A Quantum Diaries Survivor

This is a post about basics. That's because I think a point needs to be made which is surprisingly not as well-known as its elementary nature would have you guess.Correlation -in its most used version, due to Pearson- is a measure of how two quantities can be observed to be in linear dependence on one another. It is a very common quantity to report the results of scientific studies, particularly but not exclusively in the social sciences. Researchers try to evidence the presence of a correlation between two phenomena as a preliminary step to investigating whether one can be the cause of the other.

In High-Energy Physics the small p-value of an observation may be the first hint of a discovery about to be made. Here by p-value I just mean the probability, just to be fancy (or brief). Because we rely on the assessment of the rarity of observations to decide whether we have discovered something or not, we physicists are (or should be) really careful with p-values. Today's article aims at demonstrating how easy it is to be carried away into giving more relevance to an observation than we should.

A new preprint is out in the arxiv today, detailing the results of a new analysis of neutrino speeds performed by the OPERA collaboration using proton spills of the CNGS beam produced during dedicated runs in May this year.

The conceptual design report of the Mu2E experiment at Fermilab is out in the arxiv for you to browse. Mind you - it is a rather thick document, 562 pages in all, so if all you have is 15' of lunch break you have better try something lighter.

Update: I got a confirmation that at the latest INFN board of directors meeting the news was given that the Super-B factory to be built outside Rome is no more. Super-B joins other remarkable projects in high-energy physics -notably the SSC, the American 40-TeV super-collider to be built in Texas, and killed by Congress in 1993- in the dust bin.With this move the Italian government shows again how little they care for basic research in Italy, and provides further fuel to the escape of bright researchers to other countries.

The top quark is the heaviest of the six known hadron constituents, discovered at the Fermilab Tevatron collider in 1995.  Because of its quite large mass -over forty times more than the second-heaviest bottom quark- and because of a few additional interesting properties, the top quark has stimulated in the past two decades a large amount of theoretical work, well matched to the Tevatron investigations.In fact, one of the explicit goals of the CDF and DZERO experiments for Run II of the Tevatron, which lasted from 2002 to 2010, was to study extensively the top quark both as a standard model object, subjected as it is to electroweak interactions which can be studied and compared to predictions, and as a portal to new physics of various kinds.

UPDATE: BBC radio contacted me to let me know they corrected their mistake. I am very glad to hear that! So you can continue reading BBC after all!Probability inversion is one of the nastiest mistakes one can do handling the results of a statistical analysis, invalidating to the roots the interpretation of the data to the point that the whole work effectively becomes useless. Unfortunately, it is a very common entertainment for journalists reporting scientific results, and oftentimes scientists themselves fall in the trap.

Maybe more interesting than the just reported result of searches for the Higgs boson into four-lepton final states (ee, eμ, μμ) are the result presented by CMS and ATLAS on the searches for the Higgs decay into tau-lepton pairs. The reason for the interest comes from the fact that last July the rather high rates of Higgs decays to photon pairs had suggested to some that this new particle might have reduced couplings to fermions, and could thus be a non-Standard Model particle after all.

Today new results of Higgs searches have first been shown in Kyoto, at the Hadron Collider Physics conference. Let us see the CMS and ATLAS updates of their measurements in the ZZ-> 4 leptons final state, which constitutes the best signal-to-noise channel to study Higgs properties cleanly and measure mass and spin-parity of the new found particle.

The Hadron Collider Physics symposium opened yesterday in Kyoto. I am not following the works very closely, but I did give a peek at today's talks, which were on the topic of top quark physics.

It has taken a while, but the rare decay of B_s mesons (particles composed of a bottom and an anti-strange quark) to muon pairs has finally been seen. The authors of the find -we cannot yet call it an observation given the scarce statistical significance of the signal- are the members of the LHCb collaboration, one of the four experiments working with the proton-proton collisions delivered by the Large Hadron Collider at CERN.

I read the text below in the Facebook page of a colleague and friend, Christopher Hill. The text was meant as a facebook rant - sort of - but it raises important points. I liked what he wrote and I asked him if I could repost it here to the benefit of a larger audience. He graciously agreed. NB: the title of the post is mine.Now that the election and Sandy is (sort of) over, I want to post a rant that I didn't think was appropriate before now. First, Nate Silver. I have heard him called everything from a genius to a wizard to a witch in recent days. He is none of the above. He is a guy who understands mathematics (in particular statistics) enough to be able to use it to predict elections.