Moriond EW 2017 results -- No supersymmetry

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    2017 Supersymmetry
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Discussion Overview

The discussion revolves around the results from the 52nd Rencontres de Moriond EW 2017, particularly the implications of the absence of evidence for supersymmetry (SUSY) after analyzing 36 fb-1 of data at 13 TeV. Participants explore the consequences for various theoretical frameworks, including the Minimal Supersymmetric Standard Model (MSSM), natural SUSY, and string theory, as well as the broader implications for new physics and the Higgs hierarchy problem.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants note that results are consistent with the Standard Model (SM) and question the prospects of discovering SUSY with the remaining LHC data.
  • Others propose that the lack of SUSY findings raises questions about the viability of natural SUSY and its implications for the MSSM and nMSSM.
  • A participant mentions that projections from ATLAS and CMS suggest potential discoveries with 3000 fb-1, but also highlights specific mass ranges where gluinos have been ruled out.
  • There is a discussion on the relationship between SUSY and string theory, with some arguing that string theory does not necessarily imply low-energy SUSY breaking.
  • Another participant points out that there are non-supersymmetric string vacua that have been relatively neglected, suggesting a need for further exploration in this area.
  • Concerns are raised about the implications of not finding SUSY for theories like loop quantum gravity (LQG) and whether LQG can adequately address gravity.
  • Some participants emphasize the need for more research and training in LQG in light of the LHC results.

Areas of Agreement / Disagreement

Participants express a range of views on the implications of the LHC results, with no consensus on the viability of SUSY, the future of string theory, or the status of loop quantum gravity. The discussion remains unresolved regarding the broader implications for theoretical physics.

Contextual Notes

Participants highlight limitations in current theoretical frameworks and the need for further research, particularly in light of the LHC's findings. There are unresolved questions regarding the implications for the Higgs hierarchy problem and the nature of SUSY in various models.

kodama
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52nd Rencontres de Moriond EW 2017
présidé par Lydia Iconomidou-Fayard (LAL), Jean Marie Frere (ULB Brussels)

has released results based on 36 fb-1 data @ 13 TEV

they compare predictions from SUSY i.e squarks gluinos stops etc, with SM

all results consistent with SM 95%

No supersymmetry

given that most discoveries are found fairly early in data collection at hadron colliders
given they found no gluinos and squarks and supersymmetry in the first 36 fb-1 data
what are the propsects of ever finding these over LHC lifetime of projected 3000 fb-1 data

what are implications to MSSM and nMSSM that no SUSY was found.

what are implications to natural SUSY that no SUSY was found @ 13 TEV

is natural SUSY still viable or has data falsified it?

how does it affect SUSY and string theory that LHC has failed to find any evidence of SUSY after analyzing 36 fb-1 @ 13 TEV energies?

does solutions to Higgs hiearchy problem - SUSY technicolor extra dimensions require finding new physics @ LHC energies?LHC results are consistent with SM only. no evidence of technicolor or extra dimensions RS gravitons dark matter neutralinos SUSY were found by LHC either. what does this mean for higgs hiearchy problem that motivates new physics searches?
does not finding SUSY bolster loops LQG over strings?
 
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Read the papers. I know you will understand them.
Both ATLAS and CMS have public projections how much they can do with 3000/fb, and theorists have similar projections as well.
 
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mfb said:
Read the papers. I know you will understand them.
Both ATLAS and CMS have public projections how much they can do with 3000/fb, and theorists have similar projections as well.

one of the papers had a statement to imagine 3000 fb-1 @ 100 TEV resolving many issues.

another paper had a statement iirc that ruling out gluinos from 1200-1600 gev makes it impossible for a discovery in that mass range with 5-sigma

and one paper had a statement that 36 fb-1 @ 13 TEV allowed for better precision then the expected 14 TEV @ 3000 fb-1 on certain rule outs.
 
kodama said:
does not finding SUSY bolster loops LQG over strings?
Can I emphasize first that the preferred language for particle physics is field theory, not strings or loops. QFT is the language of the SM and of every BSM model that makes collider predictions.

String theory can definitely reduce to field theory. The search for a string model of reality, is all about that. LQG, on the other hand... Their main priority is still just, getting space-time itself. Then there are well-known problems like their peculiar method of quantization (polymer quantization), which doesn't even give you the simple harmonic oscillator as it appears in QFT, and their problems with fermions and black hole entropy.

String theorists have a vast space of models to explore. Loop theorists don't even have a functioning model that clearly reproduces any QFT at all, let alone the SM. The one thing in loop-world that interests me is the work on twistor networks, which might converge on the rewriting of QFT in twistor variables that grew out of Penrose's twistor program and Witten's twistor string.

About SUSY - that LQG usually doesn't feature SUSY, is mostly just another symptom of LQG's limitations. Regarding strings, yes string theory is full of SUSY, but there's nothing in string theory that implies SUSY breaking at low energies; people assumed that, and looked for it, because they thought it was the solution to the hierarchy problem. But strings can also have SUSY broken at high scales, or even no SUSY at all.
 
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How can strings have no SUSY at all since bosonic string theory doesn't describe our world.

Current experimental results is consistent with NO SUSY no extra dimensions. without either, there's no credible case for string theory.
 
There are actually vast numbers of non-supersymmetric string vacua. They contain fermions, and may exhibit SUSY-like relations between fermions and bosons, but are not supersymmetric. They have been relatively neglected because they are usually unstable, because SUSY makes calculation easier, and because SUSY just seemed too good to not be true; but they have been studied a little. This paper is a small step towards at a minimalism similar to nuMSM + asymptotic safety. They don't exhibit a model with just the SM fields (there are other papers heading in that direction), but they do tackle Higgs inflation.
 
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Any other news of Moriond? Everything is looking very SM-ish.
 
Still ongoing, and we'll have Moriond QCD after that. Nothing surprising so far.
 
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kodama said:
does not finding SUSY bolster loops LQG over strings?

No, because it is unclear if LQG has gravity.
 
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atyy said:
No, because it is unclear if LQG has gravity.

Penn state is AFAIK the only LQG program both faculty and training graduate students in US.

in light of LHC not finding any evidence of SUSY or any hints of BSM, even after collecting and analyzing 36 fb-1 @ 13 TEV perhaps it's time for the top physics departments in the world and research centers in Princeton, Harvard Stanford MIT UC Berkley et al, hire and train more loop LQG researchers so the issue of whether it is unclear LQG has gravity can be made more clear with more researchers and theorists and grad students working on this in both faculty and graduate programs.
 

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