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Toponium Found By CMS!

The highest-mass subnuclear particle ever observed used to the the top quark. Measured for the...

The Problem With Peer Review

In a world where misinformation, voluntary or accidental, reigns supreme; in a world where lies...

Interna

In the past few years my activities on this site - but I would say more in general, as the same...

The Probability Density Function: A Known Unknown

Perhaps the most important thing to get right from the start, in most statistical problems, is...

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Tommaso DorigoRSS Feed of this column.

Tommaso Dorigo is an experimental particle physicist, who works for the INFN at the University of Padova, and collaborates with the CMS and the SWGO experiments. He is the president of the Read More »

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Neutrino Telescopes XV

Neutrino Telescopes XV

Feb 14 2013 | comment(s)

Every two years physicists and astrophysicists who work in the area of neutrino physics get together in the wonderful setting of Palazzo Franchetti, a historical palace on the Canal Grande in Venice, Italy, to discuss the latest results of experiments and theoretical ideas, and to plan for the future.
The Quote of the Week - Peter Higgs: Inventing an Elementary Particle

The Quote of the Week - Peter Higgs: Inventing an Elementary Particle

Feb 13 2013 | comment(s)

I quickly wrote a short paper, "Broken Symmetries, Massless Particles and Gauge Fields", which described how gauge theories may evade the Goldstone theorem, and submitted it to Physics Letters. It was received on 27 July and published 15 September. Before writing up the work on what is now known the Higgs model I spent a few days searching the literature to see whether it had been done before. I thought that Schwinger, in particular, might well have done something of the kind years earlier and I might have overlooked it. When I had satisfied myself that he hadn't, I wrote a second short paper, "Broken Symmetries and the Masses of Gauge Bosons", and submitted it too to Physics Letters. It was rejected.
The Mysterious Y(4140)

The Mysterious Y(4140)

Feb 11 2013 | comment(s)

Quite some time ago I discussed here the tentative Y(4140) resonance  claimed by the CDF collaboration in their Run II data. This was a peak which was found in B-decay data containing a J/Psi signal, a phi meson, and an additional kaon track, and it resulted from the  study of the mass difference of the J/Psi + phi signal and the J/Psi alone.

Confused ? You have all rights to be. I will explain everything in good order, but be sure that the matter was puzzling not only for laymen but also for insiders: because the find was mysterious, not predicted by existing models, and potentially controversial.

B Decays and the CDF Claim
What's The Omega_b Mass? LHCb Confirms CDF, DZERO Way Off

What's The Omega_b Mass? LHCb Confirms CDF, DZERO Way Off

Feb 07 2013 | comment(s)

The Omega_b particle is a quite peculiar baryon, made up by three heavy quarks: a b-quark, and two s-quarks. Because of this composition, where only down-type quarks appear, the phenomenology of the decay of this particle is really spectacular: both the b-quark and the strange quarks take quite some time to decay, and as they take shifts to do it the Omega_b first transmutes into a Omega (a particle made up by three s-quarks!), then into a Lambda, and finally into a proton.

Each of these decays generates a reconstructable decay point, so one can reconstruct the whole chain perfectly. A sketch will clarify matters - see below.
On The CMS Higgs Video, Bias And Variance

On The CMS Higgs Video, Bias And Variance

Jan 31 2013 | comment(s)

Nowadays whenever I set out to write about CMS I turn on a self-censorship co-processor in the back of my mind, one which is instructed to check that all the sentences I write are completely free from any possible misinterpretation or slant that may cause some colleagues to complain. Oh, strike that, we're a big family and we all love each other.

The topic of today is in fact potentially explosive - how experiments perform their blind searches and the potential bias that results from the detailed procedures they employ. However, you will be disappointed by reading this article if you search for scandal and flame: I am going to explain why CMS does excellent science.
Tevatron Higgs Sensitivity: Did We Lie In 1999?

Tevatron Higgs Sensitivity: Did We Lie In 1999?

Jan 29 2013 | comment(s)

Today the arxiv features the paper describing the final word by the CDF experiment on its searches for the standard model Higgs boson. This paper supersedes previous ones describing searches performed in partial datasets and including only a subset of the decay channels that have been used, so if you are interested in knowing how CDF did in the end, that is the article to read. Or the present one, if you have less time to spend on the matter, or if you are interested in an ex-post evaluation of sensitivity predictions!