Physics

Besides the usual share of random readers who google something and get directed here by mere chance (to be read: by the sheer amount of valuable information I have posted here), this blog is read by an interesting mix of particle physicists, students, experts in other fields of Physics, and Science amateurs -plus a small number of science reporters looking for news. Of course I love each and every one of my faithful readers like good teachers love their pupils, but among the varied crowd, the readers which I am most happy to host here are students and amateurs, because they provide me with…

Time for a quick compare-and-contrast. Here is what "Physics Today" lists as their top stories and most popular articles for July 2009: Farewell to the bevatron Earliest astrophysical object yet seen House narrowly passes climate change bill Miller to run nuclear division at DoE Industrial R&D in transition Need for clean energy, waste transmutation revives interest in hybrid fusion–fission reactor Probing stars with optical and near-IR interferometry Rogue waves Guessing that the equivalence to 'top stories' and 'most popular' is our ScientificBlogging.com 'most recent' and 'most…

Scientists at Penn State University, in collaboration with institutes in the US, Finland, Germany and the UK, have figured out the long-sought structure of a layer of C60 – carbon buckyballs – on a silver surface.  The results in Physical Review Letters and Physics  could help in the design of carbon nanostructure-based electronics. Ever since the 1985 discovery of C60, this molecule, with its perfect geodesic dome shape has fascinated scientists, physicists, and chemists alike. Like a soccer ball, the molecule consists of 20 carbon hexagons and 12 carbon pentagons. The electronic…

One year ago, a paper by a distinguished group of theorists announced first evidence of new physics from measurements of the properties of B_s mesons performed at the Tevatron by the CDF and DZERO experiments. They had combined all the available information, obtaining a result which disagreed with the Standard Model (SM) prediction by more than three standard deviations. The study was quickly criticized because of some of its inputs: the unavailability of some information on the Likelihood function used by DZERO in their experimental results was not a fault of the authors, but was enough to…

An article in the latest (August 2009) edition of Scientific American describes an astronaut floating motionless with respect to his distant spaceship. He is not tethered to the spaceship and has no objects available that can be hurled away or can in some other way create a thrust. How is he ever going to make it back to his spaceship? His situation seems hopeless. However, he remembers the lessons he received as rookie astronaut on swimming in empty space. By applying a weird degenerative form of breaststroke the astronaut slowly moves toward the spaceship and makes it safely back before he…

A new paper on the ArXiV caught my attention this evening for several reasons. First of all, because two of its five authors (J.Ellis, J.R.Espinosa, G.F.Giudice, A.Hoecker, and A.Riotto) are (or have been) my colleagues in Padova University; second, because the title is quite catchy; third, because indeed the results it presents are valuable food for thought. The paper is titled "The Probable Fate of the Standard Model". Here, contrarily to what is fashionable nowadays, rather than predicting the demise of the Standard Model because of the discovery of this or that brand of new physics…

"Other people's data ntuples are a bit like their genitals. You may occasionally be allowed to play with them, but you should not expect to be granted unhindered access."Unknown (the previous attribution to M. F. is fallacious)

In Toledo, Ohio on June 26, 1914 -- a star was born. He was named Lyman Strong Spitzer, Jr. for good measure. An asteroid, a space telescope, and a building in the Princeton Plasma Physics Laboratory (PPPL) bear his name today. His theoretical and applied research contributions shaped three fields of science, namely, interstellar matter, the dynamics of star clusters, and the physics of plasmas. Professor Spitzer conceived in 1951 the "stellarator" for magnetic confinement of a plasma in a twisted-tube configuration. The Princeton Plasma…

In this two-parts article I wish to describe in some detail, but still at an elementary level, the characteristics of one of the most important probes of the physics of subnuclear collisions at today's particle physics experiments: jets of hadrons originated from energetic bottom quarks, or more familiarly, b-jets. By posting a dedicated article on b-jets, I hope I will be able to describe in more detail elsewhere other physics topics, such as Higgs boson decays or top quark signatures, without being hampered by having to introduce the phenomenology and detection of b-jets from scratch every…

As silly as it may look, I am going to start this post by publishing for the third time in a row the same figure. That is because I want to keep the promise I made earlier that I would explain in terms as simple as possible (although not simpler) the details hidden behind the coloured curves and functions pictured there. I will also take this chance to come down a little from the level of technicality of the recent posts: after all, this blog is supposedly for everybody, and not just for Ph.D. students and recipients. The figure above, a few of whose "secrets" I wish to unveil in the…