A Quantum Diaries Survivor

One and a half years ago ATLAS produced measurements for the Higgs boson mass using their selected sample of H->gamma gamma and H->ZZ*-> 4-lepton decay candidates, based on data collected in 2011 and 2012. That preliminary measurement was rather surprising as the two independent determinations appeared to disagree with one another at the 2.5-sigma level. The matter even spurred some online debate (see e.g. my blog entry) and a few gambling addicts waged $100 on the fact that those might be two distinct particle states.

With still three months to go and 663 teams participating, the Higgs challenge has not even entered a hot phase yet, and still there is a lot to watch in the leaderboard at the kaggle site.In the last few days, there has been a total revolution in the leading position, and a considerable increase in the best scores. And Lubos Motl is again third (and he would be first if there had been no movement in the other positions), implicitly answering some detractors who wrote comments in a previous post on the matter here. See the standings below.

On my first day at the Erice School of Science Journalism this past week I attended a lecture by Alessio Cimarelli, who discussed "When Data Journalism meets Science: a "Hackathon"". The speaker (who owns the site called "dataninja") showed several examples of how to mine the web to construct databases and display results on several topics. It was quite interesting to see the techniques he used, but I felt compelled to interrupt him at some point, in the interest of the school participants.

I have spent the last few days at a School of Science Journalism in the pleasant town of Erice, in western Sicily. The school, held at the Ettore Majorana Centre for Scientific Culture, brought together science communicators, freelance writers, magazine editors and press office consultants to listen to a small set of lectures, which this year (the fifth of the school) centered on the topic of "the digital world".

Today among the three top players -those in the money- at the Higgs challenge we see the appearance of Lubos Motl, whom I had signalled as a participant in an earlier posting. We all know that Lubos is a smart guy, but I doubted whether he would take this very seriously. However, it seems he is. As we speak he has submitted almost 100 solutions (you can submit up to 5 solutions per day, so that means having worked at this at least 20 days in a row).
In the clip below you see the top standers from the challenge site's leaderboard:

You are the first to arrive to a dinner party and must choose the table where to sit, relying on your past experience of how handsome members of the opposite sex (you're straight) usually choose their seat. You need to buy stocks based on past performances and trends. You travel to some distant location and would like to know what's the weather like there, but there is no forecast for that particular place. What do you do ?

One of the nice details lost in the big picture of the Higgs boson discovery of 2012 is that a significant part of the signal put in evidence by ATLAS and CMS is produced by a very special kind of interactions between the protons accelerated by the LHC. These are "vector boson fusion" processes, whereby it is not the protons or its constituents that come in direct contact, but rather, each proton emits a W boson, and it is the latter pair which fuse together, give rise to a Higgs particle.

I reported here a few days ago about a very nice challenge issued by the ATLAS experiment: find Higgs boson decays to tau lepton pairs in a sample containing signal as well as background events, using a training sample with correct signal and background labels per each event.The challenge consists of solving a typical classification problem in a highly multidimensional space (30 dimensions) better than all other participants - the metric to judge being an "approximate median significance" of the subset of events that the user classifies as "signal". This is given by the formulaAMS = sqrt {2 * [(s+b+10) * log(1 + s/(b+10)) - s] }

I am spending the week in the pleasant resort of La Biodola, in the Elba island. Elba is a beautiful island just off the coast of Tuscany. Here Napoleon was exiled after his abdication in 1814 (he arrived here on May 30th). Exactly 200 years later, 100 Italian researchers have decided to exile themselves here to discuss the future 10 years of accelerator-based experiments, to understand where to "put their money", or better their research activities and efforts.

I came to know through a social network (I have many colleagues as friends there, and they usually post more useful stuff than cute kittens) that ATLAS has launched a very intriguing competition. One you can participate to, if you have some programming skills; no knowledge of particle physics is needed.The idea is to ask you to classify as signal (Higgs decay to tau lepton pairs, if you really want to know!) or background (anything that looks similar to it but involves no Higgs boson) a set of 550,000 events, for each of which ATLAS gives you 30 kinematical quantities measured in the detector (it is a simulation, but it's a pretty good approximation of reality).

Very recently, a combination of the precise measurements of the mass of the top quark obtained by the CDF and DZERO experiments at the Fermilab Tevatron collider with those produced by the ATLAS and CMS experiments at the CERN LHC collider has been produced, obtaining a result of 173.34 GeV, which surprised nobody -of course- with a very small total error bar: 0.76 GeV, a mere 760 MeV, not even a proton's mass.

This must be the boosted b-jets season... Just a few days ago I discussed here the nice new observation of boosted Z->bb decays pulled off by the ATLAS collaboration using 8-TeV proton-proton collisions recorded in 2012. And today I am pleased to see in the Arxiv a new study by D. Ferreira de Lima, A. Papaefstathiou, and M. Spannowsky on the possibility to measure the pair production of Higgs bosons in their decay to two pairs of b-quark jets.