CMS: Beyond all possible expectations

After having retraced the entire Standard Model up to the Top, the CMS collaboration is ready to go further and continue the success of what Guido Tonelli – its spokesperson – defines as a ‘magic year’. Things evolve fast at CMS, but scientists have taken up the challenge and are ready for the future.


‘Enthusiasm’ is the word that best describes the feeling one gets when talking to Guido Tonelli. “In just a few months we have rediscovered the Standard Model and have gone even further by producing new results for cross-sections, placing new limits on the creation of heavy masses, making studies on the excited states of quarks, and seeking new resonances. We could not have expected so much such a short space of time. It’s fantastic”, he says. “We went through the learning phase very smoothly. Our detector was very quickly ready to do real physics and we were able to start to produce results almost immediately. Thanks to the good amount of data provided by the LHC, we have already exceeded the Tevatron’s limits for some of the most massive objects. In the realm of Supersymmetry, we hope soon to be able to say something important in terms of excluding the existence of new particles over a large range of mass or, on the other hand, discover them”.

The first proton run has just finished and the data analysis is advancing very fast. “With hundreds of tops and many thousands of W and Z bosons having been produced, everything is ready to probe new physics. We have already observed an unexpected correlation between charged particles that come out of the collisions; we very carefully study the signals hinting at the production of new particles every day to see whether there are even very subtle effects due to new processes. The LHC and our detector are working so well that, by next year already, we could really be able to say something new on the Higgs boson”, enthuses Tonelli.

In the meantime, CMS is also running with ions. Technical adjustments will certainly be necessary, particularly to the software that reads out the sub-detectors and, of course, in the data analysis as the ion-ion collisions produce many more particles than the proton-proton collisions. “Although our detector is optimized to study the results of the collisions between protons, we believe that we will be able to confirm whether or not the quark-gluon plasma will be created and also which are, eventually, its gross properties”, he confirms.

After the Christmas technical stop, CMS is looking forward to starting a new proton run, which promises to be as exceptional as the first one. The centre-of-mass energy has not been decided yet but each additional TeV provided by the LHC will significantly increase the chances of the experiments observing heavy objects and probing extra dimensions. “Until a few months ago I wanted to remain conservative because I could not believe that things could go so well and so fast. However, now there are really no reasons for not being enthusiastic. Of course, this also means a very heavy workload as we can’t exclude any channel from our data analysis. We want to carefully investigate everything we observe, and we must keep pace. In order to do so, we are also restructuring our teams so that we have enough flexibility to be able to adapt to changing needs. The CMS collaboration is still growing and becoming even more global, with Egypt recently joining and Thailand expressing serious interest. The new members are focussing in particular on the development of R&D programmes for the CMS upgrade that will be needed in the near future”, concludes Guido Tonelli.

by CERN Bulletin