I What is the Madala boson at LHC?

[kodama]

anyone have any idea what the Madala boson that supposedly is found in LHC data?

obviously it is proposed to explain dark matter, but it is a spin-0 field related to the Higgs.

claim is that Madala boson mediates the dark sector.

supposedly a 3-sigma excess at 270 GeVScientists predict the existence of a new boson: New Madala boson ...
Phys.Org-Sep 6, 2016
However, where the Higgs boson in the Standard Model of Physics only interacts with known matter, the Madala boson interacts with Dark

 

[ohwilleke]

A recent paper on the subject is here http://arxiv.org/abs/1606.01674 (the most recent one seems to be an abridged version of this one) and one of the earlier papers is http://arxiv.org/abs/1506.00612

The summary at the end of the recent paper states:

In this work we have presented the theory and rationale for introducing a number of new scalars to the SM. The particle content of the proposed model comes from a Type-II 2HDM, which predicts the scalars h, H, A and H ±, and two new scalars S and χ. The study follows a previous work (in Ref. [16]) which used H and χ to predict a distorted Higgs boson pT spectrum through the effective decay H → hχχ. In this work, the effective interaction is assumed to be mediated by the scalar S, and H is taken to be the heavy CP-even component of a Type-II 2HDM. The theoretical aspects of the equivalence between the effective model and the model presented in this paper is described in detail throughout section 2 and section 3. With these new scalars, it is clear that a great deal of interesting phenomenology can be studied. Within certain mass ranges, a variety of signatures of the model have been discussed. S, in particular is a key element in the model, since it acts as a portal to DM interactions through its S → χχ decay mode. It is also SM Higgs-like, and thus can be tagged through various decay modes. It is assumed to be produced mainly through the decay H → SS and H → Sh, and is therefore likely to produce events that come with jets, leptons and E miss T . In addition to the discussion on the model, a few selected leptonic signatures have been explored using MC predictions and event selections. Various interesting distributions have been shown, as well as the rates and efficiencies of some processes which have relatively small SM backgrounds. With the LHC continuing to deliver data at a staggering rate, it is important to keep testing models in the search for new physics. With a model dependence, experimentalists have a much clearer picture of what to look for in the data and how to bin results. It is evident that some hints exist in the search for new scalars at the LHC [16], and therefore the scalar sector is important to probe on both a theoretical and experimental level

 

[kodama]

do you think it's plausible? supposedly a 3-sigma excess this time at 270 gev

 

[ohwilleke]

No. That was 3 sigma after run-1. I'm pretty sure that the signals are weaker now and 3 sigma isn't even that big a deal once you consider look elsewhere effects, and the theory isn't terribly well motivated.

 

[Dr.AbeNikIanEdL]

I also don't really get how they come to the conclusion of $3\sigma$ in the earlier paper, from a statistics point of view. Why are they only considering one degree of freedom?

 

[kodama]

No. That was 3 sigma after run-1. I'm pretty sure that the signals are weaker now and 3 sigma isn't even that big a deal once you consider look elsewhere effects, and the theory isn't terribly well motivated.

yes I'm surprised there's no update on this 270 gev - recall 750 diphoton bump

but it's only *today* sept 7 2016 that all the physics news are reporting it

Scientists predict the existence of a new boson: New Madala boson ...
Phys.Org-Sep 6, 2016
The Wits Madala project team consists of approximately 35 young South African and African students and researchers who are currently ...
CERN LHC: New Madala boson predicted that interacts with dark ...
International Business Times UK-6 hours ago
Breakthrough 'Madala Boson' Could Unlock the Mysteries of Dark ...
Futurism-3 hours ago
http://www.dailygalaxy.com/my_weblog/2016/09/new-cern-lhc-experiments-predict-a-boson-beyond-the-higgs-that-could-unlock-clues-to-dark-matter.html
The Daily Galaxy (blog)-Sep 6, 2016
A 'God particle' called Madala
Local Source-Times LIVE-Sep 5, 2016
Researchers claim 'Madala boson' could help explain dark matter
In-Depth-Daily Mail-Sep 6, 2016

 

[ohwilleke]

The science press responds to press releases and somebody issued one even though there is no good reason to think that this is more promising than it was yesterday.

 

[Dr.AbeNikIanEdL]

There is also an "official" statement:

https://twitter.com/CERNpress/status/773509832485769216

 

[kodama]

The science press responds to press releases and somebody issued one even though there is no good reason to think that this is more promising than it was yesterday.

I also don't really get how they come to the conclusion of $3\sigma$ in the earlier paper, from a statistics point of view. Why are they only considering one degree of freedom?

the paper was based on a diphoton in 2015 run at 272 gev - i think the paper was reporting what LHC cern was reporting.

on aug 2016 cern reported no deviations from SM, no SUSY no 750 diphoton

 

[Dr.AbeNikIanEdL]

the paper was based on a diphoton in 2015 run at 272 gev - i think the paper was reporting what LHC cern was reporting.

I am pretty sure there was no $3\sigma$ excess at $270~\mathrm{GeV}$ in 2015 data. The paper does a combined fit to a large variety of observables, diphoton spectra amongst them. But all measurements they use are in agreement with the SM.

 

[ohwilleke]

Sometimes a paper submitted earlier gets a press release when it is published in a journal, resulting in a time lag.

 

[kodama]

I am pretty sure there was no $3\sigma$ excess at $270~\mathrm{GeV}$ in 2015 data. The paper does a combined fit to a large variety of observables, diphoton spectra amongst them. But all measurements they use are in agreement with the SM.

The compatibility of LHC Run 1 data with a heavy scalar of mass around 270\,GeV
Stefan von Buddenbrock, Nabarun Chakrabarty, Alan S. Cornell, Deepak Kar, Mukesh Kumar, Tanumoy Mandal, Bruce Mellado, Biswarup Mukhopadhyaya, Robert G. Reed
(Submitted on 1 Jun 2015 (v1), last revised 15 Nov 2015 (this version, v2))
The first run of the LHC was successful in that it saw the discovery of the elusive Higgs boson, a particle that is consistent with the SM hypothesis. There are a number of excesses in Run 1 ATLAS and CMS results which can be interpreted as being due to the existence of another heavier scalar particle. This particle has decay modes which we have studied using LHC Run 1 data. Using a minimalistic model, we can predict the kinematics of these final states and compare the prediction against data directly. A statistical combination of these results shows that a best fit point is found for a heavy scalar having a mass of 272+12−9\,GeV. This result has been quantified as a three sigma effect, based on analyses which are not necessarily optimized for the search of a heavy scalar. The smoking guns for the discovery of this new heavy scalar and the prospects for Run 2 are discussed.

 

[Dr.AbeNikIanEdL]

Yes, that is the paper @ohwilleke linked and I was talking about... ?

 

[Vanadium 50]

First, any physicist can write a phenomenology paper. Make predictions, discuss the agreement with data, whatever.

What is not done is for a subset of an experiment, in this case ATLAS, to claim a discovery in that experiments' data. When one joins an experiment, one joins a collaboration that has set up procedures for what needs to happen for the experiment as a whole to claim discovery - for example, there may be an internal group whose job it is to check the claim before going public.

In this case, there are three possible sources for the discovery claim.

One is the researchers themselves. If this is the case, they have demonstrated a lack of scientific integrity, and ATLAS is well within its rights to remove them from the collaboration. They may have little choice.

A second is the press office of Wits. If this is the case, it means they did not clear it with the researchers, and got the story wrong. This is sloppy to the point of incompetent. It would be entirely appropriate for the DG of CERN to call the VC of Wits and explain how bad this makes Wits look.

The third possibility is that both the Wits press office and the researchers got the story right, and the sources that repeated it screwed it up. That means those sources have no qualms about and no protection from posting stories that are false. In that case, why should we believe anything those outlets ever write?

 

[ohwilleke]

I strongly suspect that your second hypothesis is the most likely. University, press offices, particularly when issuing releases about scientific findings, routinely botch reports of their own researchers in ways that cross lines that the researchers themselves never would, and exaggerate the significance of the new findings. PhD comics ran a "so true its hilarious" run of comics about the phenomena a year or two ago, and I'd considered finding them and incorporating them in my original post. For example, this one: https://tapastic.com/episode/18523

In my experience, while secondary media outlets utilizing a press release sometimes compound the errors in the original press release, about 90% of the distortion applies at the level that the press release creates relative to the original research and perhaps 10% of the distortion arises in select retellings, mostly because only a handful of media outlets have staff who have the resources and intellectually capacity to expand much on the original material. That kind of analytical consideration of new results is normally limited to expertise only found in the blogosphere of physics/science bloggers and Internet forums such as this one (outside formal scientific publication, of course, which generally just ignores press releases entirely).

The trouble is that university PR office staff aren't really qualified to write intelligent press releasees on this stuff either much of the time, and have strong incentives to hype new research from their institution even if that hype is unjustified, because it can drive positive benefits for the institution (like donor and legislator enthusiasm for future research funding) even if the results are actually overhyped.

 

[Vanadium 50]

Here is what the authors say in their report to their sponsors:

Physics today is at a cross roads similar to the times of Einstein and the fathers of Quantum Mechanics. It is now clear that the physics understanding of the Universe is ostensibly incomplete. The discovery of the Higgs boson at the Large Hadron Collider (LHC) in 2012, which was awarded the Nobel Prize in physics in 2013, has opened the way to even more ground breaking discoveries: the observation of new bosons that are linked to forces and particles unknown before. The data reported by experiments at the LHC show strong hints of the existence of new bosons.

The experiments at the Large Hadron Collider (LHC) display a number of hints in their data that are indicative of the existence of new bosons. One of these bosons, the Madala Boson was hypothesized by the High Energy Physics (HEP) group of the University of the Witwatersrand. The discovery of new bosons would be a revolution in physics and would have implications reaching further than the discovery of the Higgs boson in 2012. These new bosons could explain the origin of unknown mass in the Universe and unveil new forces in nature.

The significance of the discovery of new bosons goes beyond that of the Higgs boson. The Higgs boson was needed to complete the Standard Model of Particle Physics. However, this boson did not signify the discovery of a new force or family of particles. The discovery of new bosons would be\ evidence for forces and particles formerly unknown. Therefore, and without a reasonable doubt, the discovery of new bosons would be worth a Nobel Prize in Physics.

The plot below on the left gives the evidence for the Madala boson with a mass around 270 GeV. This plot is the result of a phenomenological study performed by the HEP group at Wits. If confirmed with new data, this prediction would lead to a ground-breaking discovery, a South Africa-led discovery. The plot below on the right is the evidence for a boson around 750 GeV recently reported by the ATLAS experiment. The SA-ATLAS group has contributed directly to the results reported by the ATLAS collaboration.

The Wits press release says:

Using data from a series of experiments that led to the discovery and first exploration of the Higgs boson at the European Organization for Nuclear Research (CERN) in 2012, the group established what they call the Madala hypothesis, in describing a new boson, named as the Madala boson. The experiment was repeated in 2015 and 2016, after a two-and-a-half year shut-down of the Large Hadron Collider (LHC) at CERN. The data reported by the LHC experiments in 2016 have corroborated the features in the data that triggered the Madala hypothesis in the first place