A Quantum Diaries Survivor

I am quite happy to report today that the CMS experiment at the CERN Large Hadron Collider has just published a new search which fills a gap in studies of extended Higgs boson sectors. It is a search for the decay of the A boson into Zh pairs, where the Z in turn decays to an electron-positron or a muon-antimuon pair, and the h is assumed to be the 125 GeV Higgs and is sought for in its decay to b-quark pairs. If you are short of time, this is the bottomline: no A boson is found in Run 1 CMS data, and limits are set in the parameter space of the relevant theories. But if you have a bit more time to spend here, let's start with the beginning - What's the A boson, you might wonder for a start. 

This one is definitely too juicy to ignore - I need to join the crowd of bystanders-in-awe. As you may have heard, ESA's ROSETTA spacecraft successfully landed yesterday on the solid nucleus of comet 67/P, Churyumov-Gerasimenko - a 2.5 mile long conglomerate of rock and ice. I refrain from giving detail of that enormous achievement for humankind, because I rather want to comment on this rather funny twist of the whole story. But still let's first enjoy at least one nice picture of the surface of that distant solar system body...

Forget the Higgs Boson, the Landing on Comets, Missions to Mars, the Genome Project, Nanostructures and all that. This start of this new millennium looks like the dark ages to me if I have to gauge it from discussions I overhear in public places. 

Results of a new search for single top production and large missing energy have been published by the ATLAS collaboration in a recent preprint. I think it is worthwhile to have a look at the idea behind this new search, as the signature of invisible particles produced in LHC collisions and escaping the detectors is important in many of the current and future investigations of beyond-the-standard-model physics.

The Large Hadron Collider at the CERN laboratories in Geneva is currently in shutdown, finalizing the upgrades that will allow it to restart next year at the  centre-of-mass energy of 13 TeV - over 60% more than the last 8 TeV run. ATLAS and CMS have collected no more proton-proton collisions since almost two years ago; yet the collaborations are as busy as ever producing physics results from the analysis of the 2012 data.Rather than focusing on any single result, below I give some highlights of the most recent publications by CMS. Another post will discuss ATLAS results in a few days.

I am spending a few days in Aix Les Bains, a pleasant lakeside resort in the French southwest, to follow the works of the second ECFA workshop,
titled "High-Luminosity LHC". ECFA stands for "European Committee for
Future Accelerators" but this particular workshop is indeed centred on
the future of the LHC, despite the fact that there are at present at
least half a dozen international efforts toward the design of more
powerful hadron colliders, more precise linear electron-positron
colliders, or still other solutions.

Yesterday the ATLAS collaboration published the results of a new search for dark matter particles produced in association with heavy quarks by proton-proton collisions at the CERN Large Hadron Collider. Not seeing a signal, ATLAS produced very tight upper limits on the cross section for interactions of the tentative dark matter particle with nucleons, which is the common quantity on which dark matter search results are reported. The cross section is in fact directly proportional to the rate at which one would expact to see the hypothetical particle scatter off ordinary matter, which is what one directly looks for in many of today's dark matte search experiments.

Do you remember the E-Cat ? That is an acronym for "energy catalyzer", the device invented by the Italian philosopher Andrea Rossi. The E-Cat is claimed to produce nuclear energy through the heating of a "secret" powder made up of nichel, hydrogen, and lithium plus some additives. A new chapter was added to the saga of the E-Cat this week, with the publication of a new study by an allegedly independent group of Italian and Swedish researchers.

"Fermilab has very actively tried to scoop us by press release, even though their uncertainties are under serious challenge and they knew our measurements even before they released theirs."Michael Riordan, a member to the Mark II collaboration, in an interview by David Perlman on the San Francisco Chronicle, July 21st 1989

I wonder how interesting can be to an outsider to learn that the mass of the sixth quark is now known to 0.38% accuracy, thanks to the combination of measurements of that quantity performed by the CMS experiment at CERN. In fact, the previously best measurement was the one recently published by the DZERO collaboration at Fermilab, which has a relative 0.43% accuracy. "So what" - you might say - "this 14% improvement does not change my life". That's undeniably true.

Last Friday Samuel Ting, the winner of the 1975 Nobel prize in Physics for the co-discovery of the J/ψ particle, gave a seminar in the packed CERN main auditorium on the latest results from AMS, the Alpha Magnetic Spectrometer installed on the international space station.

Being at CERN for a couple of weeks, I could not refrain from following yesterday's talks in the Main Auditorium, which celebrated the 90th birthday of Herwig Schopper, who directed CERN in the crucial years of the LEP construction.A talk I found most enjoyable was John Ellis'. He gave an overview of the historical context preceding the decision to build LEP, and then a summary of the incredible bounty of knowledge that the machine produced in the 1990s.