String theorists, will the LHC see SUSY and if not, will this be a huge blow?

[Coin]

The point is, not seeing SUSY won't necessarily harm string theory---it just means that its broken at a higher scale.

Hm, okay. So would you say then that string models without SUSY are just not in the cards, period?

 

[Micha]

With what data? Beter values of Lambda? A higgs mass to three decimal places?

You are probably right, as far as experimental high energy physics is concerned. Also I am not saying, I particularly would like this outcome.

I was talking about theoretical physics.

As an example:
What data did Einstein need to develop GR?
Zero. He unified Newtons gravity with SR.

What data did he have to develop SR?
Zero. (Arguable, ok)
He in fact noticed that the transformation properties of classical mechanics
and Maxwells theory were inconsistent.

What data did Newton use to develop classical mechanics?
Zero. He unified Keppler's theory of the planitary motion with Galilei's theory
of falling bodies.

 

[George Jones]

Hm, okay. So would you say then that string models without SUSY are just not in the cards, period?

From Becker, Becker, and Schwarz:

"The third general feature of string theory is that its consistency requires supersymmetry, which is a symmetry that relates bosons to fermions. There exist nonsupersymmetric bosonic string theories (discussed in Chapters 2 and 3), but lacking fermions, they are completely unrealistic. The mathematical consistency of string theories with fermions depends crucially on local supersymmetry. Supersymmetry is a generic feature of all potentially realistic string theories. The fact that this symmetry has not yet been discovered is am indication that the characteristic energy scale of supersymmetry breaking and the masses of supersymmetry partners of known particles are above the experimentally determined lower bounds."

 

[BenTheMan]

You are probably right, as far as experimental high energy physics is concerned. Also I am not saying, I particularly would like this outcome.

I was talking about theoretical physics.

As an example:
What data did Einstein need to develop GR?
Zero. He unified Newtons gravity with SR.

What data did he have to develop SR?
Zero. (Arguable, ok)
He in fact noticed that the transformation properties of classical mechanics
and Maxwells theory were inconsistent.

What data did Newton use to develop classical mechanics?
Zero. He unified Keppler's theory of the planitary motion with Galilei's theory
of falling bodies.

Ahh...but who would have believed GR if it weren't for the experimental predictions. Almost immediately, Eddington tested GR's predictions that light follows geodesics, and the perhelion of mercury was derived.

Writing something down isn't the problem. Getting everybody to believe it's correct is always the issue.

From Becker, Becker, and Schwarz:

"The third general feature of string theory is that its consistency requires supersymmetry, which is a symmetry that relates bosons to fermions. There exist nonsupersymmetric bosonic string theories (discussed in Chapters 2 and 3), but lacking fermions, they are completely unrealistic. The mathematical consistency of string theories with fermions depends crucially on local supersymmetry. Supersymmetry is a generic feature of all potentially realistic string theories. The fact that this symmetry has not yet been discovered is am indication that the characteristic energy scale of supersymmetry breaking and the masses of supersymmetry partners of known particles are above the experimentally determined lower bounds."

This string scale supersymmetry, which we could never test at an accelerator. If SUSY is broken at a very high scale, then there is no way we'd know about it.

 

[Haelfix]

Theres nothing preventing SuSy from being broken at higher scales, other than naturalness and minimalism. It so happens (maybe a historical accident) that its a good model for stabilizing the electroweak scale (the original motivation).

If naturalness goes out the window, people will need to figure out better constraints from somewhere else (probably astrophysics/cosmology), unfortunately it is unlikely we will see something as strong and scale independant in our lifetime absent some unforseen theoretical breakthrough.

So like I said, high energy physics in the LHC disaster scenario will become the poorly funded domain of theorists. The ILC will be built b/c there is still some residual political will (a remant imo of the cold war) to do such a thing, but its unlikely another will be built after that unless there really is a compelling breakthrough.

 

[nrqed]

So like I said, high energy physics in the LHC disaster scenario will become the poorly funded domain of theorists. The ILC will be built b/c there is still some residual political will (a remant imo of the cold war) to do such a thing, but its unlikely another will be built after that unless there really is a compelling breakthrough.

I am surprised by this. What countries do you feel stil have this will? After the cancellation of the SSC (which was planned to be even more powerful than the LHC and therefore seemed like a good bet for some form of new physics or at least dicovery of the Higgs) it seemed to me that the US will not be a major source of funding for any future large accelerator. I am not sure that even a consortium of countries will have the will and means to invest billions and billions of dollars. But that's just an impression I have and I may be completely off target.

 

[BenTheMan]

The ILC will be built b/c there is still some residual political will (a remant imo of the cold war) to do such a thing, but its unlikely another will be built after that unless there really is a compelling breakthrough.

Seriously? You're talking about the same Democrats that just CUT funding for high energy physics?

After the cancellation of the SSC (which was planned to be even more powerful than the LHC and therefore seemed like a good bet for some form of new physics or at least dicovery of the Higgs) it seemed to me that the US will not be a major source of funding for any future large accelerator.

I think that the best that we can hope for is something like SUSY at the LHC. Honestly---there will then be a strong case to make for the ILC, which is a precision experiment, not an energy experiment. If this can be couched in a way that US politicians (thick skulled as they can be) can actually COMMIT to funding, then we MAY get an ILC in 30 years.

Either that, or we'll put more ant farms in space.

 

[jal]

I think that the best that we can hope for is something like SUSY at the LHC.

How about something else.
http://arxiv.org/abs/0707.2923v1
The Odderon at RHIC and LHC
Authors: Basarab Nicolescu
(Submitted on 19 Jul 2007)
Abstract: The Odderon remains an elusive object, 33 years after its invention. The Odderon is now a fundamental object in QCD and CGC and it has to be found experimentally if QCD and CGC (Color Glass Condensate) are right. In the present talk, we show how to find it at RHIC and LHC. The most spectacular signature of the Odderon is the predicted difference between the differential cross-sections for proton-proton and antiproton-proton at high s and moderate t. This experiment can be done by using the STAR detector at RHIC and by combining these future data with the already present UA4/2 data. The Odderon could also be found by ATLAS experiment at LHC by performing a high-precision measurement of the real part of the hadron elastic scattering amplitude at small t.
=====
QGP (quark-gluon plasma ) Is still a phase that needs experimentation if we ever want to be able to tap into this kind of energy.

 

[BenTheMan]

QGP (quark-gluon plasma ) Is still a phase that needs experimentation if we ever want to be able to tap into this kind of energy.

I don't know what kind of ``energy'' there is to tap into.

 

[Haelfix]

"Seriously? You're talking about the same Democrats that just CUT funding for high energy physics?"

I'm talking about the type of people who decided to fund a manned mission to Mars for no apparent reason whatsoever other than essentially technological welfare and pie in the sky wishful thinking. I guess thats as good a reason as any, and better than most, but yea that type of mentality fortunately still exists in some sectors of politics (in the US and even in the rest of the world). Hell it wouldn't surprise me if some super wealthy billionare decided to cofund it somewhere down the line.

Imo -and I may be wrong- it will take more than one failure down the line to stop the dream that particle accelerators give people.

 

[BenTheMan]

I'm talking about the type of people who decided to fund a manned mission to Mars for no apparent reason whatsoever other than essentially technological welfare and pie in the sky wishful thinking. I guess thats as good a reason as any, and better than most, but yea that type of mentality fortunately still exists in some sectors of politics (in the US and even in the rest of the world).

Fair enough---I really hope you're right. Nothing would be better for science in the US than an multi-national, multi-billion dollar high energy science lab. I really hope to see ILC data before I die.