This week results are being presented by the LHC experiments at the Moriond (twitter here) and Aspen conferences. While these so far have not been getting much publicity from CERN or in the media, they are quite significant, as first results from an analysis of the full dataset from the 2015+2016 run at 13 TeV, This is nearly the design energy (14 TeV) and a significant amount of data (36 inverse fb/experiment). The target for this year’s run (physics to start in June) is another 45 inverse fb and we’ll not start to hear about results from that until a year or so from now. For 14 TeV and significantly larger amounts of data, the wait will be until 2021 or so.
The results on searches for supersymmetry reported this week have all been negative, further pushing up the limits on possible masses of conjectured superparticles. Typical limits on gluino masses are now about 2.0 TeV (see here for the latest), up from about 1.8 TeV last summer (see here). ATLAS results are being posted here, and I believe CMS results will appear here.
This is now enough data near the design energy that some of the bets SUSY enthusiasts made years ago will now have to be paid off, in particular Lubos Motl’s bet with Adam Falkowski, and David Gross’s with Ken Lane (see here). A major question now facing those who have spent decades promoting SUSY extensions of the Standard Model is whether they will accept the verdict of experiment or choose a path of denialism, something that I think will be very damaging for the field. The situation last summer (see here) was not encouraging, maybe we’ll soon see if more conclusive data has any effect.
If the negative news from the LHC is getting you down, for something rather different and maybe more promising, I recommend the coverage of the latest developments in neutrino physics here.
Update: Lubos has paid off his bet with Jester. Losing the bet hasn’t dimmed his enthusiasm for SUSY. No news on whether David Gross has conceded his bet.
is it premature to declare SUSY dead?
since only 36 fb-1 @ 13tev was analyzed, with additional 45 fb-1 projected this year and 3000fb-1 overlifetime, is it still possible LHC will find SUSY?
what about a future HE-LHC or 100tev collider?
new — If an electron EDM is found then there is a good chance that a future collider will see something. As CP phases in new physics generate an EDM to the electron. Currently non-observation of electron EDM by ACME collaboration, puts generic SUSY scale to be above 8-10 TeV, which is out of LHC’s reach. Future improvements in sensitivity by an order of magnitude which is expected soon by ACME, and non-observation of electron EDM, will put SUSY scale above 30 TeV, out of reach of future colliders. Of course there could always be some particular SUSY models with suppression of CP phases where the electron EDM limits wont translate to limits on new Physics.
new — for reference for electron EDM impact on particle physics, please see slide 47 of https://indico.hep.anl.gov/indico/getFile.py/access?resId=0&materialId=slides&confId=791
I understand, one of the principal difficulties that high energy experimentalists face in LHC and beyond is that, there are some hundreds of millions of event/sec and their job is to find a needle in a haystack as they say! So there is too much reliance on known theoretical models in setting up triggers etc. The reason given is that there is not enough memory to store every event. While this is true, it may be that they could be missing phenomena which are not predicted by any existing theory. Admittedly this strategy worked very well for the discovery of Higgs. But for unknown physics it may be a handicap!
Yes, and this is one reason blogging here has been sparse (I’m also busy thinking about other things). Not a lot happening in HEP physics these days, with the release of LHC results getting zero attention just one aspect of the situation.
The problem is that further increases in luminosity only give you relatively small increases in energy reach (given a typical model). Current limits on gluinos are about 2 TeV. I don’t know the projected numbers for the energy reach of the HL-LHC, but I would guess it’s something like 2.5 TeV, no more than 3 TeV. So, sure, maybe there’s a gluino in between 2 and 2.5 TeV, but there’s no argument for this other than wishful thinking. The only argument people had for why the LHC should see a gluino was the fine-tuning argument that said it should have already been seen at the Tevatron. Similar comments apply to the energy reach increase of next generation accelerators. Anon is also right that the idea of superpartners just above the LHC limits is in conflict with the EDM measurements (and this was true pre-LHC, so one reason Jester and others felt there was a very good bet against SUSY even then),
Experimentalists are well aware of this issue, of the need to set triggers and do analyses which will be sensitive to a wide range of possible new phenomena, not just something with very specific properties. The possibility that something is being missed because it’s not being triggered on or not being looked for is something worth worrying about, and a good argument for considering as wide a range of models as possible, not concentrating on SUSY models.
anon – thanks for link i’ll look forward for new results on ACME. any idea when in 2017 it will be results will be announced?
peter – given the strongest argument for SUSY is fine-tuning argument and LHC has not seen SUSY, what is the likelihood SUSY exists but is broken at some higher energy scale?
Don’t know, but looks like they are currently taking data. ( link )
anon, the link you provide seems to suggest
Abstract: B2.00001 : ACME Measurement of the Electron Electric Dipole Moment
10:30 AM–11:00 AM Tuesday, June 6, 2017
Tuesday, June 6, 2017 newest results will be released
any word on the latest results on neutron and proton edm?
Electron EDM implies new physics would be found at next collider — but neutron and proton EDMs do not imply this….. this is bec. the strong CP Phase \theta contributes to neutron EDM and \theta can be generated due to physics at very high scales — like the seesaw scale (which could be at 10^14 GeV) or the Planck scale.
So finding neutron EDM, while important, does not imply there will be new physics to be discovered at next collider.
Dont know when the next nEDM expts will be reporting their new results — I believe in one expt, data collection is underway (but dont know if it will increase the sensitivity by much) — several other expts are planned around the world to run in next few years to increase the sensitivity by an order of magnitude.
Pingback: Quick Links | Not Even Wrong