If LHC reports no SUSY by Aug 2016 data set

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Main Question or Discussion Point

according to blogger
Tommaso Dorigo

the LHC
"What to expect for ICHEP

I believe that if the machine keeps delivering at this pace, by mid-July CMS and ATLAS could have in their hands some 10 inverse femtobarns of 13-TeV collisions. Those data, three to four times larger in size that what was collected in 2015"

so with 10 inverse femtobarns + 3 inverse femtobarns from 2015, which was a null for SUSY, 13 total inverse femtobarns by July

LHC found no SUSY ie gluinos squarks in the 2015 run, if LHC finds no SUSY in the current 2016 run, which will reported in the Aug 2016 what are the prospects LHC will ever find SUSY?

what would a null result on SUSY with 13 inverse femtobarns at 13 TEV say about SUSY as the solution to the hiearchy problem
 

Answers and Replies

  • #2
then we have to wait for the chinese super collider in 2020. It's twice as big as the LHC
 
  • #3
MathematicalPhysicist
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Why do some (or is it most?!) theoretical physicists believe in the existence of SUSY?
 
  • #4
ChrisVer
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1. I am not sure, but I guess SUSY has nothing to fear from LHC... it can be there even if it's not found by the collider... why? because theorists need it. SUSY is a very large field/theory, what we are searching and rejecting are just "low-energy SUSY models", at least for the theoreticians.
2. Now about SUSY models and the hierarchy problem; I guess the more complex or extreme you make the model, then you can still give it some hit-points before dying... the more complex a model is though, the more we tend not-to-like it.
3. If it's not found with the 2016 data collection, then we'll have to search for even weaker signals.

4. Why do theoretical physicists believe in the existence of SUSY: because it's nice.
"Believing" is the right word that can trigger a "because it's nice" answer.
 
  • #5
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1. I am not sure, but I guess SUSY has nothing to fear from LHC... it can be there even if it's not found by the collider... why? because theorists need it. SUSY is a very large field/theory, what we are searching and rejecting are just "low-energy SUSY models", at least for the theoreticians.
2. Now about SUSY models and the hierarchy problem; I guess the more complex or extreme you make the model, then you can still give it some hit-points before dying... the more complex a model is though, the more we tend not-to-like it.
3. If it's not found with the 2016 data collection, then we'll have to search for even weaker signals.

4. Why do theoretical physicists believe in the existence of SUSY: because it's nice.
"Believing" is the right word that can trigger a "because it's nice" answer.
what is the upper limit for gluino/squark masses before SUSY ceases to be a valid explanation for higgs hiearchy problem? bounds are already past 1500gev for gluinos, and LHC may raise those bounds to 2600gev
 
  • #6
MathematicalPhysicist
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1. I am not sure, but I guess SUSY has nothing to fear from LHC... it can be there even if it's not found by the collider... why? because theorists need it. SUSY is a very large field/theory, what we are searching and rejecting are just "low-energy SUSY models", at least for the theoreticians.
2. Now about SUSY models and the hierarchy problem; I guess the more complex or extreme you make the model, then you can still give it some hit-points before dying... the more complex a model is though, the more we tend not-to-like it.
3. If it's not found with the 2016 data collection, then we'll have to search for even weaker signals.

4. Why do theoretical physicists believe in the existence of SUSY: because it's nice.
"Believing" is the right word that can trigger a "because it's nice" answer.
We should have a better criterion than "it's nice".
 
  • #7
ChrisVer
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We should have a better criterion than "it's nice".
It was just a nasty comment for anybody who would go as far as believe in a theory that has no experimental verification so far... I am not saying that it's not happening, quiet a few theoreticians don't really care about the experiment. In their view, there's no problem with sending the SUSY up to the Planck Scale, because for what they do SUSY is essential and "nice". Their goal of SUSY is to make their equations work and not to solve any physics problem (like the Higgs Hierarchy problem)...although I am not very certain about the last, maybe they can find an weird explanation within a very-exotic SUSY-derived model.

what is the upper limit for gluino/squark masses before SUSY ceases to be a valid explanation for higgs hiearchy problem? bounds are already past 1500gev for gluinos, and LHC may raise those bounds to 2600gev
First of all, I don't know the limits.
I do know though that you have to specify which SUSY model we are talking about. The MSSM has, I think, already been rulled out as a possible candidate for the hierarchy problem solver (at least with the current Higg's mass if that Higgs is the SM boson as all the results indicate, then I'd say that the MSSM has already lost the game. However making it too exotic can still keep it alive). It's not the same for NMSSM, which has more freedoms...
 
  • #8
725
84
It was just a nasty comment for anybody who would go as far as believe in a theory that has no experimental verification so far... I am not saying that it's not happening, quiet a few theoreticians don't really care about the experiment. In their view, there's no problem with sending the SUSY up to the Planck Scale, because for what they do SUSY is essential and "nice". Their goal of SUSY is to make their equations work and not to solve any physics problem (like the Higgs Hierarchy problem)...although I am not very certain about the last, maybe they can find an weird explanation within a very-exotic SUSY-derived model.


First of all, I don't know the limits.
I do know though that you have to specify which SUSY model we are talking about. The MSSM has, I think, already been rulled out as a possible candidate for the hierarchy problem solver (at least with the current Higg's mass if that Higgs is the SM boson as all the results indicate, then I'd say that the MSSM has already lost the game. However making it too exotic can still keep it alive). It's not the same for NMSSM, which has more freedoms...
NMSSM seems like an ad hoc solution.

if NMSSM is falsified theorists can cook up the NNMSSM and the NNNMSSM by simply adding more particles and fields to evade experimental falsification

ok. if SUSY does not stabilize the hierarchy problem, does this mean

1- the SM ins comformally invariant or
2- naturalness in the higgs sector is a misguided criterion?
 
  • #9
I think there is a misunderstanding in the debate
SUSY isn't important for theoretical physicists. It's only important as advanced SM for particle physic phenomenology.

For the theoretical physicist is only important Photon, Axion, Dilaton and Graviton in combination with Gopakumar-Vafa Invariants and Gromov-Witten Invariants e.g.
SUSY doesn't matter for the theoretical physicist
 
  • #10
ChrisVer
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ok. if SUSY does not stabilize the hierarchy problem, does this mean

1- the SM ins comformally invariant or
2- naturalness in the higgs sector is a misguided criterion?
I am not so much in theoretical physics so I don't understand what you mean by SM being conformally invariant...
As for 2. Well, it was one of the supporting ideas for SUSY because SUSY appeared to solve that... but hey, you yourself say that adding an extra scalar field (to go from MSSM to NMSSM) sounds as an ad hoc solution, why doesn't the idea of adding for each particle an extra sparticle not sound the same? MSSM in fact sent the overall particle content to double the one we know today...
When you want to deal with a problem in general you have to keep in mind some stuff; like is that problem really a problem? if you think that it is, you continue and build a model that could potentially solve this and be still "ok" with observations. So you get several models, 1 of which is also the one presented here:
http://arxiv.org/pdf/hep-ph/0506256v2.pdf
(or ittle Higgs Models)
which actually postpone the problem up to a few TeV.
 
  • #11
ChrisVer
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SUSY isn't important for theoretical physicists.
Well most [personally all] of the string theories I've heard about incorporate SUSY. I don't know if that is part of string phenomenology, just saying.
 

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