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How do we know that we measure only the higgs boson and not also its superpartner, the width of the spike is quite wide (a few GeV).

enter image description here

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  • $\begingroup$ Well, for starters, this is a plot of decays to two photons. A Higgsino can't decay to two photons. $\endgroup$ – knzhou Aug 25 '18 at 4:49
  • $\begingroup$ @knzhou what do you mean? It's taken from the Atlas link in the question? $\endgroup$ – 0x90 Aug 25 '18 at 4:53
  • $\begingroup$ It says "selected diphoton sample". That means decays to two photons. $\endgroup$ – knzhou Aug 25 '18 at 4:55
  • $\begingroup$ @knzhou what do they mean by that: Mass distribution for the two-photon channel. The strongest evidence for this new particle comes from analysis of events containing two photons. The smooth dotted line traces the measured background from known processes. The solid line traces a statistical fit to the signal plus background. The new particle appears as the excess around 126.5 GeV. The full analysis concludes that the probability of such a peak is three chances in a million. $\endgroup$ – 0x90 Aug 25 '18 at 5:06
  • $\begingroup$ You quoted an entire paragraph. What part of it are you asking about? $\endgroup$ – knzhou Aug 25 '18 at 5:07
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The spin and parity of the particle detected can be measured by measuring the spins of the decay products, and the result is that the spin is zero. See this CERN article for more details.

If there were a spin half higgsino hiding alongside the higgs it would be easily detectable, so we can be confident that the observed resonance is a single spin 0 particle.

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  • $\begingroup$ Is it possible that the resonance is of 2 bosons? $\endgroup$ – 0x90 Oct 4 '17 at 7:05
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    $\begingroup$ @0x90: It would have to be a resonance of two identical bosons, and if the bosons are identical then, well, they're the same particle. If you're asking whether the Higgs could be a composite particle then that possibility still exists but I'm not sure how seriously it is taken these days. $\endgroup$ – John Rennie Oct 4 '17 at 7:22

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