The Madala boson hypothesis was formulated by a small group of physicists two years ago. The idea was to explain various strange effects observed in data recorded during the first Run of the Large Hadron Collider, the LHC, at CERN.
[image credits: CERN]
In a few words, this new boson is a kind of heavy cousin of the Higgs boson with different properties.
Adding this boson to the theory allows one to fit the LHC Run I data in a better way than as within the Standard Model of particle physics alone.
However, two years ago, there was not enough information collected by the LHC to be able to either reject the guy or definitely confirm its existence.
Today, more data is available, as the second run of the LHC is on-going. It is thus timely to confront the Madala boson hypothesis to fresh data and see whether it survives or whether it should be sent to the graveyard of dead theories.
This is what has been done in this paper that I have read at the end of last week.
THE MADALA STORY - THE SETUP
The story of the Madala boson starts with data recorded during the LHC Run I, and the investigation of Higgs results.
[image credits: CERN]
A bunch of researchers from Johannesburg started to re-analyze eight of the LHC analyses connected to the Higgs boson.
First, it is important to recall that the results of all these eight analyses were found in perfect agreement with the Standard Model of particle physics.
However (there is always a ‘however’), data comes with error bars, as for the theory predictions. We must thus be very careful with the interpretation of the results (in particular when one claims for a discovery or the rejection of a hypothesis).
Even if data and the Standard Model were agreeing with each other pretty well, the confrontation of the theory to the experimental results was not able to fully exclude the presence any non-standard effect.
THE ORIGIN OF THE MADALA BOSON HYPOTHESIS
The results of the eight chosen analyses were actually exhibiting a bunch of interesting features and excesses that would deserve a deeper look.
This is how the story really started. The South African researchers were planning to confront a new physics model to data, to see whether any improvement regarding the strange features was in order.
But what was this model?
[image credits: homemade]
The model under consideration is very simple. We take the Standard Model and extend it with one new scalar boson ‘H’.
The capital ‘H’, that is a slightly different symbol as the one used for the Higgs boson (‘h’), can be seen as a second Higgs boson and has been named by the South African researchers the Madala boson.
Moreover, the model also features a dark matter candidate that is connected to both the Madala boson and the Higgs boson.
It was hoped that having both a Madala boson and a dark matter particle would help to get a better agreement between the observed properties of the Higgs boson and the theory.
I however insist once again, the theory-data agreement without the dark matter and Madala guys is already pretty good. We are talking about trying to improve things here.
THE MADALA THEORY AND THE LHC RUN I DATA
A couple of years ago, the results of the exercise have been published here. The findings were very interesting and are summarized in the picture on the right.
[image credits: arXiv:1506.00612]
When the Madala theory is confronted to data, it turns out that there is a preferred value for the mass of the Madala boson H of around 270 GeV. This is more than twice the mass of the Higgs boson.
Just be explain a little bit more: the best fit value on the figure on the right is the minimum of the chi-square curve.
The conclusions of their article were pretty clear: extending the Standard Model of particle physics by a new heavy scalar boson and a dark matter particle allows to improve the agreement between theory and data. The preferred mass value for the Madala boson is found to be 270 GeV.
One important question remained at that time: although the agreement with data was better, there was no direct evidence in the LHC Run I data to support the existence of the hypothetical Madala boson.
THE MADALA THEORY AND THE FRESH LHC RUN II DATA
In the article that I have read last week, the same group from Johannesburg investigated whether the Madala hypothesis was surviving LHC Run II data collected so far. They explored this time both Run I and Run II Higgs results.
What they found is that the new best fit value is compatible with the Run I results taken alone, once uncertainties are accounted for. It also seems that the no-Madala-boson hypothesis is disfavored with respect to the Madala-boson-hypothesis.
Once again, it is still to early to be able to firmly disentangle the two hypotheses, but what is important to bare in mind is that the Madala model is still well alive.
SUMMARY AND REFERENCES
In this article, I discussed a few mild anomalies in LHC Higgs boson data. While those anomalies are compatible with the Standard Model of particle physics when uncertainties are accounted for, it is interesting to double check which room is left for having some new phenomena hidden there.
This is the whole story of the Madala boson hypothesis. We take the Standard Model, add a heavy cousin of the Higgs boson and a dark matter candidate. We mix everything and confront it to data. In this case, an improvement with respect to the Standard Model is found. However, it is still too early to claim for anything: we are still missing a direct observation of the new boson. This will maybe (or maybe not) come in a couple of years… We need in any case to stay tuned! :)
One image has nothing to do with the topic. A small reward for who finds it (and give the reason why it has nothing to do with the post)!
For more information, I recommend to read the original Madala boson article available in open access here, as well as the update with respect to fresh data available there.
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