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Particle physics (also known as high energy physics) is a branch of physics that studies the nature of the particles that constitute matter and radiation. Although the word particle can refer to various types of very small objects (e.g. protons, gas particles, or even household dust), particle physics usually investigates the irreducibly smallest detectable particles and the fundamental interactions necessary to explain their behaviour.

In current understanding, these elementary particles are excitations of the quantum fields that also govern their interactions. The currently dominant theory explaining these fundamental particles and fields, along with their dynamics, is called the Standard Model. Thus, modern particle physics generally investigates the Standard Model and its various possible extensions, e.g. to the newest "known" particle, the Higgs boson, or even to the oldest known force field, gravity.

Subatomic particles

Modern particle physics research is focused on subatomic particles, including atomic constituents, such as electrons, protons, and neutrons (protons and neutrons are composite particles called baryons, made of quarks), that are produced by radioactive and scattering processes; such particles are photons, neutrinos, and muons, as well as a wide range of exotic particles.

Dynamics of particles are also governed by quantum mechanics; they exhibit wave–particle duality, displaying particle-like behaviour under certain experimental conditions and wave-like behaviour in others. In more technical terms, they are described by quantum state vectors in a Hilbert space, which is also treated in quantum field theory. Following the convention of particle physicists, the term elementary particles is applied to those particles that are, according to current understanding, presumed to be indivisible and not composed of other particles.

All particles and their interactions observed to date can be described almost entirely by a quantum field theory called the Standard Model. The Standard Model, as currently formulated, has 61 elementary particles. Those elementary particles can combine to form composite particles, accounting for the hundreds of other species of particles that have been discovered since the 1960s.

The Standard Model has been found to agree with almost all the experimental tests conducted to date. However, most particle physicists believe that it is an incomplete description of nature and that a more fundamental theory awaits discovery (See Theory of Everything). In recent years, measurements of neutrino mass have provided the first experimental deviations from the Standard Model, since neutrinos are massless in the Standard Model.

History

Modern physics
${\displaystyle {\hat {H}}|\psi _{n}(t)\rangle =i\hbar {\frac {d}{dt}}|\psi _{n}(t)\rangle }$ ${\displaystyle G_{\mu \nu }+\Lambda g_{\mu \nu }={\kappa }T_{\mu \nu }}$Schrödinger and Einstein field equations
Founders Max Planck Albert Einstein Niels Bohr Max Born Erwin Schrödinger Werner Heisenberg Pascual Jordan Wolfgang Pauli Paul Dirac Ernest Rutherford Louis de Broglie Satyendra Nath Bose
Concepts Topology Space Time Energy Matter Work Randomness Information Entropy Light Particle Wave
Branches Applied Experimental Theoretical Mathematical Philosophy of physics Quantum mechanics Quantum field theory Quantum information Quantum computation Electromagnetism Weak interaction Electroweak interaction Strong interaction Atomic Particle Nuclear Atomic, molecular, and optical Condensed matter Statistical Complex systems Non-linear dynamics Biophysics Neurophysics Plasma physics Special relativity General relativity Astrophysics Cosmology Theories of gravitation Quantum gravity Theory of everything
Scientists Röntgen Witten Becquerel Lorentz Planck Curie Wien Skłodowska-Curie Sommerfeld Rutherford Soddy Onnes Einstein Wilczek Born Weyl Bohr Kramers Schrödinger de Broglie Laue Bose Compton Pauli Walton Fermi van der Waals Heisenberg Dyson Zeeman Moseley Hilbert Gödel Jordan Dirac Wigner Hawking P. W. Anderson Lemaître Thomson Poincaré Wheeler Penrose Millikan Nambu von Neumann Higgs Hahn Feynman Yang Lee Lenard Salam 't Hooft Veltman Bell Gell-Mann J. J. Thomson Raman Bragg Bardeen Shockley Chadwick Lawrence Zeilinger Goudsmit Uhlenbeck
Categories Modern physics
v t e

The idea that all matter is fundamentally composed of elementary particles dates from at least the 6th century BC. In the 19th century, John Dalton, through his work on stoichiometry, concluded that each element of nature was composed of a single, unique type of particle. The word atom, after the Greek word atomos meaning "indivisible", has since then denoted the smallest particle of a chemical element, but physicists soon discovered that atoms are not, in fact, the fundamental particles of nature, but are conglomerates of even smaller particles, such as the electron. The early 20th century explorations of nuclear physics and quantum physics led to proofs of nuclear fission in 1939 by Lise Meitner (based on experiments by Otto Hahn), and nuclear fusion by Hans Bethe in that same year; both discoveries also led to the development of nuclear weapons. Throughout the 1950s and 1960s, a bewildering variety of particles were found in collisions of particles from beams of increasingly high energy. It was referred to informally as the "particle zoo". Important discoveries such as the CP violation by James Cronin and Val Fitch brought new questions to matter-antimatter imbalance. After the formulation of the Standard Model during the 1970s, physicists clarified the origin of the particle zoo. The large number of particles was explained as combinations of a (relatively) small number of more fundamental particles and framed in the context of quantum field theories. This reclassification marked the beginning of modern particle physics.

Standard Model

The current state of the classification of all elementary particles is explained by the Standard Model, which gained widespread acceptance in the mid-1970s after experimental confirmation of the existence of quarks. It describes the strong, weak, and electromagnetic fundamental interactions, using mediating gauge bosons. The species of gauge bosons are eight gluons,
W
,
W
and
Z
bosons, and the photon. The Standard Model also contains 24 fundamental fermions (12 particles and their associated anti-particles), which are the constituents of all matter. Finally, the Standard Model also predicted the existence of a type of boson known as the Higgs boson. On 4 July 2012, physicists with the Large Hadron Collider at CERN announced they had found a new particle that behaves similarly to what is expected from the Higgs boson.

Experimental laboratories

The world's major particle physics laboratories are:

• Brookhaven National Laboratory (Long Island, United States). Its main facility is the Relativistic Heavy Ion Collider (RHIC), which collides heavy ions such as gold ions and polarized protons. It is the world's first heavy ion collider, and the world's only polarized proton collider.
• Budker Institute of Nuclear Physics (Novosibirsk, Russia). Its main projects are now the electron-positron colliders VEPP-2000, operated since 2006, and VEPP-4, started experiments in 1994. Earlier facilities include the first electron–electron beam–beam collider VEP-1, which conducted experiments from 1964 to 1968; the electron-positron colliders VEPP-2, operated from 1965 to 1974; and, its successor VEPP-2M, performed experiments from 1974 to 2000.
• CERN (European Organization for Nuclear Research) (Franco-Swiss border, near Geneva). Its main project is now the Large Hadron Collider (LHC), which had its first beam circulation on 10 September 2008, and is now the world's most energetic collider of protons. It also became the most energetic collider of heavy ions after it began colliding lead ions. Earlier facilities include the Large Electron–Positron Collider (LEP), which was stopped on 2 November 2000 and then dismantled to give way for LHC; and the Super Proton Synchrotron, which is being reused as a pre-accelerator for the LHC and for fixed-target experiments.
• DESY (Deutsches Elektronen-Synchrotron) (Hamburg, Germany). Its main facility was the Hadron Elektron Ring Anlage (HERA), which collided electrons and positrons with protons. The accelerator complex is now focused on the production of synchrotron radiation with PETRA III, FLASH and the European XFEL.
• Fermi National Accelerator Laboratory (Fermilab) (Batavia, United States). Its main facility until 2011 was the Tevatron, which collided protons and antiprotons and was the highest-energy particle collider on earth until the Large Hadron Collider surpassed it on 29 November 2009.
• Institute of High Energy Physics (IHEP) (Beijing, China). IHEP manages a number of China's major particle physics facilities, including the Beijing Electron–Positron Collider II(BEPC II), the Beijing Spectrometer (BES), the Beijing Synchrotron Radiation Facility (BSRF), the International Cosmic-Ray Observatory at Yangbajing in Tibet, the Daya Bay Reactor Neutrino Experiment, the China Spallation Neutron Source, the Hard X-ray Modulation Telescope (HXMT), and the Accelerator-driven Sub-critical System (ADS) as well as the Jiangmen Underground Neutrino Observatory (JUNO).
• KEK (Tsukuba, Japan). It is the home of a number of experiments such as the K2K experiment, a neutrino oscillation experiment and Belle II, an experiment measuring the CP violation of B mesons.
• SLAC National Accelerator Laboratory (Menlo Park, United States). Its 2-mile-long linear particle accelerator began operating in 1962 and was the basis for numerous electron and positron collision experiments until 2008. Since then the linear accelerator is being used for the Linac Coherent Light Source X-ray laser as well as advanced accelerator design research. SLAC staff continue to participate in developing and building many particle detectors around the world.

Many other particle accelerators also exist. The techniques required for modern experimental particle physics are quite varied and complex, constituting a sub-specialty nearly completely distinct from the theoretical side of the field.

Theory

Quantum field theory
Feynman diagram
History
Background Field theory Electromagnetism Weak force Strong force Quantum mechanics Special relativity General relativity Gauge theory Yang–Mills theory
Symmetries Symmetry in quantum mechanics C-symmetry P-symmetry T-symmetry Lorentz symmetry Poincaré symmetry Gauge symmetry Explicit symmetry breaking Spontaneous symmetry breaking Noether charge Topological charge
Tools Anomaly Background field method BRST quantization Correlation function Crossing Effective action Effective field theory Expectation value Feynman diagram Lattice field theory LSZ reduction formula Partition function Path Integral Formulation Propagator Quantization Regularization Renormalization Vacuum state Wick's theorem Wightman Axioms
Equations Dirac equation Klein–Gordon equation Proca equations Wheeler–DeWitt equation Bargmann–Wigner equations Schwinger-Dyson equation Renormalization group equation
Standard Model Quantum electrodynamics Electroweak interaction Quantum chromodynamics Higgs mechanism
Incomplete theories String theory Supersymmetry Technicolor Theory of everything Quantum gravity
Scientists Adler Anderson Anselm Bargmann Becchi Belavin Bell Berezin Bethe Bjorken Bleuer Bogoliubov Brodsky Brout Buchholz Cachazo Callan Cardy Coleman Connes Dashen DeWitt Dirac Doplicher Dyson Englert Faddeev Fadin Fayet Fermi Feynman Fierz Fock Frampton Fritzsch Fröhlich Fredenhagen Furry Glashow Gell-Mann Glimm Goldstone Gribov Gross Gupta Guralnik Haag Hagen Han Heisenberg Hepp Higgs 't Hooft Iliopoulos Ivanenko Jackiw Jaffe Jona-Lasinio Jordan Jost Källén Kendall Kinoshita Kim Klebanov Kontsevich Kreimer Kuraev Landau Lee Lee Lehmann Leutwyler Lipatov Łopuszański Low Lüders Maiani Majorana Maldacena Matsubara Migdal Mills Møller Naimark Nambu Neveu Nishijima Oehme Oppenheimer Osborn Osterwalder Parisi Pauli Peccei Peskin Plefka Polchinski Polyakov Pomeranchuk Popov Proca Quinn Rouet Rubakov Ruelle Sakurai Salam Schrader Schwarz Schwinger Segal Seiberg Semenoff Shifman Shirkov Skyrme Sommerfield Stora Stueckelberg Sudarshan Symanzik Takahashi Thirring Tomonaga Tyutin Vainshtein Veltman Veneziano Virasoro Ward Weinberg Weisskopf Wentzel Wess Wetterich Weyl Wick Wightman Wigner Wilczek Wilson Witten Yang Yukawa Zamolodchikov Zamolodchikov Zee Zimmermann Zinn-Justin Zuber Zumino
v t e

Theoretical particle physics attempts to develop the models, theoretical framework, and mathematical tools to understand current experiments and make predictions for future experiments (see also theoretical physics). There are several major interrelated efforts being made in theoretical particle physics today.

One important branch attempts to better understand the Standard Model and its tests. Theorists make quantitative predictions of observables at collider and astronomical experiments, which along with experimental measurements is used to extract the parameters of the Standard Model with less uncertainty. This work probes the limits of the Standard Model and therefore expands scientific understanding of nature's building blocks. Those efforts are made challenging by the difficulty of calculating high precision quantities in quantum chromodynamics. Some theorists working in this area use the tools of perturbative quantum field theory and effective field theory, referring to themselves as phenomenologists. Others make use of lattice field theory and call themselves lattice theorists.

Another major effort is in model building where model builders develop ideas for what physics may lie beyond the Standard Model (at higher energies or smaller distances). This work is often motivated by the hierarchy problem and is constrained by existing experimental data. It may involve work on supersymmetry, alternatives to the Higgs mechanism, extra spatial dimensions (such as the Randall–Sundrum models), Preon theory, combinations of these, or other ideas.

A third major effort in theoretical particle physics is string theory. String theorists attempt to construct a unified description of quantum mechanics and general relativity by building a theory based on small strings, and branes rather than particles. If the theory is successful, it may be considered a "Theory of Everything", or "TOE".

There are also other areas of work in theoretical particle physics ranging from particle cosmology to loop quantum gravity.

This division of efforts in particle physics is reflected in the names of categories on the arXiv, a preprint archive: hep-th (theory), hep-ph (phenomenology), hep-ex (experiments), hep-lat (lattice gauge theory).

Practical applications

In principle, all physics (and practical applications developed therefrom) can be derived from the study of fundamental particles. In practice, even if "particle physics" is taken to mean only "high-energy atom smashers", many technologies have been developed during these pioneering investigations that later find wide uses in society. Particle accelerators are used to produce medical isotopes for research and treatment (for example, isotopes used in PET imaging), or used directly in external beam radiotherapy. The development of superconductors has been pushed forward by their use in particle physics. The World Wide Web and touchscreen technology were initially developed at CERN. Additional applications are found in medicine, national security, industry, computing, science, and workforce development, illustrating a long and growing list of beneficial practical applications with contributions from particle physics.

Future

The primary goal, which is pursued in several distinct ways, is to find and understand what physics may lie beyond the standard model. There are several powerful experimental reasons to expect new physics, including dark matter and neutrino mass. There are also theoretical hints that this new physics should be found at accessible energy scales.

Much of the effort to find this new physics are focused on new collider experiments. The Large Hadron Collider (LHC) was completed in 2008 to help continue the search for the Higgs boson, supersymmetric particles, and other new physics. An intermediate goal is the construction of the International Linear Collider (ILC), which will complement the LHC by allowing more precise measurements of the properties of newly found particles. In August 2004, a decision for the technology of the ILC was taken but the site has still to be agreed upon.

In addition, there are important non-collider experiments that also attempt to find and understand physics beyond the Standard Model. One important non-collider effort is the determination of the neutrino masses, since these masses may arise from neutrinos mixing with very heavy particles. In addition, cosmological observations provide many useful constraints on the dark matter, although it may be impossible to determine the exact nature of the dark matter without the colliders. Finally, lower bounds on the very long lifetime of the proton put constraints on Grand Unified Theories at energy scales much higher than collider experiments will be able to probe any time soon.

In May 2014, the Particle Physics Project Prioritization Panel released its report on particle physics funding priorities for the United States over the next decade. This report emphasized continued U.S. participation in the LHC and ILC, and expansion of the Deep Underground Neutrino Experiment, among other recommendations.

See also

• Particle physics and representation theory
• Atomic physics
• Astronomy
• High pressure
• International Conference on High Energy Physics
• Introduction to quantum mechanics
• List of accelerators in particle physics
• List of particles
• Magnetic monopole
• Micro black hole
• Number theory
• Resonance (particle physics)
• Self-consistency principle in high energy physics
• Non-extensive self-consistent thermodynamical theory
• Standard Model (mathematical formulation)
• Stanford Physics Information Retrieval System
• Timeline of particle physics
• Unparticle physics
• Tetraquark
• Track significance
• International Conference on Photonic, Electronic and Atomic Collisions

References

1. "The Higgs Boson". CERN.
2. "The BEH-Mechanism, Interactions with Short Range Forces and Scalar Particles" (PDF). 8 October 2013.
3. Terranova, Francesco (2021). A Modern Primer in Particle and Nuclear Physics. Oxford Univ. Press. ISBN 978-0-19-284524-5.
4. ^ Braibant, S.; Giacomelli, G.; Spurio, M. (2009). Particles and Fundamental Interactions: An Introduction to Particle Physics. Springer. pp. 313–314. ISBN 978-94-007-2463-1.
5. ^ "Particle Physics and Astrophysics Research". The Henryk Niewodniczanski Institute of Nuclear Physics. Archived from the original on 2 October 2013. Retrieved 31 May 2012.
6. "Neutrinos in the Standard Model". The T2K Collaboration. Retrieved 15 October 2019.
7. "Fundamentals of Physics and Nuclear Physics" (PDF). Archived from the original (PDF) on 2 October 2012. Retrieved 21 July 2012.
8. "Scientific Explorer: Quasiparticles". Sciexplorer.blogspot.com. 22 May 2012. Archived from the original on 19 April 2013. Retrieved 21 July 2012.
9. "Antimatter". 1 March 2021.
10. Weinberg, Steven (1995–2000). The quantum theory of fields. Cambridge: Cambridge University Press. ISBN 978-0521670531.
11. Jaeger, Gregg (2021). "The Elementary Particles of Quantum Fields". Entropy. 23 (11): 1416. Bibcode:2021Entrp..23.1416J. doi:10.3390/e23111416. PMC 8623095. PMID 34828114.
12. Nakamura, K (1 July 2010). "Review of Particle Physics". Journal of Physics G: Nuclear and Particle Physics. 37 (7A): 075021. Bibcode:2010JPhG...37g5021N. doi:10.1088/0954-3899/37/7A/075021. PMID 10020536.
13. Mann, Adam (28 March 2013). "Newly Discovered Particle Appears to Be Long-Awaited Higgs Boson". Wired Science. Retrieved 6 February 2014.
14. Harrison, M.; Ludlam, T.; Ozaki, S. (March 2003). "RHIC project overview". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 499 (2–3): 235–244. Bibcode:2003NIMPA.499..235H. doi:10.1016/S0168-9002(02)01937-X.
15. Courant, Ernest D. (December 2003). "Accelerators, Colliders, and Snakes". Annual Review of Nuclear and Particle Science. 53 (1): 1–37. Bibcode:2003ARNPS..53....1C. doi:10.1146/annurev.nucl.53.041002.110450. ISSN 0163-8998.
16. "index". Vepp2k.inp.nsk.su. Archived from the original on 29 October 2012. Retrieved 21 July 2012.
17. "The VEPP-4 accelerating-storage complex". V4.inp.nsk.su. Archived from the original on 16 July 2011. Retrieved 21 July 2012.
18. "VEPP-2M collider complex" (in Russian). Inp.nsk.su. Retrieved 21 July 2012.
19. "The Budker Institute of Nuclear Physics". English Russia. 21 January 2012. Retrieved 23 June 2012.
20. "Welcome to". Info.cern.ch. Retrieved 23 June 2012.
21. "Germany's largest accelerator centre". Deutsches Elektronen-Synchrotron DESY. Retrieved 23 June 2012.
22. "Fermilab | Home". Fnal.gov. Retrieved 23 June 2012.
23. "IHEP | Home". ihep.ac.cn. Archived from the original on 1 February 2016. Retrieved 29 November 2015.
24. "Kek | High Energy Accelerator Research Organization". Legacy.kek.jp. Archived from the original on 21 June 2012. Retrieved 23 June 2012.
25. "SLAC National Accelerator Laboratory Home Page". Retrieved 19 February 2015.
26. Wolchover, Natalie (22 December 2017). "The Best Explanation for Everything in the Universe". The Atlantic. Retrieved 11 March 2022.
27. "arXiv.org e-Print archive".
28. "Fermilab | Science at Fermilab | Benefits to Society". Fnal.gov. Retrieved 23 June 2012.

Further reading

Introductory reading

• Close, Frank (2004). Particle Physics: A Very Short Introduction. Oxford University Press. ISBN 978-0-19-280434-1.
• Close, Frank; Marten, Michael; Sutton, Christine (2004). The Particle Odyssey: A Journey to the Heart of the Matter. Bibcode:2002pojh.book.....C. ISBN 9780198609438. {{cite book}}: |journal= ignored (help)
• Ford, Kenneth W. (2005). The Quantum World. Harvard University Press.
• Oerter, Robert (2006). The Theory of Almost Everything: The Standard Model, the Unsung Triumph of Modern Physics. Plume.
• Schumm, Bruce A. (2004). Deep Down Things: The Breathtaking Beauty of Particle Physics. Johns Hopkins University Press. ISBN 978-0-8018-7971-5.
• Close, Frank (2006). The New Cosmic Onion. Taylor & Francis. ISBN 978-1-58488-798-0.

Advanced reading

• Robinson, Matthew B.; Bland, Karen R.; Cleaver, Gerald. B.; Dittmann, Jay R. (2008). "A Simple Introduction to Particle Physics". arXiv:0810.3328 .
• Robinson, Matthew B.; Ali, Tibra; Cleaver, Gerald B. (2009). "A Simple Introduction to Particle Physics Part II". arXiv:0908.1395 .
• Griffiths, David J. (1987). Introduction to Elementary Particles. Wiley, John & Sons, Inc. ISBN 978-0-471-60386-3.
• Kane, Gordon L. (1987). Modern Elementary Particle Physics. Perseus Books. ISBN 978-0-201-11749-3.
• Perkins, Donald H. (1999). Introduction to High Energy Physics. Cambridge University Press. ISBN 978-0-521-62196-0.
• Povh, Bogdan (1995). Particles and Nuclei: An Introduction to the Physical Concepts. Springer-Verlag. ISBN 978-0-387-59439-2.
• Boyarkin, Oleg (2011). Advanced Particle Physics Two-Volume Set. CRC Press. ISBN 978-1-4398-0412-4.
• Terranova, Francesco (2021). A Modern Primer in Particle and Nuclear Physics. Oxford Univ. Press. ISBN 978-0192845252.

External links

• Symmetry magazine
• Fermilab
• Particle physics – it matters – the Institute of Physics
• Nobes, Matthew (2002) "Introduction to the Standard Model of Particle Physics" on Kuro5hin: Part 1, Part 2, Part 3a, Part 3b.
• CERN – European Organization for Nuclear Research
• The Particle Adventure – educational project sponsored by the Particle Data Group of the Lawrence Berkeley National Laboratory (LBNL)

v t e Particles in physics
Elementary	Fermions Quarks Up (quark antiquark) Down (quark antiquark) Charm (quark antiquark) Strange (quark antiquark) Top (quark antiquark) Bottom (quark antiquark) Leptons Electron Positron Muon Antimuon Tau Antitau Neutrino Electron neutrino Electron antineutrino Muon neutrino Muon antineutrino Tau neutrino Tau antineutrino Bosons Gauge Photon Gluon W and Z bosons Scalar Higgs boson Ghost fields Faddeev–Popov ghosts Hypothetical Superpartners Gauginos Gluino Gravitino Photino Others Axino Chargino Higgsino Neutralino Sfermion (Stop squark) Others Axion Curvaton Dilaton Dual graviton Graviphoton Graviton Inflaton Leptoquark Magnetic monopole Majoron Majorana fermion Dark photon Preon Sterile neutrino Tachyon W′ and Z′ bosons X and Y bosons
Composite	Hadrons Baryons Nucleon Proton Antiproton Neutron Antineutron Delta baryon Lambda baryon Sigma baryon Xi baryon Omega baryon Mesons Pion Rho meson Eta and eta prime mesons Bottom eta meson Phi meson J/psi meson Omega meson Upsilon meson Kaon B meson D meson Quarkonium Exotic hadrons Tetraquark (Double-charm tetraquark) Pentaquark Others Atomic nuclei Atoms Exotic atoms Positronium Muonium Tauonium Onia Pionium Protonium Superatoms Molecules Hypothetical Baryons Hexaquark Heptaquark Skyrmion Mesons Glueball Theta meson T meson Others Mesonic molecule Pomeron Diquark R-hadron
Quasiparticles	Anyon Davydov soliton Dropleton Exciton Fracton Hole Magnon Phonon Plasmaron Plasmon Polariton Polaron Roton Trion
Lists	Baryons Mesons Particles Quasiparticles Timeline of particle discoveries
Related	History of subatomic physics timeline Standard Model mathematical formulation Subatomic particles Particles Antiparticles Nuclear physics Eightfold way Quark model Exotic matter Massless particle Relativistic particle Virtual particle Wave–particle duality Particle chauvinism
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v t e Standard Model
Background	Particle physics Fermions Gauge boson Higgs boson Quantum field theory Gauge theory Strong interaction Color charge Quantum chromodynamics Quark model Electroweak interaction Weak interaction Quantum electrodynamics Fermi's interaction Weak hypercharge Weak isospin
Constituents	CKM matrix Spontaneous symmetry breaking Higgs mechanism Mathematical formulation of the Standard Model
Beyond the Standard Model	Evidence Hierarchy problem Dark matter Cosmological constant problem Strong CP problem Neutrino oscillation Theories Technicolor Kaluza–Klein theory Grand Unified Theory Theory of everything Supersymmetry MSSM NMSSM Split supersymmetry Supergravity Quantum gravity String theory Superstring theory Loop quantum gravity Causal dynamical triangulation Canonical quantum gravity Superfluid vacuum theory Twistor theory
Experiments	Gran Sasso INO LHC SNO Super-K Tevatron
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