Everyone in the particle physics community is avidly awaiting the startup of the LHC accelerator at CERN, scheduled for 2007. A new preprint by Gianotti and Mangano entitled LHC physics: the first one–two year(s) gives some idea of what to expect.
The design luminosity for the LHC is about 1034cm-2s-1, which is about 100 times the current luminosity of the Tevatron. Current plans are to first cool down the machine in spring 2007, followed by commissioning single beams over the next few months, with first colliding beams in the second half of 2007. During 2007, most effort will be devoted to commissioning the machine, followed by a shutdown for a few months. A seven-month long physics run at luminosities of up to 2 x 1033cm-2s-1 will take place during 2008. This is 20 times the current Tevatron luminosity and the Tevatron seems to be averaging a total of about 15 pb-1 per week, so one could expect a total luminosity of up to about 10 fb-1 to be collected during 2008. This is probably much too optimistic. Experience with the Tevatron when it was turned on at the beginning of its latest run was that for quite a while it was running at only a tenth of the hoped for luminosity. So perhaps 1 fb-1 during 2008 is a more realistic expectation.
According to Gianotti and Mangano, 1 fb-1 will be enough to see squarks and gluinos at masses of up to about 1.5 Tev. Seeing the Higgs is more demanding, especially if its mass is low. If its mass if above 180 Gev, it should require 5-10 fb-1, if it is just above the LEP limit (114 Gev) it is likely to require more like 20 fb-1.
Personally I think it’s quite unlikely the LHC will be seeing supersymmetric particles, so, of the things it is looking for, it will require good luck to get the data required to see the Higgs during 2008. Even if this does happen, I’d guess that analyzing the data would take us into 2009. If the LHC has trouble getting anywhere near design luminosity, things could take longer. Of course everyone hopes that something completely unexpected will be found. If this is dramatic enough, maybe there will be some exciting news in 2008.
TL – fun paper!
-drl
Completely off-topic, but a nice historical paper anyway: physics/0504179. From the introduction one deduces that Ivan Todorov is not a big fan of string theory. But we knew that anyway, from some comment in one of Bert Schroer’s assaults long ago.
Is there some theoretical posibility for a observed violation of SM in the LHC?
Some time ago I read about the posibility for a four family!!
Neutrino experiment in Minnesota mine..
-drl
Hi JC,
As another commenter mentioned, I’ve written about this before in various places. Basically the minimal supersymmetric extension of the standard model (MSSM) is much more complicated and ugly than the standard model, introduces nearly 100 new free parameters, generically has problems with flavor-changing neutral currents and proton decay. The only real argument for it is the coupling constant unification calculation, and that’s not that convincing. The popular “hierarchy stabilization” argument never seemed very convincing to me (and has technical problems besides, see the so-called “mu problem”. Many of the landscape artists have already happily abandoned the idea of using supersymmetry to stabilize the hierarchy. Now of course anthropic reasoning explains all such things.
“If its mass if above 180 Gev, it should require 5-10 fb-1, if it is just above the LEP limit (114 Gev) it is likely to require more like 20 fb-1.”
This already means exciting times if the Higgs sector is not minimal. Say there is a particle at exactly 246 GeV… people would hail it as “the Higgs” and then when going down successive particles of the sector should appear. Funny.
Until Peter answers JC’s question, readers might want to look at an earlier posting of Peter’s entitled, “Attack on the Main Argument for Supersymmetry.”
http://www.math.columbia.edu/~woit/blog/archives/000025.html
The fact that I can pick out this old citation off the top of my head tells me I’m probably spending too much time at this site, but I enjoy it!
Peter,
What are your main objections to supersymmetric extensions to the standard model?
Ignoring GUTs, my main objection is that SUSY seems to be a symmetry that is just imposed by decree, with very little to no convincing experimental basis. The picture of the coupling constants converging to a “possible” single point with SUSY, isn’t entirely convincing. All the arguments I’ve heard of over the years used to justify SUSY seem to be various aesthetic and/or theoretical “beauty” types of arguments, such as the coupling constants “converging” to a single point.
IF the universe was truly following some theoretical “beauty” type of principle, then why didn’t the experiments confirm the simple SU(5) GUT model? (This is one counterexample to the many silly theoretical “beauty” types of arguments).