A new Boson?

[Brian37]

Seems as good a time and place as any to put this here...

I would have ended the song with, "Nothing really matters, Laurence Krauss can see, nothing really matters, to me".

[Alex K]

Good idea, different vid

[Alex K]

So, today were the presentations giving updates of the searches for the potential new boson. They didn't have much in the way of new data because like last year, the LHC had a winter shutdown and will only restart around Easter. Still, one of the experiments only now incorporated some data that were previously excluded due to technical difficulties. Analyses of old data were improved for better sensitivity. There are rumours of another unpublished analysis which shows an even bigger signal, but all in all, the significance in the official analyses went up a bit, but only further measurements starting in a few weeks will be able to clarify whether we are witnessing the biggest revolution in fundamental physics for decades, or just a statistical freak.

[ignoramus]

Explain a little better for us laypersons please.
Are you saying there might be other unique unknown particles where none were predicted via the maths previously?

[Alex K]

Explain a little better for us laypersons please.
Are you saying there might be other unique unknown particles where none were predicted via the maths previously?

Exactly. The Higgs boson was expected because the theory needed it or something like it, but after that the maths was complete, simply speaking, and it's not clear whether there are new particles to discover. Dark matter is the clearest hint that there should be new particles. This one can't be the dark matter because it obviously decays - but it could be related to dark matter and enable us to discover it.

If the signal is real, It would require an entirely new theory which would open up unexpected possibilities for research. There are many ideas what it could be of course.

[Jehanne]

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...

One is reminded of the Opera experiment:

https://en.wikipedia.org/wiki/OPERA_experiment

[Brian37]

I was watching a PBS special on CERN, and in it they discussed the supersymmetry vs chaos, if I remember correctly.

But again, correct me if I am wrong but the superssymmetry is really nothing more than religion trying to co opt science to justify a god of the gaps argument?

And according to this article "supersymmetry" is not doing very well as a theory.

http://phys.org/news/2015-07-supersymmet...heory.html

[Alex K]

Jehanne,

the Opera neutrino time of flight measurement was rather different in character for several reasons - first of all it was just one number, a timing measurement. The LHC detectors register complex events, in this case with two high energy photons coming out of a collision, and there is little doubt that the excess as seen has indeed occurred - the one opera timing number was off because of a faulty connector. Events as we see them here cannot just be faked by a simple fault in the machine like a loose wire. One more difference: having a new particle that would make such a signature in the LHC is theoretically quite plausible (i.e. it is not hard to write down a mathematically consistent model that produces such effects) whereas I myself have published a paper back in the day showing that it is basically theoretically impossible to have superluminal neutrinos the way Opera seemed to observe them for reasons I can go into if you're interested.

The Opera superluminal neutrino measurement was wrong due to a loose optical connector, this signal here is probably nothing because it will turn out to be an accidental statistical upward fluctuation rather than a systematic error in the experiments.

[Jehanne]

Jehanne,

the Opera neutrino time of flight measurement was rather different in character for several reasons - first of all it was just one number, a timing measurement. The LHC detectors register complex events, in this case with two high energy photons coming out of a collision, and there is little doubt that the excess as seen has indeed occurred - the one opera timing number was off because of a faulty connector. Events as we see them here cannot just be faked by a simple fault in the machine like a loose wire. One more difference: having a new particle that would make such a signature in the LHC is theoretically quite plausible (i.e. it is not hard to write down a mathematically consistent model that produces such effects) whereas I myself have published a paper back in the day showing that it is basically theoretically impossible to have superluminal neutrinos the way Opera seemed to observe them for reasons I can go into if you're interested.

The Opera superluminal neutrino measurement was wrong due to a loose optical connector, this signal here is probably nothing because it will turn out to be an accidental statistical upward fluctuation rather than a systematic error in the experiments.

It was not, however, an overnight correction:

https://en.wikipedia.org/wiki/Faster-tha...no_anomaly

A significant number of physicists believed in their faster-than-light result for over an entire year, even to the point of replicating it.

[Alex K]

Jehanne,

the Opera neutrino time of flight measurement was rather different in character for several reasons - first of all it was just one number, a timing measurement. The LHC detectors register complex events, in this case with two high energy photons coming out of a collision, and there is little doubt that the excess as seen has indeed occurred - the one opera timing number was off because of a faulty connector. Events as we see them here cannot just be faked by a simple fault in the machine like a loose wire. One more difference: having a new particle that would make such a signature in the LHC is theoretically quite plausible (i.e. it is not hard to write down a mathematically consistent model that produces such effects) whereas I myself have published a paper back in the day showing that it is basically theoretically impossible to have superluminal neutrinos the way Opera seemed to observe them for reasons I can go into if you're interested.

The Opera superluminal neutrino measurement was wrong due to a loose optical connector, this signal here is probably nothing because it will turn out to be an accidental statistical upward fluctuation rather than a systematic error in the experiments.

It was not, however, an overnight correction:

https://en.wikipedia.org/wiki/Faster-tha...no_anomaly

A significant number of physicists believed in their faster-than-light result for over an entire year, even to the point of replicating it.

I can't confirm that anyone really believed it - It was too out there. That doesn't mean that many theorists, including myself, didn't entertain the possibility that it might be true for the sake of speculation and worked out the consequences for the fun of it. It really was a lot of fun to try and dream up consistent theory how neutrinos can be faster than light without violating all the other observations.

Many of the members of the experiment didn't even want to be on the initial publication. Of course you have to try to replicate it if your experiment produces an unexpected result - that doesn't have anything to do with believing in it - what else were they going to do? Of course they need to replicate it (in this case using modified beams optimized for measuring the timing signal) to gain a better understanding of their experiment and the source of the deviation. That it wasn't an overnight correction is only due to the fact that it took so long to identify the faulty connection that was the source of the deviation.