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Exploiting Nuisances

Today I am back from one of the most interesting workshops I ever attended to, and I wish to share...

The Magic Dimuon Decay Of B Mesons

To appreciate what B mesons are, and what is the magic of their behaviour, which is the topic of...

New Hadrons Decaying Into J/Psi Pairs

Physicists from the CMS experiment at CERN's Large Hadron Collider have used the total data sample...

A Fantasy In Db Minor

Now and then I find the time to write music for piano. It is a compelling, satisfying activity...

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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 experiment at the CERN LHC. He coordinates the European network... Read More »

And to complement the title: "...and what the heck is that, anyway?" 

The Italian "Accademia Nazionale dei Lincei" is an old institution, founded in 1603 to promote and cultivate natural science studies. It counted Galileo Galilei as a member, and it has never ceased to pursue its goal. Nowadays, it is an excellence cultural centre and is among the advisors of the President of the Republic.
I have put this post under the "psychology" category, although it discusses a chess game, for one important reason. Chess is a game, an art, a sport - you can categorize it in many different ways. However, what characterizes chess the most, in my opinion (an educated one, as I am an amateur with a long past of chess tournaments)  is the chance it gives to the players to mess up with each other's mind.
Wait, I can almost hear you say it: "Xi_b what? Let's move on, where's the sports section?" Ok, if you need to, please go. But do not underestimate excited Xi_b baryons. They are a helluva lot of fun to watch as they pop into existence and then decay in stages, as if stripping piece by piece, throwing out opaque layers of matter one by one, and finally exposing their naked beauty in full bloom.

Are you getting aroused yet? we are talking about a haDR-on here, don't be mistaken, but the matter is not less sexy than the stuff you'd get on the sports section anyway. For, you know, there is simply so much we still do not know about how quarks can create excited states of nuclear matter, that one cannot ignore any new development. 
[This is the second part of a two-part article on Cosmic Messenger astrophysics. For part 1, please click here.]

We can also "see" showers of secondary particles from cosmic rays thanks to the Cherenkov light they produce. Cherenkov light is emitted when charged particles travel in a medium at speeds higher than the speed of light itself! Light, in fact, slows down a little when it traverses a medium; energetic particles do not, so they create a conic "shock wave" similar to the boom of supersonic airplanes. 

Have you ever looked up to a clear sky on a moonless night, in a place away from large cities? If you have, you will remember seeing hundreds of bright stars, and maybe even the faint collective glow of 250 billion more within the Milky Way, our own galaxy.