Landau–Yang theorem

In quantum mechanics, the Landau–Yang theorem is a selection rule for particles that decay into two on-shell photons. The theorem states that a massive particle with spin 1 cannot decay into two photons.^{[original 1]}^{[original 2]}

Assumptions

A photon here is any particle with spin 1, without mass and without internal degrees of freedom. The photon is the only known particle with these properties.

Consequences

The theorem has several consequences in particle physics. For example:

The ρ meson cannot decay into two photons, differently from the neutral pion, that almost always decays into this final state (98.8% of times).^[1]
The Z boson cannot decay into two photons.
The Higgs boson, whose decay into two photons was observed in 2012,^[2]^[3] cannot have spin 1 in models that assume the Landau–Yang theorem. Measurements taken in 2013 have since confirmed that the Higgs has spin 0.^[4]

Original references

^ Yang, Chen Ning (1950). "Selection Rules for the Dematerialization of a Particle into Two Photons". Physical Review. 77 (2): 242–245. Bibcode:1950PhRv...77..242Y. doi:10.1103/PhysRev.77.242.
^ Landau, Lev Davidovich (1948). "The moment of a 2-photon system". Dokl. Akad. Nauk SSSR. 60: 207–209.

Additional references

^ Particle Data Group. "Light Unflavored Mesons" (PDF). Retrieved 4 August 2012.
^ ATLAS collaboration (2012). "Observation of a New Particle in the Search for the Standard Model Higgs Boson with the ATLAS Detector at the LHC". Physics Letters B. 716 (1). Phys. Lett. B: 1–29. arXiv:1207.7214. Bibcode:2012PhLB..716....1A. doi:10.1016/j.physletb.2012.08.020. Retrieved 4 August 2012.
^ CMS collaboration (2012). "Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC". Physics Letters B. 716 (1). Phys. Lett. B: 30–61. arXiv:1207.7235. Bibcode:2012PhLB..716...30C. doi:10.1016/j.physletb.2012.08.021. Retrieved 4 August 2012.
^ Aad, G.; Abajyan, T.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; et al. (ATLAS Collaboration) (7 October 2013). "Evidence for the spin-0 nature of the Higgs boson using ATLAS data". Phys. Lett. B. 726 (1–3): 120–144. arXiv:1307.1432. Bibcode:2013PhLB..726..120A. doi:10.1016/j.physletb.2013.08.026. S2CID 11562016.

[1] Yang, Chen Ning (1950). "Selection Rules for the Dematerialization of a Particle into Two Photons". Physical Review. 77 (2): 242–245. Bibcode:1950PhRv...77..242Y. doi:10.1103/PhysRev.77.242.

[2] Landau, Lev Davidovich (1948). "The moment of a 2-photon system". Dokl. Akad. Nauk SSSR. 60: 207–209.

[3] Particle Data Group. "Light Unflavored Mesons" (PDF). Retrieved 4 August 2012.

[4] ATLAS collaboration (2012). "Observation of a New Particle in the Search for the Standard Model Higgs Boson with the ATLAS Detector at the LHC". Physics Letters B. 716 (1). Phys. Lett. B: 1–29. arXiv:1207.7214. Bibcode:2012PhLB..716....1A. doi:10.1016/j.physletb.2012.08.020. Retrieved 4 August 2012.

[5] CMS collaboration (2012). "Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC". Physics Letters B. 716 (1). Phys. Lett. B: 30–61. arXiv:1207.7235. Bibcode:2012PhLB..716...30C. doi:10.1016/j.physletb.2012.08.021. Retrieved 4 August 2012.

[ATLAS_spin_parity-6] Aad, G.; Abajyan, T.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; et al. (ATLAS Collaboration) (7 October 2013). "Evidence for the spin-0 nature of the Higgs boson using ATLAS data". Phys. Lett. B. 726 (1–3): 120–144. arXiv:1307.1432. Bibcode:2013PhLB..726..120A. doi:10.1016/j.physletb.2013.08.026. S2CID 11562016.

[original 1]

[original 2]

[1]

[2]

[3]

[4]

Landau–Yang theorem

Hub talks

Landau–Yang theorem

Landau–Yang theorem

Landau–Yang theorem

Hub overview

Add your contribution

Inside this hub

Media Collections

Timelines

Articles

Notes collections

Notes

Days in Chronicle

Root Wikipedia Article

Landau–Yang theorem

Assumptions

Consequences

Original references

Additional references

Add your contribution

Related Hubs