Physics

"The senior signs the paper, the post-doc thinks, and the grad student executes" F.S., explaining how the typical nucleus of analysis group in HEP works.

Want to boil water in less than a trillionth of a second? Now you can, if you are at the Hamburg Center for Free-Electron Laser Science and can find someone to build your theoretical concept. Still, heating water 600 degrees Celsius in just half a picosecond seems like a fun application. If it ever does get built, it will be the fastest water-heating method on earth.   All it takes for superfast water heating is a concentrated flash of terahertz radiation - well, theoretically. Terahertz radiation consists of electromagnetic waves with a frequency between radio waves and…

In 1989 the CDF experiment was sitting on its first precious bounty of proton-antiproton collisions, delivered by the Tevatron collider at the unprecedented energy of 1.8 TeV. One of the first measurements that was produced was the measurement of the mass of the Z boson, which was at the time known with scarce precision by the analysis of a handful of candidates produced by the CERN SppS collider, at a third of the Tevatron energy.  Additional motivation to perform a precise measurement of the Z boson mass was the competition with the Mark II experiment at SLAC. In those years there was…

It could be in a billion years, it could start tomorrow, but physicists have long predicted that the universe may one day collapse, and that everything in it will be compressed to a small hard ball. Like a lot of things, it just takes a little mathematics to conclude that the risk of a collapse is even greater than previously thought. Sooner or later a radical shift in the forces of the universe will cause every little particle in it to become extremely heavy. Everything - every grain of sand on Earth, every planet in the solar system and every galaxy – will become millions of billions…

No, this is not an article about top models. Rather, the subject of discussion are models that predict the existence of heavy partners of the top quark. Ever since quarks were understood to be the constituents of hadronic matter - protons, neutrons, and every other composite object held together by the strong force - the search for new such elementary objects has enthralled particle physicists. Experimentalists have tried to produce heavier copies of the six known quarks (respectively called up, down, charm, strange, top, and bottom) using higher and higher collision energies; theorists have…

"During the years 1962 to 1964 a debate developed about whether the Goldstone theorem could be evaded. Anderson pointed out that in a superconductor the Goldstone mode becomes a massive plasmon mode due to its electromagnetic interaction, and that this mode is just the longitudinal partner of transversely polarized electromagnetic modes, which also are massive (the Meissner effect!). Ths was the first description of what has become known as the Higgs mechanism.Anderson remarked that "the Goldstone zero-mass difficulty is not a serious one, because we can probably cancel it off against an…

Inspired by my friend Peter Woit's openness in discussing his work in progress (a thick textbook on the foundations of quantum mechanics), I feel compelled to come out here about my own project. I have been writing a book on the history of the CDF experiment and the anomalies that we unearthed (and sometimes re-buried) in the course of thirty exciting and eventful years. The book is aimed at laypersons, and the level of the discussion of the physics is not different to the one within which I usually stay when I write about physics in this blog. Also, since I am well aware that reading…

I'm speaking of bare particles. "Heroes" is maybe too pathetic, but blocks or "bricks" would be OK since everything is made of them despite their being non-observable. Why are they non-observable? Because they are non-interacting particles or particles "before interaction". Inaccessible, for short. Let us take QED - the first QFT Nobel prises were given for. Its Lagrangian is the following: It is relativistic and gauge-invariant because the bare electrons, positrons, and photons are such. Parameters  and are bare electron mass and charge and the term  is how bare particles…

Just a quick link to allow you to browse a very nice set of pictures taken at CERN by Andri Pol. The subjects are physicists in their daily activities - brainstorming at the blackboard, cycling around the lab, bitching about the mess in the common coffee room, or working at various pieces of hardware:you can see them here. Enjoy!

Last Tuesday I was in Mantova, a pleasant little town in northern Italy, rich of monuments and treasures like the Palazzo Ducale,  which hosts a vast collection of paintings and frescoes from reinassance artists. But I was not there for a private visit; I was in fact invited to comment and provide answers to questions that the audience of a movie, "The Hunt for the Higgs", were invited to ask after seeing it. The host of the event was the "Cinema del Carbone", a small movie theater near the center of the town. The organizers called me there because they knew me from my previous…