Turning 60

Strange how time goes by. And strange I would say that, since I know time does not flow, it is...

On The Illusion Of Time And The Strange Economy Of Existence

I recently listened again to Richard Feynman explaining why the flowing of time is probably an...

RIP - Hans Jensen

Today I was saddened to hear of the passing of Hans Jensen, a physicist and former colleague in...

2026 Plans

This year opened in slow motion for me, at least work-wise. I have been on parental leave since...

Tommaso Dorigo

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 »

Plot Of The Week - Quark Compositeness Is Nowhere Near

Oct 25 2010 | comment(s)

The CMS experiment has just released a new result which excludes the possibility that quarks have a substructure at energy scales below 4 TeV. The result comes from the analysis of just a handful of inverse picobarns of collision data -2.9 to be precise- and shows excellently just how well suited are the LHC collisions for this business. The limit is extended by over one TeV above the former result of the Tevatron experiments, and some 600 GeV above the results of the ATLAS collaboration, who also recently reported on their search for of quark compositeness in 7 TeV collisions, finding a limit at 3.4 TeV.

Electron Scattering And The Proton Structure

Oct 24 2010 | comment(s)

Week number one of my course on Subnuclear Gauge Physics is over. I think that in the first five hours of lesson I have given to my students a reasonable picture of the early experimental attempts and theoretical developments aimed at understanding the structure of atomic nuclei and individual nucleons with electron scattering. So I thought I might try and simplify the picture further, to reach a wider audience here. Of course, the topic is not terribly entertaining, unless one understands fully just how important these studies are for fundamental physics even nowadays -despite having started over 60 years back.

What's Going On Around

Oct 23 2010 | comment(s)

Swamped by my course of Subnuclear Gauge Physics, I have little time left to surf the web and keep an eye on what happens in the blogs I usually visit. Nevertheless, today is Saturday and I have allowed myself a short tour. Below is a list of the most interesting things I have read.

First of all, there's an interesting new blog out there, with experimental particle physics explained to laymen. The language is not English, but it is a language you should learn, too.

How Wide Is The Top Quark?

Oct 19 2010 | comment(s)

As 2010 nears its end, the Tevatron experiments feel the monopoly of top quark physics being taken from their hands, due to the good news on the running of the Large Hadron Collider. The ATLAS and CMS experiments there have started to mine their datasets, now amounting to over 20 inverse picobarns and growing significantly by the day. These datasets contain as many top quark pairs as half an inverse femtobarn worth of Tevatron collisions, due to the 20-fold higher cross section of top pairs at the LHC.

The Say Of The Week

Oct 17 2010 | comment(s)

"Since two fermions cannot turn into three fermions, the experimental observation of three-jet events in e+e- annihilation, first accomplished by the TASSO collaboration in June 1979 and confirmed by the other collaborations at PETRA two months later, implies the discovery of a new particle. Similar to the quarks, this new particle hadronizes into a jet, and therefore cannot be a color singlet. These three-jet events are most naturally explained by a hard noncollinear bremsstrahlung

. [...] Thus the 1979 discovery of the second gauge particle, the gluon, occurred more than fifty years after that of the photon. This particle is also the first [...] gauge particle with self-interactions.

LHC Breaks Into 10^32 Territory!

Oct 14 2010 | comment(s)

Quite in advance with respect to the stated goals of its 2010 collider program, the Large Hadron Collider has produced yesterday night the instantaneous luminosity of 10^32 cm^-2 s^-1 in the core of the ATLAS and CMS detectors. This is great news for all of us: at such a collision rate, on average one top quark pair is produced every minute, and one 120 GeV Higgs boson (if the thing exists) every 10 minutes makes its apparition there! (Calculations are in this recent post).