Supersymmetric theories predicted that the elementary particles of the standard theory of particle physics (leptons, quarks, photon, gluons, W- and Z-boson, Higgs boson) have supersymmetric partners. This supersymmetric particles (called neutralinos, photino, gluinos, Winos, Zinos, squarks, and sleptons) were all predicted to have rest masses between 50 and 300 GeV (billion electron volts).

Now the ATLAS Collaboration of the LHC (Large Hadron Collider) presented data (arXiv: 1102.2357) which do not confirm the gluino. It would have been detected if its rest mass were less than 700 GeV.

I am not so surprised that signs of light supersymmetric particles have not been detected. I predict that supersymmetry will not be confirmed. My arguments are the following.

(1) The main reason for supersymmetry is that it can explain some shortcomings of minimal Grand Unified Theories, i. e. the mass-hierarchy problem (i. e. the fact that W- and Z-boson do not have rest masses of 10^15 GeV, although they should have “eaten” (coupled to) the Higgs bosons of Grand Unification) and the non-observation of the proton decay (lower limit: mean proton lifetime of 10^33 years).

But this argument requires that there is Grand Unification.

In 1997 I suggested (Modern Physics Letters A 12, 3153 – 3159 = hep-ph/9708394) a generalization of quantum electrodynamics, called quantum electromagnetodynamics. This theory is based on the gauge group U(1) x U’(1). In contrast to QED it describes electricity and magnetism as symmetrical as possible. Moreover it explains the quantization of electric charge. It includes electric and magnetic charges (Dirac magnetic monopoles) and two kinds of photon, the conventional Einstein electric photon and the hypothetical Salam magnetic photon. The electric-magnetic duality of this theory reads:

electric charge — magnetic charge
electric current — magnetic current
electric conductivity — magnetic conductivity
electric field strength — magnetic field strength
electric four-potential — magnetic four-potential
electric photon — magnetic photon
electric field constant — magnetic field constant
dielectricity number — magnetic permeability

Because of the U(1) x U’(1) group structure and the Dirac quantization condition e * g = h (unit electric charge times unit magnetic charge is equal to the Planck constant), this theory is hard to agree with Grand Unification. Although a group such as SU(5) x SU’(5) is in principle not impossible.

(2) Another reason for supersymmetry is that it can explain the existence of (anti-symmetrical) fermions in an otherwise symmetrical theory (such as Special Relativity and General Relativity).

However, it has long been known that a generalization of General Relativity which includes anti-symmetry is Einstein-Cartan theory. The affine connection of this theory includes not only the non-Lorentz invariant symmetrical Christoffel symbol but also the Lorentz invariant anti-symmetrical Torsion tensor.

Within the framework of a quantum field theory, the Torsion tensor corresponds to a spin-three boson called tordion, which was introduced in 1976 by F. W. Hehl et al.: Reviews of Modern Physics 48 (1976) 393 – 416.

In 1999 I discussed (International Journal of Modern Physics A 14, 2531-2535 = arXiv: gr-qc/9806026) the properties of the tordion. Moreover I sugested that the electric-magnetic duality is analogous to the mass-spin duality. This analogy reads:

electric charge — magnetic charge – mass — spin

electric field constant — magnetic field constant — gravitational constant — reduced Planck constant

electric four-potential — magnetic four-potential — metric tensor — torsion tensor

electric photon — magnetic photon — graviton — tordion

(3) Supersymmetric theories including superstring and M theory have not much predictive power. For example, so far no one has shown that these theories predict the empirically obvious Naturkonstanten-Gleichung (fundamental equation of unified field theory, Modern Physics Letters A 14, 1917-1922 = arXiv: astro-ph/9908356):

ln (kappa * c * H * M) = −1 / alpha

where kappa is the Einstein field constant, c is the speed of light, H is the Hubble constant, M is the Planck mass, and alpha is the fine-structure constant. By using the WMAP−5 value

H = (70.5 +/- 1.3) km / (s * Mpc)

(E. Komatsu et al.: Astrophys. J. Suppl. Series 180 (2009) 330 – 376) the left-hand side yields

ln (kappa * c * H * M) = – 137.025(19)

which is within the error bars equal to

- 1 / alpha = – 137.035 999 679(94)

The Naturkonstanten-Gleichung predicts the Hubble constant to be

H = 69.734(4) km / (s * Mpc)

It is true that ATLAS and CMS have used totally different approaches, though, for their first papers. It is true that CMS, in its first paper, elected to use “alphaT”, a variable that it acnkowledges has strong QCD rejection but only weak sensitivity to SUSY. This was (it seems to me) a descision based on a desire to be able to create a robust analysis that could discover SUSY very quickly if it was very easy to see. Nothing wrong with that. You could call it a “conservative approach”.

ATLAS, on the other hand, decided to go all out (from the beginning) with an analyses that was designed to go for something approaching maximum reach, right from the start. As a consequence, ATLAS used a totally different approach, eschewing alphaT in favour of variables like m_eff and m_T2 with much greater sensitivity to SUSY. Indeed, at ICHEP in Paris, last year, CMS people suggested to me that CMS was likely to produce a m_eff or m_T2 based paper thenselves on the first year’s data. Whether they still will do this, I do not know. If they do produce such a paper it will (most probably) have a very similar reach to that of ATLAS.

So to conclude, the difference in the reach between ATLAS and CMS is nothing to do with “MC” versus “Data-Driven” BG estimates — it is to do with one having done an analysis using “Apples” and the other having used “Oranges”. AlphaT is just not optimised for SUSY discovery. CMS openly admit this in section 4.4 their paper

http://arxiv.org/pdf/1101.1628v1

where they say

“Both these variables [Meff and deltaPhi [a surrogate for m_T2]] exhibit differences between SUSY signal events and events from SM backgrounds and could, therefore, be used to improve the limits extracted in the following section. We have chosen not to do so because the current search has been optimized for the demonstration of a potential new signal, rather than for the extraction of the most stringent limits in the SUSY parameter space.”

I wasn’t aware that ATLAS and CMS used such different methods—when you say MC vs. data-driven, I’m assuming you mean for calculating the background? Is there a way to quantify how reliable/unreliable the Monte Carlo is relative to the data-driven technique?

-F

It is unfortunately misleading.

See slides 12, 21 and 23 of

http://indico.cern.ch/contributionDisplay.py?sessionId=31&contribId=44&confId=103979

I suspect the answer is no. Broadly speaking there are two things that we need to study new at high scales: (1) high energies, (2) lots of data, i.e. “high luminosity.” I imagine that just taking more data will make a difference by decreasing statistical uncertainties.

Of course, if the squarks/gluinos are really heavy, then our only shot is to make sure that we’re getting enough events at high enough energies. Since the actual “pointlike” interactions are between quarks which don’t necessarily carry the entire momentum of the proton, each proton/proton collision has less energy that 3.5 + 3.5 TeV. So having more luminosity at 7 TeV will increase the number of high energy events… but certainly not as much as having more luminosity at a higher center of mass energy.

The relation between center of mass energy and sensitivity is not obvious to me, though. (It might be obvious… just not to me!) The background is different at different energy scales, so maybe it gets much better, maybe it gets worse.

As Lubos says, though, when we start pushing the bounds to around a TeV scale or so, people will start sweating about the fate of low energy supersymmetry.

Anyway, the summary is that I’m sorry I can’t answer this better. Perhaps the following links (and links therein) might have more to say:

http://www.math.columbia.edu/~woit/wordpress/?p=3462
http://resonaances.blogspot.com/2011/02/what-lhc-tells-about-susy.html

Does the meff[GeV] axis scale roughly linearly with collision energy? What I mean is, if the collision energy goes up to 14TeV does that then give you data right up to the 1200 to 1400 area? If so, it must have made the decision to stay at 7TeV for another year a really difficult one.

I know you’ve already seen (and commented) on Jester’s post, but for others: Resonaances has a very nice blog post on these results:

http://resonaances.blogspot.com/2011/02/what-lhc-tells-about-susy.html

Best,
Flip

If you want to see the parameters where one really waits for the LHC to make a verdict – and where it will start to bite the “real meat” – see e.g. the parameters of the surviving Indian supersymmetric island:

http://motls.blogspot.com/2010/12/surviving-indian-supersymmetric-island.html

Gauginos around 900 GeV. You are not too far from this point. The LHC could have discovered SUSY in the very early months. It hasn’t happened. But it’s still very far from falsifying the points that were likely based on the latest pre-LHC, including Fermilab, data. If and when you publish an upper limit that goes to a TeV, I will begin to be nervous.

For an update on science in the White House FY2012 budget proposal, here’s a summary from Peter Woit: http://www.math.columbia.edu/~woit/wordpress/?p=3455