Majoron

In particle physics, majorons (named after Ettore Majorana) are a hypothetical type of Goldstone boson that are theorized to mediate the neutrino mass violation of lepton number or B − L in certain high energy collisions such as


e−
 + 
e−
 → 
W−
 + 
W−
 + 
J
Not to be confused with Majorana fermion.
Majoron
CompositionElementary particle
StatisticsBosonic
StatusHypothetical
SymbolJ
TheorizedY. Chikashige, R. N. Mohapatra, and R. D. Peccei
Massunknown
Electric charge0 e
Spin0[1]

Where two electrons 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 dimensions by Y. Chikashige, R. N. Mohapatra and R. D. Peccei to understand neutrino masses by the seesaw mechanism and are being searched for in the neutrino-less double beta decay process. There are theoretical extensions of this idea into supersymmetric theories and theories involving extra compactified dimensions. By propagating through the extra spatial dimensions 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 forces are fixed to an orbifold point.

Searches

Experiments studying double beta decay have set limits on decay modes that emit majorons.

NEMO[2] has observed a variety of elements. EXO[3] and Kamland-Zen[4] have set half-life limits for majoron decays in xenon.

References
  1. Lattanzi, M. (2008). "Decaying Majoron Dark Matter and Neutrino Masses". AIP Conference Proceedings. 966 (1): 163–169. arXiv:0802.3155. Bibcode:2008AIPC..966..163L. doi:10.1063/1.2836988.
  2. Arnold, R.; Augier, C.; Baker, J. D.; Barabash, A. S.; Basharina-Freshville, A.; Blondel, S.; et al. (12 June 2014). "Search for neutrinoless double-beta decay of ... with the NEMO-3 detector". Physical Review D. 89 (11): 111101. arXiv:1311.5695. Bibcode:2014PhRvD..89k1101A. doi:10.1103/PhysRevD.89.111101.
  3. Albert, J. B.; Auty, D. J.; Barbeau, P. S.; Beauchamp, E.; Beck, D.; Belov, V.; et al. (10 November 2014). "Search for Majoron-emitting modes of double-beta decay of ... with EXO-200". Physical Review D. 90 (9): 092004. arXiv:1409.6829. Bibcode:2014PhRvD..90i2004A. doi:10.1103/PhysRevD.90.092004.
  4. Gando, A.; Gando, Y.; Hanakago, H.; Ikeda, H.; Inoue, K.; Kato, R.; et al. (6 August 2012). "Limits on Majoron-emitting double- decays of ... Xe in the KamLAND-Zen experiment". Physical Review C. 86 (2): 021601. arXiv:1205.6372. Bibcode:2012PhRvC..86b1601G. doi:10.1103/PhysRevC.86.021601.

Further reading
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