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Quarkonium
In particle physics, quarkonium (from quark and -onium, pl. quarkonia) is a flavorless meson whose constituents are a heavy quark and its own antiquark, making it both a neutral particle and its own antiparticle. Light quarks Light quarks ( up, down, and strange) are much less massive than the heavier quarks, and so the physical states actually seen in experiments ( η, η′, and π0 mesons) are quantum mechanical mixtures of the light quark states. The much larger mass differences between the charm and bottom quarks and the lighter quarks results in states that are well defined in terms of a quark–antiquark pair of a given flavor. Heavy quarks Examples of quarkonia are the J/ψ meson (the ground state of charmonium, ) and the meson (bottomonium, ). Because of the high mass of the top quark, toponium ( θ meson) does not exist, since the top quark decays through the electroweak interaction before a bound state can form (a rare example of a weak process proceeding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectroscopic Notation
Spectroscopic notation provides a way to specify atomic ionization states, atomic orbitals, and molecular orbitals. Ionization states Spectroscopists customarily refer to the spectrum arising from a given ionization state of a given element by the element's symbol followed by a Roman numeral. The numeral I is used for spectral lines associated with the neutral element, II for those from the first ionization state, III for those from the second ionization state, and so on. For example, "He I" denotes lines of neutral helium, and "C IV" denotes lines arising from the third ionization state, C3+, of carbon. This notation is used for example to retrieve data from thNIST Atomic Spectrum Database Atomic and molecular orbitals Before atomic orbitals were understood, spectroscopists discovered various distinctive series of spectral lines in atomic spectra, which they identified by letters. These letters were later associated with the azimuthal quantum number, ''ℓ''. The lett ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Meson
The theta meson () is a hypothetical form of quarkonium (i.e. a flavour (particle physics), flavourless meson) formed by a top quark () and top antiquark (). As a parity (physics), P-odd and charge parity, C-odd state, it is analogous to the phi meson, (), J/psi meson, () and upsilon meson, () mesons. Due to the top quark's short lifetime, the theta meson is expected to not be observed in nature. See also *List of mesons References Mesons Onia Hypothetical composite particles Subatomic particles with spin 1 {{particle-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upsilon Particle
The Upsilon meson () is a quarkonium state (i.e. Flavour (particle physics), flavourless meson) formed from a bottom quark and its antiparticle. It was discovered by the E288 experiment team, headed by Leon Lederman, at Fermilab in 1977, and was the first particle containing a bottom quark to be discovered because it is the lightest that can be produced without additional massive particles. It has a mean lifetime, lifetime of and a mass about in the ground state. See also * Oops-Leon, an erroneously-claimed discovery of a similar particle at a lower mass in 1976. * The particle is the analogous state made from strange quarks. * The particle is the analogous state made from charm quarks. * List of mesons References * * * Mesons Onia Subatomic particles with spin 1 {{particle-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onium
An onium (plural: onia) is a bound state of a particle and its antiparticle. These states are usually named by adding the suffix ''-onium'' to the name of one of the constituent particles (replacing an ''-on'' suffix when present), with one exception for "muonium"; a muon–antimuon bound pair is called "true muonium" to avoid confusion with old nomenclature. Examples Positronium is an onium which consists of an electron and a positron bound together as a long-lived metastable state. Positronium has been studied since the 1950s to understand bound states in quantum field theory. A recent development called non-relativistic quantum electrodynamics (NRQED) used this system as a proving ground. Pionium, a bound state of two oppositely-charged pions, is interesting for exploring the strong interaction. This should also be true of protonium. The true analogs of positronium in the theory of strong interactions are the quarkonium states: they are mesons made of a heavy quark and antiqua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta Meson
The eta () and eta prime meson () are isosinglet mesons made of a mixture of up, down and strange quarks and their antiquarks. The charmed eta meson () and bottom eta meson () are similar forms of quarkonium; they have the same spin and parity as the (light) defined, but are made of charm quarks and bottom quarks respectively. The top quark is too heavy to form a similar meson, due to its very fast decay. General The eta was discovered in pion–nucleon collisions at the Bevatron in 1961 by A. Pevsner ''et al''. at a time when the proposal of the Eightfold Way was leading to predictions and discoveries of new particles from symmetry considerations. The difference between the mass of the and that of the is larger than the quark model can naturally explain. This “ η–η′ puzzle ” can be resolved by the 't Hooft instanton mechanism, whose realization is also known as the Witten–Veneziano mechanism. Specifically, in QCD, the higher mass of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Term Symbol
In quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ..., the term symbol is an abbreviated description of the (total) angular momentum quantum numbers in a multi-electron atom (however, even a single electron can be described by a term symbol). Each energy level of an atom with a given electron configuration is described by not only the electron configuration but also its own term symbol, as the energy level also depends on the total angular momentum including spin. The usual atomic term symbols assume angular momentum coupling#LS coupling, LS coupling (also known as Henry Norris Russell, Russell–Frederick Albert Saunders, Saunders coupling or spin-orbit coupling). The ground state term symbol is predicted by List of Hund's rules, Hund's rules. The use of the word '' ... [...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 (provided by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLEO (particle Detector)
CLEO was a general purpose particle detector at the Cornell Electron Storage Ring (CESR), and the name of the collaboration of physicists who operated the detector. The name CLEO is not an acronym; it is short for Cleopatra and was chosen to go with CESR (pronounced Caesar). CESR was a particle accelerator designed to collide electrons and positrons at a center-of-mass energy of approximately 10 GeV. The energy of the accelerator was chosen before the first three bottom quark Upsilon resonances were discovered between 9.4 GeV and 10.4 GeV in 1977. The fourth Υ resonance, the Υ(4S), was slightly above the threshold for, and therefore ideal for the study of, B meson production. CLEO was a hermetic detector that in all of its versions consisted of a tracking system inside a solenoid magnet, a calorimeter, particle identification systems, and a muon detector.CLEO I NIMCLEO II NIM The detector underwent five major upgrades over the course of its thirty-year lifetime, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Istituto Nazionale Di Fisica Nucleare
The Istituto Nazionale di Fisica Nucleare (INFN; "National Institute for Nuclear Physics") is the coordinating institution for nuclear, particle, theoretical and astroparticle physics in Italy. History INFN was founded on 8 August 1951, to further the nuclear physics research tradition initiated by Enrico Fermi in Rome, in the 1930s. The INFN collaborates with CERN, Fermilab and various other laboratories in the world. In recent years it has provided important contributions to grid computing. During the latter half of the 1950s, the INFN designed and constructed the first Italian electron accelerator—the electron synchrotron developed in Frascati. In the early 1960s, it also constructed in Frascati the first ever electron-positron collider (ADA - ''Anello Di Accumulazione''), under the scientific leadership of Bruno Touschek. In 1968, Frascati began operating ADONE (''big'' AdA), which was the first high-energy particle collider, having a beam energy of 1.5 GeV. During the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Y(4260)
The Y(4260) is an anomalous particle with an energy of 4260 MeV which does not appear to fit into the quark model. It was discovered by the BaBar experiment at Stanford University for the Department of Energy in California and later confirmed by several other experimental collaborations. It being a Charmonium state is unlikely because the Y(4260) is heavier than the threshold for production of two D mesons, yet sits, surprisingly in a dip in the production rate for pairs of D's. It is a possibility that it is a hybrid—a predicted but not-yet-seen type of particle, where a gluon is actually a permanent part of the makeup of the particle, instead of just an ephemeral messenger keeping the quarks bound together. See also * Meson * XYZ particle * X(3872) * Z(4430) * Zc(3900) The Zc(3900) is a hadron, a type of subatomic particle made of quarks, believed to be the first tetraquark that has been observed experimentally. The discovery was made in 2013 by two independent research gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BaBar Experiment
The BaBar experiment, or simply BaBar, is an international collaboration of more than 500 physicists and engineers studying the subatomic world at energies of approximately ten times the rest mass of a proton (~10 GeV). Its design was motivated by the investigation of charge-parity violation. BaBar is located at the SLAC National Accelerator Laboratory, which is operated by Stanford University for the Department of Energy in California. Physics BaBar was set up to understand the disparity between the matter and antimatter content of the universe by measuring Charge Parity violation. CP symmetry is a combination of Charge-conjugation symmetry (C symmetry) and Parity symmetry (P symmetry), each of which are conserved separately except in weak interactions. BaBar focuses on the study of CP violation in the B meson system. The name of the experiment is derived from the nomenclature for the B meson (symbol ) and its antiparticle (symbol , pronounced B bar). The experiment's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Review Letters
''Physical Review Letters'' (''PRL''), established in 1958, is a peer-reviewed, scientific journal that is published 52 times per year by the American Physical Society. As also confirmed by various measurement standards, which include the ''Journal Citation Reports'' impact factor and the journal ''h''-index proposed by Google Scholar, many physicists and other scientists consider ''Physical Review Letters'' to be one of the most prestigious journals in the field of physics. ''According to Google Scholar, PRL is the journal with the 9th journal h-index among all scientific journals'' ''PRL'' is published as a print journal, and is in electronic format, online and CD-ROM. Its focus is rapid dissemination of significant, or notable, results of fundamental research on all topics related to all fields of physics. This is accomplished by rapid publication of short reports, called "Letters". Papers are published and available electronically one article at a time. When published in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
