muon g-2 experiment released its final measurement of the muon's magnetic anomaly, with a precision of 127 parts per billion, better than its 140 ppb design goal. confirmedas of 2025-06-03

    23. [23]

      In March 2025 LHCb reported the first observation of matter-antimatter (CP) violation in baryon decays, a 2.45% asymmetry in Lambda-b baryon decays with 5.2 standard deviations significance, using LHC Run 1 and 2 data. confirmedas of 2025-03-25

    24. [24]

      DUNE sends a neutrino beam from Fermilab in Illinois to a far detector 1,300 km away at the Sanford Underground Research Facility in Lead, South Dakota, with a near detector at Fermilab. confirmedas of 2026-10-10

    25. [25]

      China's JUNO, a 20-kiloton liquid-scintillator detector 52.5 km from nuclear reactors, measured two neutrino oscillation parameters 1.6 times more precisely than all previous experiments combined, using 59.1 days of data after completion in August 2025. confirmedas of 2025-11-19

    26. [26]

      In April 2025 the KATRIN experiment reported in Science that the neutrino mass is below 0.45 electronvolts (90% confidence), half the previous limit, using 259 days of data from 2019 to 2021 and more than 36 million electrons. confirmedas of 2025-04-16

    27. [27]

      In December 2025 the LZ experiment reported 417 live days of data taken from March 2023 to April 2025 with no sign of WIMP dark matter, including a first search of the 3 to 9 GeV mass range. confirmedas of 2025-12-08

    28. [28]

      Dark matter particles produced at the LHC would escape the detectors unseen, but physicists could infer them from energy and momentum missing after a collision. confirmedas of 2026-10-10

    29. [29]

      In April 2026 DESI completed its planned five-year survey ahead of schedule, having observed more than 47 million galaxies and quasars, against an original target of 34 million, plus more than 20 million stars. confirmedas of 2026-04-15

    30. [30]

      About 350 gravitational-wave signals had been detected by the end of O4, more than two-thirds of them during O4. confirmedas of 2025-11-18

    31. [31]

      Elementary particles get their mass by interacting with the Higgs field, which was proposed in 1964 and fills the universe. confirmedas of 2026-10-10

    32. [32]

      Baryon acoustic oscillations leave a pattern in the distribution of galaxies that acts as a standard ruler, whose size at different times depends on how the universe was expanding. confirmedas of 2025-03-19

    33. [33]

      As of October 2026 CERN has 25 member states, the newest being Estonia (2024) and Slovenia (2025), and 11 associate member states including India, Brazil and Ukraine. confirmedas of 2026-10-10

    34. [34]

      British particle physicist Mark Thomson took up the role of CERN Director-General in January 2026. confirmedas of 2026-10-10

    35. [35]

      The December 2023 US P5 report recommended early implementation of DUNE, a significant US in-kind contribution to an offshore Higgs factory, and supported hosting a muon collider at Fermilab. confirmedas of 2023-12-08

    36. [36]

      DESI involves more than 900 researchers from over 70 institutions and is managed by Lawrence Berkeley National Laboratory with funding from the DOE Office of Science. confirmedas of 2026-04-15

    37. [37]

      CEPC's lead scientist said the project would be resubmitted in 2030 unless the FCC is approved first, in which case China would seek to join the FCC. confirmedas of 2026-10-10

    38. [38]

      The LIGO-Virgo-KAGRA network consists of the two LIGO detectors at Hanford and Livingston in the US, Virgo near Pisa in Italy, and KAGRA at Kamioka in Japan. confirmedas of 2025-11-18

    39. [39]

      The High-Luminosity LHC is designed to increase the LHC's integrated luminosity by a factor of ten beyond its original design value. confirmedas of 2026-10-10

    40. [40]

      During Long Shutdown 3, 1.2 km of LHC magnets and components are being replaced; the accelerator complex is due to restart gradually from 2028 and the High-Luminosity LHC to begin operating in 2030. confirmedas of 2026-06-29

    41. [41]

      The CERN Council asked CERN management to develop a financially feasible funding plan for FCC-ee with member states, other countries and the EU, will receive annual progress reports from management, and will decide on the project by 2028. confirmedas of 2026-05-22

    42. [42]

      In September 2026 CERN reported that ATLAS and CMS had found strong evidence that pairs of Z bosons from Higgs boson decays are quantum entangled, the first such evidence for Z bosons, following their earlier observation of entangled top quarks. confirmedas of 2026-09-17

    43. [43]

      The 2026 Nobel Prize in Physics, announced on 6 October 2026, went to Francis Halzen of the University of Wisconsin–Madison for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin. confirmedas of 2026-10-06

    44. [44]

      The Muon g-2 Theory Initiative's 2025 Standard Model prediction differs from the experimental average by 38 plus or minus 63 (×10⁻¹¹), showing no significant tension between theory and experiment. confirmedas of 2025-05-27

    45. [45]

      The Theory Initiative's 2020 data-driven prediction and its 2025 lattice-QCD-based prediction disagree at the level of about three standard deviations, leaving open whether a sign of new physics exists. confirmedas of 2025-07-08

    46. [46]

      DESI will keep observing through 2028, expanding its map from 14,000 to about 17,000 square degrees, and its first dark energy results from the full five-year dataset are expected in 2027. confirmedas of 2026-04-15

    47. [47]

      NSF NOIRLab, which operates Rubin with SLAC, announced on June 30, 2026 that the 10-year Legacy Survey of Space and Time had officially started after a period of system optimization and an operational readiness review; Rubin Observatory's own website dates the start of the survey to July 2026. confirmedas of 2026-10-10

    48. [48]

      NASA's Nancy Grace Roman Space Telescope launched on a SpaceX Falcon Heavy from Kennedy Space Center at 7:26 a.m. EDT on August 30, 2026. confirmedas of 2026-08-30

    49. [49]

      As of September 2026 the collaborations plan a six-month observing run, IR1, beginning in early to mid-November 2026, while plans and timing for the fifth observing run (O5) are still under discussion. confirmedas of 2026-09-03

    Revision history (2)
    1. Page created.
    2. Added Z-boson entanglement evidence, the 2026 Nobel Prize for IceCube, and links to the Rubin and Roman dark energy surveys.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "Particle physics and cosmology in 2026: a crash course." ContentLora, updated Oct 10, 2026. https://contentlora.com/explain/particle-physics-cosmology

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