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X17 Particle
The X17 particle is a hypothetical subatomic particle proposed by Attila Krasznahorkay and his colleagues to explain certain anomalous measurement results. The particle has been proposed to explain wide angles observed in the trajectory paths of particles produced during a nuclear transition of beryllium-8 atoms and in stable helium atoms. The X17 particle could be the force carrier for a postulated fifth force, possibly connected with dark matter, and has been described as a protophobic (i.e., ignoring protons) vector boson with a mass near . The NA64 experiment at CERN looks for the proposed X17 particle by striking the electron beams from the Super Proton Synchrotron on fixed target nuclei. History In 2015, Krasznahorkay and his colleagues at ATOMKI, the Hungarian Institute for Nuclear Research, posited the existence of a new, light boson with a mass of about (i.e., 34 times heavier than the electron). In an effort to find a dark photon, the team fired protons at thin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elementary Particle
In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. Particles currently thought to be elementary include electrons, the fundamental fermions ( quarks, leptons, antiquarks, and antileptons, which generally are matter particles and antimatter particles), as well as the fundamental bosons ( gauge bosons and the Higgs boson), which generally are force particles that mediate interactions among fermions. A particle containing two or more elementary particles is a composite particle. Ordinary matter is composed of atoms, once presumed to be elementary particles – ''atomos'' meaning "unable to be cut" in Greek – although the atom's existence remained controversial until about 1905, as some leading physicists regarded molecules as mathematical illusions, and matter as ultimately composed of energy. Subatomic constituents of the atom were first identified in the early 1930s; the electron and the proto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vector Boson
In particle physics, a vector boson is a boson whose spin equals one. The vector bosons that are regarded as elementary particles in the Standard Model are the gauge bosons, the force carriers of fundamental interactions: the photon of electromagnetism, the W and Z bosons of the weak interaction, and the gluons of the strong interaction. Some composite particles are vector bosons, for instance any vector meson (quark and antiquark). During the 1970s and 1980s, intermediate vector bosons (the W and Z bosons, which mediate the weak interaction) drew much attention in particle physics. A pseudovector boson is a vector boson that has even parity, whereas "regular" vector bosons have odd parity. There are no fundamental pseudovector bosons, but there are pseudovector mesons. In relation to the Higgs boson The W and Z particles interact with the Higgs boson as shown in the Feynman diagram. Explanation The name ''vector boson'' arises from quantum field theory. The component of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science Journalism
Science journalism conveys reporting about science to the public. The field typically involves interactions between scientists, journalists, and the public. Origins Modern science journalism dates back to ''Digdarshan'' (means showing the direction) that was an educational monthly magazine started publication in 1818 from Srirampore, Bengal, India. ''Digdarshan'' carried articles on different aspects of science, such as plants, steam boat, etc. It was available in Bengali, Hindi and English languages. One of the occasions an article was attributed to a "scientific correspondent" was "A Gale in the Bay of Biscay" by William Crookes which appeared in ''The Times'' on 18 January 1871, page 7. Thomas Henry Huxley (1825–1895) and John Tyndall (1820–1893) were scientists who were greatly involved in journalism and Peter Chalmers Mitchell (1864–1945) was Scientific Correspondent for ''The Times'' from 1918 to 1935.Gristock, J. (2006"J.G. Crowther, Kuhn and Systems of Mediatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preprint
In academic publishing, a preprint is a version of a scholarly or scientific paper that precedes formal peer review and publication in a peer-reviewed scholarly or scientific journal. The preprint may be available, often as a non-typeset version available free, before or after a paper is published in a journal. History Since 1991, preprints have increasingly been distributed electronically on the Internet, rather than as paper copies. This has given rise to massive preprint databases such as arXiv and HAL (open archive) etc. to institutional repositories. The sharing of preprints goes back to at least the 1960s, when the National Institutes of Health circulated biological preprints. After six years the use of these Information Exchange Groups was stopped, partially because journals stopped accepting submissions shared via these channels. In 2017, the Medical Research Council started supporting citations of preprints in grant and fellowship applications, and Wellcome Trust star ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anomalous Magnetic Dipole Moment
In quantum electrodynamics, the anomalous magnetic moment of a particle is a contribution of effects of quantum mechanics, expressed by Feynman diagrams with loops, to the magnetic moment of that particle. (The ''magnetic moment'', also called ''magnetic dipole moment'', is a measure of the strength of a magnetic source.) The "Dirac" magnetic moment, corresponding to tree-level Feynman diagrams (which can be thought of as the classical result), can be calculated from the Dirac equation. It is usually expressed in terms of the ''g''-factor; the Dirac equation predicts g = 2. For particles such as the electron, this classical result differs from the observed value by a small fraction of a percent. The difference is the anomalous magnetic moment, denoted a and defined as a = \frac Electron The one-loop contribution to the anomalous magnetic moment—corresponding to the first and largest quantum mechanical correction—of the electron is found by calculating the vertex functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Femtometer
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Neutron
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus, and each has a mass of approximately one atomic mass unit, they are both referred to as nucleons. Their properties and interactions are described by nuclear physics. Protons and neutrons are not elementary particles; each is composed of three quarks. The chemical properties of an atom are mostly determined by the configuration of electrons that orbit the atom's heavy nucleus. The electron configuration is determined by the charge of the nucleus, which is determined by the number of protons, or atomic number. The number of neutrons is the neutron number. Neutrons do not affect the electron configuration, but the sum of atomic and neutron numbers is the mass of the nucleus. Atoms of a chemical element t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coupling (physics)
In physics, two objects are said to be coupled when they are interacting with each other. In classical mechanics, coupling is a connection between two oscillating systems, such as pendulums connected by a spring. The connection affects the oscillatory pattern of both objects. In particle physics, two particles are coupled if they are connected by one of the four fundamental forces. Wave mechanics Coupled harmonic oscillator If two waves are able to transmit energy to each other, then these waves are said to be "coupled." This normally occurs when the waves share a common component. An example of this is two pendulums connected by a spring. If the pendulums are identical, then their equations of motion are given by m\ddot = -mg\frac - k(x-y) m\ddot = -mg \frac + k(x-y) These equations represent the simple harmonic motion of the pendulum with an added coupling factor of the spring. This behavior is also seen in certain molecules (such as CO2 and H2O), wherein two of the atoms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Nucleus
The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. After the discovery of the neutron in 1932, models for a nucleus composed of protons and neutrons were quickly developed by Dmitri Ivanenko and Werner Heisenberg. An atom is composed of a positively charged nucleus, with a cloud of negatively charged electrons surrounding it, bound together by electrostatic force. Almost all of the mass of an atom is located in the nucleus, with a very small contribution from the electron cloud. Protons and neutrons are bound together to form a nucleus by the nuclear force. The diameter of the nucleus is in the range of () for hydrogen (the diameter of a single proton) to about for uranium. These dimensions are much smaller than the diameter of the atom itself (nucleus + electron cloud), by a factor of about 26,634 (uranium atomic radiu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithium-7
Naturally occurring lithium (3Li) is composed of two stable isotope ratio, stable isotopes, lithium-6 and lithium-7, with the latter being far more abundant on Earth. Both of the natural Isotope, isotopes have an unexpectedly low nuclear binding energy per nucleon ( for lithium-6 and for lithium-7) when compared with the adjacent lighter and heavier elements, helium ( for helium-4) and beryllium ( for beryllium-9). The longest-lived Radionuclide, radioisotope of lithium is lithium-8, which has a half-life of just . Lithium-9 has a half-life of , and lithium-11 has a half-life of . All of the remaining isotopes of lithium have half-lives that are shorter than 10 Nanosecond, nanoseconds. The shortest-lived known isotope of lithium is lithium-4, which decays by proton emission with a half-life of about (), although the half-life of lithium-3 is yet to be determined, and is likely to be much shorter, like helium-2 (diproton) which undergoes proton emission within s. Lithium-7 and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dark Photon
The dark photon (also hidden, heavy, para-, or secluded photon) is a hypothetical hidden sector particle, proposed as a force carrier similar to the photon of electromagnetism but potentially connected to dark matter. In a minimal scenario, this new force can be introduced by extending the gauge group of the Standard Model of Particle Physics with a new abelian U(1) gauge symmetry. The corresponding new spin-1 gauge boson (i.e., the dark photon) can then couple very weakly to electrically charged particles through kinetic mixing with the ordinary photon and could thus be detected. The dark photon can also interact with the Standard Model if some of the fermions are charged under the new abelian group. The possible charging arrangements are restricted by a number of consistency requirements such as anomaly cancellation and constraints coming from Yukawa matrices. Motivation Observations of gravitational effects that cannot be explained by visible matter alone imply the existe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boson
In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value (0,1,2 ...). Bosons form one of the two fundamental classes of subatomic particle, the other being fermions, which have odd half-integer spin (,, ...). Every observed subatomic particle is either a boson or a fermion. Bosons are named after physicist Satyendra Nath Bose. Some bosons are elementary particles and occupy a special role in particle physics unlike that of fermions, which are sometimes described as the constituents of "ordinary matter". Some elementary bosons (for example, gluons) act as force carriers, which give rise to forces between other particles, while one (the Higgs boson) gives rise to the phenomenon of mass. Other bosons, such as mesons, are composite particles made up of smaller constituents. Outside the realm of particle physics, superfluidity arises because composite bosons (bose particles), such as low temperature helium-4 atoms, follow Bose–E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
