Editing Spin–statistics theorem (section)

== Experimental tests ==
In 1987 Greenberg and Mohapatra proposed that the spin–statistics theorem could have small violations.<ref>{{Cite journal |last1=Greenberg |first1=O. W. |last2=Mohapatra |first2=R. N. |date=1987-11-30 |title=Local Quantum Field Theory of Possible Violation of the Pauli Principle |url=https://link.aps.org/doi/10.1103/PhysRevLett.59.2507 |journal=Physical Review Letters |language=en |volume=59 |issue=22 |pages=2507–2510 |doi=10.1103/PhysRevLett.59.2507 |pmid=10035570 |issn=0031-9007|url-access=subscription }}</ref><ref>{{Cite journal |last=Hilborn |first=Robert C. |date=1995-04-01 |title=Answer to Question&nbsp;#7 ["The spin-statistics theorem", Dwight E. Neuenschwander, Am. J. Phys. 62 (11), 972 (1994)] |url=https://pubs.aip.org/ajp/article/63/4/298/1043301/Answer-to-Question-7-The-spin-statistics-theorem |journal=American Journal of Physics |language=en |volume=63 |issue=4 |pages=298–299 |doi=10.1119/1.17953 |issn=0002-9505|url-access=subscription }}</ref>
With the help of very precise calculations for states of the He atom that violate the [[Pauli exclusion principle]],<ref>{{cite journal | last = Drake | first = G. W. F. | year = 1989 | title = Predicted energy shifts for "paronic" Helium | journal = Phys. Rev. A| volume = 39 | issue = 2 
| pages = 897–899 | doi = 10.1103/PhysRevA.39.897| pmid = 9901315 | bibcode = 1989PhRvA..39..897D | s2cid = 35775478 | url = https://scholar.uwindsor.ca/physicspub/85 | url-access = subscription }}</ref> Deilamian, Gillaspy and Kelleher<ref>{{cite journal | last = Deilamian | first = K. |display-authors=etal |year = 1995 | title = Search for small violations of the symmetrization postulate in an excited state of Helium | journal = Phys. Rev. Lett. | volume = 74 | issue = 24 | pages = 4787–4790 | doi=10.1103/PhysRevLett.74.4787 | pmid = 10058599 | bibcode = 1995PhRvL..74.4787D}}</ref> looked for the 1s2s <sup>1</sup>S<sub>0</sub> state of He using an atomic-beam spectrometer. The search was unsuccessful with an upper limit of 5×10<sup>−6</sup>.