A new Boson?

[Alex K]

Giving this its own thread, now.

There has been interesting news from CERN yesterday about the data they have taken with increased collision energy this year. It has transpired that the two largest experiments  fed by the LHC beam, ATLAS and CMS, both see an excess of events with two photons at roughly the same energy, 750 GeV.  This is what the ATLAS data look like



Just for comparison, this is what the Higgs boson looked like in its two photon signature at some point (now the statistics is better)



Each experimental deviation by itself would not get  physicists to raise an eyebrow, because if you look in enough different places in the data, such fluctuations are likely to occur, even expected. But to see compatible excesses at the same energy in both experiments, which are statistically completely independent, that is something worth having a closer look at. Should one get cautiously excited? I don't know, seemingly astonishing signals have gone away in the past when more data was collected. If it is really a new particle, it is bound to be something special - another Boson. If it has spin 2, it is groundbreaking, because we will either have found some unexpected form of quantum gravity and maybe new dimensions of space, or a composite particle of a composition hitherto unknown to science, which would open the door to a phantastic new world of discovery. If it  has spin 0, it might be a bigger brother of the Higgs boson, which could revolutionize our understanding of the origin of the Higgs boson itself. One of the big puzzles in fundamental physics is how the Higgs boson - theoretically - manages to be so light when it should be pushed to much higher masses by its interactions with virtual particles. A second scalar boson is bound to shed light on this issue.

A new particle is always a potential gateway to an entirely new "world". For example, while we have not been successful to detect dark matter until now, such a new boson - while it cannot form dark matter itself because it decays - might be the key to finally connect to this dark side of the universe: in several proposed theory hypotheses, such a boson is the link between the known particles we are made of, and a "dark" sector.

Probably only the enhanced experimental statistics of the next LHC run in 2016 will tell, but people will now comb through the existing data whether one can find traces of such a new particle in different particle constellations that have been overlooked because one didn't specifically look for such a signature.

In any case, such a discovery would be the first discovery of a new particle in 40 years that was not already expected theoretically and via indirect observations like the Higgs - a completely new chapter in physics - if it is true...