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Hadrons
In particle physics, a hadron is a composite subatomic particle made of two or more quarks held together by the strong nuclear force. Pronounced , the name is derived . They are analogous to molecules, which are held together by the electric force. Most of the mass of ordinary matter comes from two hadrons: the proton and the neutron, while most of the mass of the protons and neutrons is in turn due to the binding energy of their constituent quarks, due to the strong force. Hadrons are categorized into two broad families: baryons, made of an odd number of quarks (usually three) and mesons, made of an even number of quarks (usually two: one quark and one antiquark). Protons and neutrons (which make the majority of the mass of an atom) are examples of baryons; pions are an example of a meson. A tetraquark state (an exotic meson), named the Z(4430), was discovered in 2007 by the Belle Collaboration and confirmed as a resonance in 2014 by the LHCb collaboration. Two pentaquar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exotic Hadrons
Exotic hadrons are subatomic particles composed of quarks and gluons, but which – unlike "well-known" hadrons such as protons, neutrons and mesons – consist of more than three valence quarks. By contrast, "ordinary" hadrons contain just two or three quarks. Hadrons with explicit valence gluon content would also be considered exotic. In theory, there is no limit on the number of quarks in a hadron, as long as the hadron's color charge is white, or color-neutral. Consistent with ordinary hadrons, exotic hadrons are classified as being either fermions, like ordinary baryons, or bosons, like ordinary mesons. According to this classification scheme, pentaquarks, containing five valence quarks, are exotic baryons, while tetraquarks (four valence quarks) and hexaquarks (six quarks, consisting of either a dibaryon or three quark-antiquark pairs) would be considered exotic mesons. Tetraquark and pentaquark particles are believed to have been observed and are being investigated; hexaquar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Physics
Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, 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 combinations of protons and neutrons is called nuclear physics. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) and bosons (force-carrying particles). There are three Generation (particle physics), generations of fermions, although ordinary matter is made only from the first fermion generation. The first generation consists of Up quark, up and down quarks which form protons and neutrons, and electrons and electron neutrinos. The three fundamental interactions known to be mediated by bosons are electromagnetism, the weak interaction, and the strong interaction. Quark, Quarks cannot exist on their own but form hadrons. Hadrons that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Composite Particle
This is a list of known and hypothesized microscopic particles in particle physics, condensed matter physics and cosmology. Standard Model elementary particles Elementary particles are particles with no measurable internal structure; that is, it is unknown whether they are composed of other particles. They are the fundamental objects of quantum field theory. Many families and sub-families of elementary particles exist. Elementary particles are classified according to their Spin (physics), spin. Fermions have half-integer spin while bosons have integer spin. All the elementary particles of the Standard Model have been experimentally observed, including the Higgs boson in 2012. Many other hypothetical elementary particles, such as the graviton, have been proposed, but not observed experimentally. Fermions Fermions are one of the two fundamental classes of particles, the other being bosons. Fermion particles are described by Fermi–Dirac statistics and have quantum numbers de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quark
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 nucleus, 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 (such as protons and neutrons) and mesons, or in quark–gluon plasmas. There is also the theoretical possibility of #Other_phases_of_quark_matter, more exotic phases of quark matter. For this reason, much of what is known about quarks has been drawn from observations of hadrons. Quarks have various Intrinsic and extrinsic properties, intrinsic physical property, properties, including electric charge, mass, color charge, and Spin (physics), spin. They are the only elementary particles in the Standard Mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentaquark
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. As quarks have a baryon number of , and antiquarks of , the pentaquark would have a total baryon number of 1, and thus would be a baryon. Further, because it has five quarks instead of the usual three found in regular baryons ( "triquarks"), it is classified as an exotic baryon. The name pentaquark was coined by Claude Gignoux ''et al.'' (1987) and Harry J. Lipkin in 1987; however, the possibility of five-quark particles was identified as early as 1964 when Murray Gell-Mann first postulated the existence of quarks. Although predicted for decades, pentaquarks proved surprisingly difficult to discover and some physicists were beginning to suspect that an unknown law of nature prevented their production. The first claim of pentaquark discovery was rec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exotic Baryon
In particle physics, exotic baryons are a type of hadron (bound states of quarks and gluons) with half-integer spin, but with a quark content different from the three quarks (''qqq'') present in conventional baryons. An example would be pentaquarks, consisting of four quarks and one antiquark (''qqqqq̅''). So far, the only observed exotic baryons are the pentaquarks , discovered in 2015, in 2019 and in 2022 by the LHCb collaboration. Several types of exotic baryons that require physics beyond the Standard Model have been conjectured in order to explain specific experimental anomalies. There is no independent experimental evidence for any of these particles. One example is supersymmetric R-baryons, which are bound states of 3 quarks and a gluino. The lightest R-baryon is denoted as S and consists of an up quark, a down quark, a strange quark and a gluino. This particle is expected to be long lived or stable and has been invoked to explain ultra-high-energy cosmic rays. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meson
In particle physics, a meson () is a type of hadronic subatomic particle composed of an equal number of quarks and antiquarks, usually one of each, bound together by the strong interaction. Because mesons are composed of quark subparticles, they have a meaningful physical size, a diameter of roughly one femtometre (10 m), which is about 0.6 times the size of a proton or neutron. All mesons are unstable, with the longest-lived lasting for only a few tenths of a nanosecond. Heavier mesons decay to lighter mesons and ultimately to stable electrons, neutrinos and photons. Outside the nucleus, mesons appear in nature only as short-lived products of very high-energy collisions between particles made of quarks, such as cosmic rays (high-energy protons and neutrons) and baryonic matter. Mesons are routinely produced artificially in cyclotrons or other particle accelerators in the collisions of protons, antiprotons, or other particles. Higher-energy (more massive) mesons were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LHCb
The LHCb (Large Hadron Collider beauty) experiment is a particle physics detector collecting data at the Large Hadron Collider at CERN. LHCb specializes in the measurements of the parameters of CP violation in the interactions of b- and c-hadrons (heavy particles containing a bottom and charm quarks). 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, 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 (spokesperson 2020–2023). The experiment is located at point 8 on the LHC tunnel close to Ferney-Voltaire, France just over the border from Geneva. The (small) MoEDA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Z(4430)
Z(4430) is a mesonic resonance Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximu ... discovered by the Belle experiment. It has a mass of . The resonant nature of the peak has been confirmed by the LHCb experiment with a significance of at least 13.9 σ. The particle is charged and is thought to have a quark content of , making it a tetraquark candidate. It has the spin-parity quantum numbers J P = 1+. The particle joins the X(3872), Zc(3900) and Y(4140) as exotic hadron candidates observed by multiple experiments, although it is the first to be confirmed as a resonance. See also * XYZ particle References External links Major harvest of four-leaf clover Mesons 2014 in science Subatomic particles with spin 1 {{particle-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belle Experiment
The Belle experiment was a particle physics experiment conducted by the Belle Collaboration, an international collaboration of more than 400 physicists and engineers, at the High Energy Accelerator Research Organisation ( KEK) in Tsukuba, Ibaraki Prefecture, Japan. The experiment ran from 1999 to 2010. The Belle detector was located at the collision point of the asymmetric-energy electron–positron collider, KEKB. Belle at KEKB together with the BaBar experiment at the PEP-II accelerator at SLAC were known as the B-factories as they collided electrons with positrons at the center-of-momentum energy equal to the mass of the (4S) resonance which decays to pairs of B mesons. The Belle detector was a hermetic multilayer particle detector with large solid angle coverage, vertex location with precision on the order of tens of micrometres (provided by a silicon vertex detector), good distinction between pions and kaons in the momenta range from 100 MeV/c to few GeV/c (provi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exotic Meson
In particle physics, exotic mesons are mesons that have quantum numbers not possible in the quark model; some proposals for non-standard quark model mesons could be: ;glueballs or gluonium: Glueballs have no valence quarks at all. ;tetraquarks: Tetraquarks have two valence quark–antiquark pairs. ;hybrid mesons: Hybrid mesons contain a valence quark–antiquark pair and one or more gluons. All exotic mesons are classed as mesons because they are hadrons and carry zero baryon number. Of these, glueballs must be flavor singlets – that is, must have zero isospin, strangeness, charm, bottomness, and topness. Like all particle states, exotic mesons are specified by the quantum numbers which label representations of the Poincaré symmetry, q.e., by the mass (enclosed in parentheses), and by , where is the angular momentum, is the intrinsic parity, and is the charge conjugation parity; One also often specifies the isospin of the meson. Typically, every quark model meson c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
