The BBC has a nice article about CERN’s Large Hadron Collider (LHC).
I’ve mentioned the LHC before, and what we expect will be its central role in providing insights into some of the biggest questions in particle physics and cosmology. Th…

As for the background, isn’t a theoretical calculation after all? I mean, perhaps the organisers of the Olympics expected it to be evaluated by the participants, from general collider parameters.

JD comment: It’s not the biases in the analysis that I worry about; data can always be reanalyzed with different assumptions. It’s that something important might slip past the cuts that they need to make, and never get recorded.

…reminders me of another thing: is someone out thare taking care of permanent backup of LEPI+LEPII data, just in case non MSSM analysis is needed? Same about tevatron, I hope.

Hate to squash your enthusiasm, but don’t expect much from the LHC Olympics. Why, you ask? It is a good idea, but it’s not being implemented in a realistic manner. There are many flaws inherent in theorists pretending to do experimenter’s tasks. But there is a really, really BIG one associated with the LHC Olympics. Namely, the folks in charge have not given the background associated with the signals they report. (Presumably because it would take too much time and computer power.) This means that one literally cannot do anything meaningful with the data. For example, they give a signal which is obviously associated with neutralino production. Unless one knows better, one would not realize that the signal rate they report is statistically insignificant. In other words, it is swamped by background events. It would never be reported and thus cannot be used in the determination of the underlying physics. The physics reality of the LHC is much more complicated than what is being represented in the LHC Olympics. I wouldn’t expect any data-driven theorists to waste their time participating.

Jacques last comment is important. It is one of the arguments (I think) that it is useful to have a future International Linear Collider and the LHC running concurrently for some period, so that one could go back and, in principle, go back and run in some parameter region.

It won’t be easy to identify (once LHC is running) what kind of
supersymmetric standard model it is, if at all. There is a many-to-one
map, ie, one and the same set of given experimental data tends to
match many quite different discrete choices of parameters of the
supersymmetric standard model.

My understanding is that’s largely because there are so few independent “signals” that they can measure at the LHC. And we’re mapping a very high-dimensional parameter space into this low-dimensional signal space.

(This is also rather discontinuous map, as various channels open up, or shut off, as you twiddle the parameters of the theory.)

On top of that, each of the
groups seem to have their own class of pet models they focus on. I
wonder how one could possibly find something unexpected in this
manner.

It’s not the biases in the analysis that I worry about; data can always be reanalyzed with different assumptions. It’s that something important might slip past the cuts that they need to make, and never get recorded.

1) It won’t be easy to identify (once LHC is running) what kind of
supersymmetric standard model it is, if at all. There is a many-to-one
map, ie, one and the same set of given experimental data tends to
match many quite different discrete choices of parameters of the
supersymmetric standard model. This is partly because for a hadronic
collider, there are very many intermediate processes between the
original event and what you actually measure, to obscure the picture.
It seems to me that in order to do a thorough job, an enormous
effort plus luck will be necessary in order to meaningfully disentangle
the data.

2) It seems that most if not all of the analysis software is tuned
for the MSSM and variations thereof. On top of that, each of the
groups seem to have their own class of pet models they focus on. I
wonder how one could possibly find something unexpected in this
manner. I sensed a firm belief in “string inspired” MSSM’s (as if
there would be such a thing) and there was even the notion of
“scanning the M-theory parameter space”. I just hope that our
experimental collegues are independent enough such as not to be too
biased in favor what certain theoreticians tell them.

“Just recently I discovered, quite surprisingly, that raw experimental data obtained on CERN, including those that CERN scientists base their paper on, are top secret and classified material that outsiders are prohibited to obtain. ..”

I should clarify the situation. The raw data is the property of the collaboration (ATLAS, CMS LHCb etc.) which obtained it. This is standard practice in all particle physics experiments. It is fair as it will have taken ~2000 physicists over 15 years of effort to build the experiment and it is crucial that they get the payback for that. So it is only these people who have the right to analyse the data and present distilled results as public papers authored by the whole collaboration (acknowledging everyone’s contributions) which can then be used by the theoretical community. This also avoids the kind of situation where non-experimentalists try to use the data without an understanding of the intricacies of the data-taking environment or a knowledge of the experiment performance (which typically cannot easily be factorised out) and hence draw incorrect conclusions. It is the job of the experimentalists doing the data analysis to use their detailed specialist knowledge of such factors to correct for them and present data in journals in a format which can be used more easily by theorists to test specific phenomenological models.

The Grid is a tool which will be used for data analysis, and if your institute is participating then it may well end up receiving a small subset of the data for processing (’reconstruction’). This is not the same as saying that you have the freedom to then analyse that data yourself and write independent papers on it however. The data is passed straight back to the central collaboration for merging with all the other data and analysis by experimentalists in physics analysis working groups.

“Just recently I discovered, quite surprisingly, that raw experimental data obtained on CERN, including those that CERN scientists base their paper on, are top secret and classified material that outsiders are prohibited to obtain. ..”

So where did you discover that ? Ever heard about the Grid project ?

One semantic point about Higgs physics as the “origin of mass” as it is usually referred to. Firstly (and this is a point Wilczek likes to make) most of the mass around us, in the form of protons and neutrons, is largely insensitive to Higgs physics, and comes from QCD. Also, discovering the Higgs will probably leave the pattern of masses (flavor physics) mysterious. I think “origin of mass” is a bit of a misleading slogan, the “origin of symmetry breaking” is better, since it forces one to discuss symmetry breaking (as you have done) which is a fascinating concept.

best,

Moshe

Just recently I discovered, quite surprisingly, that raw experimental data obtained on CERN, including those that CERN scientists base their paper on, are top secret and classified material that outsiders are prohibited to obtain. That’s by the confession of some one inside CERN. I always thought those experimental data are open for any member of the public to obtain and study, as long as one is willing to compensate for the cost of retriving and delivering those information. But that is not the case.

Quantoken

Good luck.

Do you very excellent physicistes know of a bookie who would take such bets. (Restricted to the LHC turning these such somethings up, in the first instance.)