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 s ...

, majorons (named after

Ettore Majorana Ettore Majorana ( ,, uploaded 19 April 2013, retrieved 14 December 2019 ; 5 August 1906 – disappeared 25 March 1938) was an Italian theoretical physicist who worked on neutrino masses. Majorana was a supporter of Italian Fascism and a member of ...

) are a hypothetical type of

Goldstone boson In physics, Goldstone bosons or Nambu–Goldstone bosons (NGBs) are bosons that appear necessarily in models exhibiting spontaneous breakdown of continuous symmetries. They were discovered by Yoichiro Nambu within the context of the BCS superco ...

that are conjectured to mediate the

neutrino A neutrino ( ; denoted by the Greek letter ) is an elementary particle that interacts via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small ('' -ino'') that i ...

mass Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...

violation of

lepton In particle physics, a lepton is an elementary particle of half-integer spin (Spin (physics), spin ) that does not undergo strong interactions. Two main classes of leptons exist: electric charge, charged leptons (also known as the electron-li ...

number or ''B'' − ''L'' in certain high energy collisions such as : + → + + Where two

electrons The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

collide to form two W bosons and the majoron J. The U(1)_B−L symmetry is assumed to be global so that the majoron is not "eaten up" by the gauge boson and spontaneously broken. Majorons were originally formulated in four

dimension In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coo ...

s by Yuichi Chikashige, Rabindra Mohapatra and Roberto Peccei to understand neutrino masses by the seesaw mechanism and are being searched for in the neutrino-less

double beta decay In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa, inside an atomic nucleus. As in single beta decay, this process allows the atom to move cl ...

process. The name majoron was suggested by Graciela Gelmini as a derivative of the last name Majorana with the suffix -on typical of particle names like electron, proton, neutron, etc. There are theoretical extensions of this idea into supersymmetric theories and theories involving extra compactified dimensions. By propagating through the extra

spatial dimension In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coord ...

s the detectable number of majoron creation events vary accordingly. Mathematically, majorons may be modeled by allowing them to propagate through a material while all other

Standard Model The Standard Model of particle physics is the Scientific theory, theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions – excluding gravity) in the unive ...

force In physics, a force is an influence that can cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitu ...

s are fixed to an

orbifold In the mathematical disciplines of topology and geometry, an orbifold (for "orbit-manifold") is a generalization of a manifold. Roughly speaking, an orbifold is a topological space that is locally a finite group quotient of a Euclidean space. D ...

point.

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Experiments studying double beta decay have set limits on decay modes that emit majorons. NEMO has observed a variety of elements.

EXO Exo (; stylized in all caps) is a South Korean-Chinese boy band based in Seoul formed by SM Entertainment in 2011 and debuted in 2012. The group consists of nine members: Xiumin, Suho, Lay Zhang, Lay, Baekhyun, Chen (singer), Chen, Chanyeol, ...

and Kamland-Zen have set half-life limits for majoron decays in

xenon Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

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See also

References

Further reading