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Related to Why is Anti-deuterium so important in the search for dark matter?. If the detection of anti-helium in the cosmic rays would be a signature of dark matter, is it possible to measure any light anti-nuclei in particle acceleration collisions? What would be the probability of observing these light anti-nuclei?

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    $\begingroup$ Note that the answer to the question you reference states up front that it has nothing to do with dark matter, but instead the balance of matter and anti-matter in the universe. And, yes, anti-protons, the lightest anti-nuclei, are produced in particle accelerator collisions and studied. CERN is even making anti-hydrogen in (small) quantity... $\endgroup$
    – Jon Custer
    May 7, 2018 at 16:42
  • $\begingroup$ Deuterium has a small binding energy (2.2 MeV), so it's unlikely to produce it (or anti-it) intact at any appreciable energy. $\endgroup$
    – JEB
    May 7, 2018 at 17:25
  • $\begingroup$ Hi Juanjo. Welcome to Phys.SE. I removed your last subquestion, as we prefer one subquestion per post. $\endgroup$
    – Qmechanic
    May 7, 2018 at 17:42
  • $\begingroup$ I'm pretty sure that the first production of anti-helium was reported in a Nature paper by the STAR collaboration in about 2007 --- I remember where I was when I read it because the print version of the paper had an important figure with a very confusing printing error. I'll try to construct a proper answer later. $\endgroup$
    – rob
    May 8, 2018 at 4:30

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A lot of effort in analysis of LHC data goes into trying to find supersymmetric particles , unsuccessfully at the moment. There are theoretical models for dark matter which assuming supersymmetry is what the WIMPs are about derives a signal of antideuterons from neutralino interactions, for example:

Antideuterons, ... As explained in Sect. II, they form when an antiproton and an antineutron merge together. The two antinucleons must be at rest with respect to each other in order for fusion to take place successfully.

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On the other hand, supersymmetric ̄D’s are manufactured at rest with respect to the Galaxy. In neutralino annihilations, antinucleons are predominantly produced with low energies. This feature is further enhanced by their subsequent fusion into antideuterons, hence a fairly flat spectrum for supersymmetric antideuterium nuclei as shown in Sect. IV. Below a few GeV/n, secondary antideuterons are quite suppressed with respect to their supersymmetric partners. That low–energy suppression is orders of magnitude more effective for antideuterons than for antiprotons. This makes cosmic–ray antideuterons a much better probe of s upersymmetric dark matter than antiprotons

So one has to first verify that supersymmetry is true, that neutralinos exist, and have enough of them to annihilate into antiprotons and antineutrons so that they can bind into deuterium.

As there is no experimental discovery of supesymmetry in the current accelerators, this whole scheme is highly theoretical for dark matter, and certainly cannot be explored in a particle accelerator setting, unless with very low energy beams in the way antihydrogen is generated at CERN, but this will have no connection with dark matter. (Considering the difficulties of controlling neutral beams antideuterium will be much more difficult as it needs antineutrons).

Edit after further search:

In heavy ion collisions, light nuclei have been created in Alice experiment .

The measurement by ALICE comparing the mass-to-charge ratios in deuterons/antideuterons and in helium-3/antihelium-3 confirms the fundamental symmetry known as CPT in these light nuclei.

This demonstrates the antiparticle production possibility in the quark gluon plasma, to explain antimatter creation in the early universe, not dark matter, as proposed by neutralino interactions .

So the answer is, antideuterons and antiheliums have been seen in accelerators, but their observation is related to antimatter production, not dark matter. The proposal for dark matter comes from supersymmetric theories combined with hypothesis dark matter is neutralinos.

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  • $\begingroup$ Thanks for the answer, but my question was more going in the direction of what is the reaction (maybe explained with a Feynman diagram) that produces anti-nuclei in an accelerator. In the thread Why is Anti-deuterium so important in the search for dark matter? you explained that it is possible to produce anti-helium but the probability is very low coming from pair production, what about in a collision in an accelerator? What about with anti-deuterium and heavier nuclei there? $\endgroup$
    – Juanjo
    May 8, 2018 at 3:16
  • $\begingroup$ within the standard model it is very small at the energies accessible to accelerators. One would need quark gluon plasma energies, and the combinatorics of getting the correct quarks and correct antiquarks to match up , in principle possible, would depress the probability, though as the strong interaction is involved it will not be simple feynman ( a huge multiplicity of them as gluons are self interacting) diagrams but lattice QCD or some other apprppriate theory. complicated arxiv.org/abs/1011.5612 $\endgroup$
    – anna v
    May 8, 2018 at 3:55

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