Talk:Tetraneutron

Reliable?
How reliable is this stuff? ''The standard model theory suggests that four separate neutrons should result, but what was observed via their detectors was only one flash of light. The energy of this flash suggests that the four neutrons were fused together into a tetraneutron.'' From what I've seen, particle accelerator pics are a mass of lines and junk, not nice neat single flashes of light. Is this sourced from the New Scientist? William M. Connolley 21:59:15, 2005-07-09 (UTC).


 * I went through and gave this article a polish. More details on what was done, and on the work since then, including references to the recent work in this area, in what I believe is an even-handed approach. Although all of the work since the original experiment suggests it was in error.  I'm not sure if there's an agreed on citation method or format. I haven't seen consistency, but please change the formatting if there is such a format. Salsb 14:34, 10 July 2005 (UTC)

The revised article looks nice (good job digging up the references and counter-claims). Minor nitpick, though - my understanding was that it wasn't the Standard Model itself that forbade tetraneutron clusters, but that from what we know of the values for binding energies, it wouldn't be a bound system (bound system energy would be higher than four free neutrons).

Other articles that might be worth sanity checking: ...Though these all look reasonably well-researched. --Christopher Thomas 19:50, 12 July 2005 (UTC)
 * pentaquark
 * exotic meson
 * exotic baryon

I changed Standard Model to nuclear theory. The problem is indeed that known values of interaction energies indicate that multineutron clusters are unstable. So for the tetraneutron (or 3 neutrons either) to be stable there would have to be an extra term in the Hamiltonian, some sort of many-body term. The existence, or nonexistence, of such a term is the issue. Salsb 19:59, 12 July 2005 (UTC)

neutronium links
The tetraneutron, which the preponderance of evidence suggests does not exist, would result from the collision of light nuceli, and is not a decay product. So I am removing the box, and the see also's to neutronium. Salsb 20:56, 20 July 2005 (UTC)
 * as neutronium is solely neutrons, and a tetraneutron is like an atomic nuclei, it seems an appropriate link (there being a section on elemental neutronium as opposed to a phase of matter) 132.205.45.110 02:56, 21 August 2005 (UTC)

Isotope Box
None of the references to tetraneutron refer to it as an isotope of neutronium; rathers its a hypothetical neutron cluster not an element;so the addition of the isotope box strikes me as odd. Since its stability is disputed --preponderance of evidence suggests that it is not stable -- referring to it as a stable product in the decay chain strikes me as odd as well. Salsb 21:24, 20 July 2005 (UTC)


 * there is an isotope box at free neutron. Hypothetical tetraneutrons would seem to fall into the hypothetical neutronium element. The article makes claims of stability... 132.205.45.110 02:59, 21 August 2005 (UTC)
 * Read the article, only one of the references shows any evidence for stability, and the remaining references all claim that evidence either is or likely is in error. No one, as far as I am aware, not even the one group that claims stability, suggests that neutron clusters are part of a elemental decay chain. Salsb 12:20, August 22, 2005 (UTC)


 * Now we have another expt & ref - this time suggesting a half-life of many seconds. (Does it decay into 4n or He-3 ?) Isotope box seems fine. - Rod57 (talk) 13:23, 15 December 2021 (UTC)

Redundant quote
This quote: "does not seem possible to change modern nuclear Hamiltonians to bind a tetraneutron without destroying many other successful predictions of those Hamiltonians. This means that, should a recent experimental claim of a bound tetraneutron be confirmed, our understanding of nuclear forces will have to be significantly changed." is used twice in the article. Perhaps one should be removed? -- Lurlock 02:57, 29 April 2006 (UTC)

Element zero - Ridiculosium
The proposal that tetraneutron would be an element is totally absurd. Elements have to do with chemistry, and chemistry has to do with interactions involving electrons and positively charged nuclei.

According to the article, advocates of this "element number 0" qualify their proposal making it contingent on the tetraneutron being stable. Stability has nothing to do with it. There are plenty of elements that have no stable isotopes.

Atomic number zero means no charge on the nucleus, i.e. no protons, therefore no electrons, therefore no chemistry. If anyone wants to vandalise the periodic table by projecting it backwards to zero, there is no need to look for exotic stuff like tetraneutron, as the neutron is the perfect candidate.

Is this proposal a bit of Wikipedia original research? If it actually came from the scientific literature, was it made in jest?--Alkhowarizmi (talk) 11:57, 27 October 2008 (UTC)

Since when would this be an element? If it exists
I will removed the following:

"Confirmation of the existence of a tetraneutron would be a significant discovery because current nuclear theory suggests that these clusters should not be stable, and thus should not exist. If it does, then it has been suggested[citation needed] that the substance be considered an "element", and be placed on the Periodic Table of the Elements, with an atomic number of 0 (zero).

This is ridiculous. Half the elements in the periodic table are unstable. —Preceding unsigned comment added by Chanhee920 (talk • contribs) 17:11, 23 March 2009 (UTC)
 * Yes, but the unstable elements and the tetraneutron are on two greatly different levels of stability. Uranium is stable enough for it to still be primordial (even ununoctium lasts for 890 ms), but the tetraneutron would be so unstable that it would fall apart immediately once formed. Double sharp (talk) 14:37, 22 May 2012 (UTC)

Superconductivity - OR
It seems to me that the only way this could be stable would be for it to be a Bose-Einstein Condensate consisting of two neutron-neutron Cooper Pairs both sharing the same, lowest-energy quantum state, a kind of neutron superconductor. That would get rid of the degeneracy pressure. Otherwise, the Pauli exclusion principle would require two of the neutrons to have much higher energies; likely too high for the cluster to be stable (or bound) at all. Stonemason89 (talk) 15:53, 3 December 2009 (UTC)

Possible prediction of stability and lifetime
There has recently been a calculation that suggests this configuration might be stable for ~10-22s and would tie up with the tentative observational reports too. See this article or this preprint. George Dishman (talk) 12:14, 6 November 2016 (UTC)


 * Interesting use of "stable". Doesn't stable mean it doesn't decay at all ? But a "bound" state can have a half-life.
 * What half-life would be evidence for a bound state ? - Rod57 (talk) 13:19, 15 December 2021 (UTC)

2019 ARXIV paper
This paper https://arxiv.org/abs/1904.11512 was just published and came up in my email. I struggle to get my head around the paper - a long way out of my field.

Abstract :

In this work we investigate the possible condensation of tetraneutron resonant states in the lower density neutron rich gas regions in the interior of Neutron Stars (NSs). Using an effective field theoretical approach we characterize the system containing different hadronic species including, besides tetraneutrons, nucleons, a set of light clusters (3He, α particles, deuterium and tritium) and Δ-isobars. σ,ω and ρ mesonic fields provide the interaction. Assuming they can be thermodynamically produced in an equilibrated medium and scanning a range of coupling strengths to the mesonic fields from prescriptions based on isospin symmetry arguments, we study how their presence could significantly impact the nucleon pairing fractions and distribution of baryonic charge among species. We find that tetraneutrons may appear over a range of densities belonging to the outer NS crust carrying a sizable amount of baryonic charge and depleting the nucleon pairing fractions.

AKarley (talk) 22:49, 29 May 2019 (UTC)