The Physics Advisory Committee at Fermilab have announced their decision to continue running the Tevatron until 2014. It is easy to see why they want to do that: This years published results have strengthened the case for a light Higgs sector. In the mass range up to 150 GeV the rival Large Hadron Collider does not have such a big advantage and wont make the Tevatron obsolete until around 2014 when it’s higher energy and luminosity will finally trump the Tevatron at all mass scales. In the meantime the Tevatron will double its current database of collision events which currently stand at around 9/fb, although Most of the results shown this year only used about 6/fb, so by the time they finish they will be using about three times the data. That should be enough to give a clear signal for where the Higgs mass lies. If there is a more complex Higgs sector with charged multiplets they should have a good indication of that too. According to Fermilab other exciting measurements include the search for supersymmetric Higgs bosons at large tanβ, measurement of the forward-backward asymmetry of the top quark, and the di-muon charge asymmetry in neutral B decay, as well as further improvement in the measurement of the top-quark and W-boson masses.
Any of these things would be an exciting discovery beyond standard model physics and would completely change the Tevatron’s place in history, so it is no surprise they want to go on, but in the grander scheme of things it is not such a good move. By 2014 the LHC will be surpassing the Tevatron and could well beat them to the most interesting discoveries. At best the Tevatron will share some of the glory unless the LHC has another significant failure that pushes back their schedule. Meanwhile, other experiments and developments at the Tevatron will not be able to progress so well, both because their budget suffers and because the Tevatron is needed to power them. This includes NOvA, LBNE, Mu2e, and Project X. For longer term progress in high energy physics it would be better if Fermilab concentrated on those efforts.
Meanwhile at CERN the planning council has approved a five-year plan that makes some significant cutbacks in their projects. During 2012 while the LHC is off-line for maintenance, they have now decided that all other experiments on the CERN complex will also be halted. This will push back future plans while allowing the medium term LHC goals to be unaffected. Studies for the next Linear Collider will be slowed and some planned upgrades to the LHC will also be delayed. This is seen as a short-term cutback due to harsh economic times but it could easily turn into a series of pullbacks from cash-strapped governments who are beginning to question the wisdom of expensive research with no direct payback.
It has been suggested that the LHC plans are ambitious with still an order of magnitude of improvements in luminosity to reach the 100/µb/s target by end of october. Even if they achieve this they will need another factor of two next year to be able to collect the 1/fb they want during 2011. But the LHC commissioning process has in fact been going very well with most targets they have set being reached or exceeded so far. Sometimes they face setbacks as they work to push the machine to new heights, but time can be made up as luminosity increases. For the last three weeks the LHC has made no physics runs while preparations are made for the next stage of running. In the next few days they will be colliding again with three major improvements. The separation between proton bunches will be reduced from 1000 µs to just 150 µs and a larger crossing angle of 100 µrad will be used at the collision points to keep the bunches apart before they meet. The speed at which the magnets can be ramped up to increase the beam energy has also been improved by a factor of three to give a significantly better turn round time between runs. With these changes it should be possible to step up the beam luminosity by adding more bunches in a veritable crescendo of activity before they switch to heavy ion physics in November.
The results of the next few years at the Tevatron and LHC will be critical for the future of fundamental physics. If the Tevatron and LHC find supersymmetry it will show that the theorists have been on the right lines for the lats few decades after all and we will see business as usual once again. If only the standard model is found the superstring doubters will come out in greater force and the impact on theoretical physics research around the world could be devastating, even though supersymmetry at the weak scale is not a definitive prediction. Other scenarios are possible if unexpected discoveries are made.