In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. The Standard Model presently recognizes seventeen distinct particles—twelve fermions and five bosons. As a consequence of flavor and color combinations and antimatter, the fermions and bosons are known to have 48 and 13 variations, respectively. Among the 61 elementary particles embraced by the Standard Model number: electrons and other leptons, quarks, and the fundamental bosons. Subatomic particles such as protons or neutrons, which contain two or more elementary particles, are known as composite particles.
Particle physics or high-energy physics is the study of fundamental particles and forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and neutrons, while the study of combination of protons and neutrons is called nuclear physics.
A quark is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly observable matter is composed of up quarks, down quarks and electrons. Owing to a phenomenon known as color confinement, quarks are never found in isolation; they can be found only within hadrons, which include baryons and mesons, or in quark–gluon plasmas. For this reason, much of what is known about quarks has been drawn from observations of hadrons.
Omega baryons are a family of subatomic hadrons which are represented by the symbol
Ω
and are either charge neutral or have a +2, +1 or −1 elementary charge. Additionally, they contain no up or down quarks. Omega baryons containing top quarks are also not expected to be observed. This is because the Standard Model predicts the mean lifetime of top quarks to be roughly 5×10−25 s, which is about a twentieth of the timescale necessary for the strong interactions required for Hadronization, the process by which hadrons form from quarks and gluons.
The charm quark, charmed quark, or c quark is an elementary particle found in composite subatomic particles called hadrons such as the J/psi meson and the charmed baryons created in particle accelerator collisions. Several bosons, including the W and Z bosons and the Higgs boson, can decay into charm quarks. All charm quarks carry charm, a quantum number. This second-generation particle is the third-most-massive quark, with a mass of 1.27±0.02 GeV/c2 as measured in 2022, and a charge of +2/3 e.
A pentaquark is a human-made subatomic particle, consisting of four quarks and one antiquark bound together; they are not known to occur naturally, or exist outside of experiments specifically carried out to create them.
Martinus Justinus Godefriedus "Tini" Veltman was a Dutch theoretical physicist. He shared the 1999 Nobel Prize in Physics with his former PhD student Gerardus 't Hooft for their work on particle theory.
The
J/ψ
(J/psi) meson is a subatomic particle, a flavor-neutral meson consisting of a charm quark and a charm antiquark. Mesons formed by a bound state of a charm quark and a charm anti-quark are generally known as "charmonium" or psions. The
J/ψ
is the most common form of charmonium, due to its spin of 1 and its low rest mass. The
J/ψ
has a rest mass of 3.0969 GeV/c2, just above that of the
η
c, and a mean lifetime of 7.2×10−21 s. This lifetime was about a thousand times longer than expected.
The LHCb experiment is a particle physics detector experiment collecting data at the Large Hadron Collider at CERN. LHCb is a specialized b-physics experiment, designed primarily to measure the parameters of CP violation in the interactions of b-hadrons. Such studies can help to explain the matter-antimatter asymmetry of the Universe. The detector is also able to perform measurements of production cross sections, exotic hadron spectroscopy, charm physics and electroweak physics in the forward region. The LHCb collaborators, who built, operate and analyse data from the experiment, are composed of approximately 1650 people from 98 scientific institutes, representing 22 countries. Vincenzo Vagnoni succeeded on July 1, 2023 as spokesperson for the collaboration from Chris Parkes. The experiment is located at point 8 on the LHC tunnel close to Ferney-Voltaire, France just over the border from Geneva. The (small) MoEDAL experiment shares the same cavern.
In quantum field theory, penguin diagrams are a class of Feynman diagrams which are important for understanding CP violating processes in the standard model. They refer to one-loop processes in which a quark temporarily changes flavor, and the flavor-changed quark engages in some tree interaction, typically a strong one. For the interactions where some quark flavors have much higher interaction amplitudes than others, such as CP-violating or Higgs interactions, these penguin processes may have amplitudes comparable to or even greater than those of the direct tree processes. A similar diagram can be drawn for leptonic decays.
Jonathan Richard "John" Ellis is a British-Swiss theoretical physicist.
Helen Rhoda Arnold Quinn is an Australian-born particle physicist and educator who has made major contributions to both fields. Her contributions to theoretical physics include the Peccei–Quinn theory which implies a corresponding symmetry of nature(related to matter-antimatter symmetry and the possible source of the dark matter that pervades the universe) and contributions to the search for a unified theory for the three types of particle interactions. As Chair of the Board on Science Education of the National Academy of Sciences, Quinn led the effort that produced A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas—the basis for the Next Generation Science Standards adopted by many states. Her honours include the Dirac Medal of the International Center for Theoretical Physics, the Oskar Klein Medal from the Royal Swedish Academy of Sciences, appointment as an Honorary Officer of the Order of Australia, the J. J. Sakurai Prize for Theoretical Particle Physics from the American Physical Society, the Karl Taylor Compton Medal for Leadership in Physics from the American Institute of Physics, the 2018 Benjamin Franklin Medal in Physics from the Franklin Institute, and the 2023 Harvey Prize from Technion -- Israel Institute of Technology.
Gerson Goldhaber was a German-born American particle physicist and astrophysicist. He was one of the discoverers of the J/ψ meson, which is the bound state of a charm quark and a charm anti-quark. Together with François Pierre, he led the analysis that first revealed actual charmed mesons. He worked at Lawrence Berkeley National Laboratory with the Supernova Cosmology Project, and was a professor of physics at the University of California, Berkeley as well as a professor at Berkeley's graduate school in astrophysics.
Luciano Maiani is a Sammarinese physicist. He is best known for his prediction of the charm quark with Sheldon Glashow and John Iliopoulos.
John (Jean) Iliopoulos is a Greek physicist. He is the first person to present the Standard Model of particle physics in a single report. He is best known for his prediction of the charm quark with Sheldon Glashow and Luciano Maiani. Iliopoulos is also known for demonstrating the cancellation of anomalies in the Standard model. He is further known for the Fayet–Iliopoulos D-term formula, which was introduced in 1974. He is currently an honorary member of Laboratory of theoretical physics of École normale supérieure, Paris.
Richard Keith Ellis, is a British theoretical physicist, working at the University of Durham, and a leading authority on perturbative quantum chromodynamics and collider phenomenology.
Kurt Gottfried was an Austrian-born American physicist who was professor emeritus of physics at Cornell University. He was known for his work in the areas of quantum mechanics and particle physics and was also a co-founder with Henry Way Kendall of the Union of Concerned Scientists. He wrote extensively in the areas of physics and arms control.
The D mesons are the lightest particle containing charm quarks. They are often studied to gain knowledge on the weak interaction. The strange D mesons (Ds) were called "F mesons" prior to 1986.
Sau Lan Wu is a Chinese-American particle physicist and the Enrico Fermi Distinguished Professor of Physics at the University of Wisconsin-Madison. She made important contributions towards the discovery of the J/psi particle, which provided experimental evidence for the existence of the charm quark, and the gluon, the vector boson of the strong force in the Standard Model of physics. Recently, her team located at the European Organization for Nuclear Research (CERN), using data collected at the Large Hadron Collider (LHC), was part of the international effort in the discovery of a boson consistent with the Higgs boson.
Vera G. Lüth is an experimental particle physicist and professor emerita at Stanford Linear Accelerator Center (SLAC), Stanford University, in the United States. A senator of the Helmholtz Association, she has worked in particle physics at SLAC since 1974. She is a fellow of the American Physical Society.
“One woman’s journey in physics”, Mary K Gaillard, June 1, 2016, CERN.