I watched in horror what happened in Turkey last month. I am very proud of my fellow Turkish countrymen. I admired their courage in the way they resisted that senseless coup. But, sadly my home country is now experiencing a deep existential trauma.
On the personal front, my professional career in the New York business world may be ending. Call it escapism or something else, I won’t address these traumas at this time. Instead, I will talk about the latest experimental findings in the physics world. There is trauma there as well.
I my previous post I mentioned that the Large Hadron Collider (LHC) is breaking all kinds of performance records. As of this writing, LHC has delivered more than 20 inverse femtobarns worth of proton-proton collisions to the ATLAS and CMS experiments each in 2016. That’s impressive performance! LHC is delivering on its promise in terms of beam intensity and number of collisions but unfortunately there is no sign of new physics beyond the Standard Model. The fear is growing that this very expensive marvel of technology and beam physics (my specialty in the old days) will not help us discover physics beyond the Standard Model of particle physics.
Latest ATLAS and CMS results were presented at the ICHEP 2016 in early August 2016.
“ATLAS and CMS have also looked for any signs of the direct production of new particles predicted by Supersymmetry and other exotic theories of physics beyond the Standard Model, but no compelling evidence of new physics has appeared yet. In particular, the intriguing hint of a possible resonance at 750 GeV decaying into photon pairs, which caused considerable interest from the 2015 data, has not reappeared in the much larger 2016 data set and thus appears to be a statistical fluctuation.” – CERN
Regarding the BSD (beyond-Standard-Model) 750 GeV particle (which turned out to be a false alarm) I recommend Adam Falkowski’s blogposts (here and here). The comments there convey the incredible disappointment among the particle physicists who were really hungry for new physics. I also recommend Natalie Wolchover’s article titled “What No New Particles Mean for Physics” at the Quanta magazine.
The latest LHC (ATLAS and CMS) findings are really bad news for the Supersymmetry. Latest experimental results established new (higher) lower bounds for the theorized supersymmetric particles. The lower bound for the gluinos is now 1.9 TeV, and the lower bound for the stops (supersymmetric partner of the t-quark) is now 1 Tev. The meaning of this is explained by Natalie Wolchover in her article mentioned above:
“Ultimately, supersymmetry becomes so “broken” that the effects of the particles and their superpartners on the Higgs mass no longer cancel out, and supersymmetry fails as a solution to the naturalness problem. Some experts argue that we’ve passed that point already. Others, allowing for more freedom in how certain factors are arranged, say it is happening right now, with ATLAS and CMS excluding the stop quark — the hypothetical superpartner of the 0.173-TeV top quark — up to a mass of 1 TeV. That’s already a nearly sixfold imbalance between the top and the stop in the Higgs tug-of-war. Even if a stop heavier than 1 TeV exists, it would be pulling too hard on the Higgs to solve the problem it was invented to address.” – Natalie Wolchover
Another bad news for the Supersymmetry came from the searches for dark matter particles. The LUX dark matter experiment which searches for the theorized WIMP (Weakly Interacting Massive Particle) announced null results. The WIMP proposal is related to Supersymmetry.
“LUX’s extreme sensitivity makes the team confident that if dark matter particles had interacted with the LUX’s xenon target, the detector would almost certainly have seen them. These new limits on dark matter detection will allow scientists to eliminate many potential models for dark matter particles, offering critical guidance for the next generation of dark matter experiments.” – LUX collaboration
I made a prediction about the non-existence of sterile neutrinos (if you define the “sterile neutrino” as having right-handed chirality) in this blogpost 1 year ago. I am not bragging because anyone can predict existence/nonexistence with 50% accuracy. But, just for fun, I insist on my prediction: future experiments will not find neutrinos with right-handed chirality either.