In a few days, scores of Italian post-doctoral researchers in experimental particle physics will get tested on their knowledge of the matter, without any promise of a position, but just to get one further "stamp" on their curriculum, testifying that they are competent enough to be worth offering a temporary position by INFN, the Italian Institute for (sub)Nuclear Physics. So this is a  national exam, with the sole purpose of giving a green light to be admitted to two-year positions , which are typically paid less than 1400 euros a month, and which are so far not available. Frankly, I feel ashamed, since I myself work for INFN, and I strongly disagree with its current recruitment policies.

From Prof. Chad Orzel's Graduation Speech:

Science isn't a body of facts, science is a process for figuring out how the world works: you see something interesting, come up with an idea of why that might happen, and test you're idea to see if you're right. You repeat this process until you figure out why things happen the way they do, and then you use that knowledge to explain new things, or to do things that you couldn't do before.

If you have followed this blog for long enough, dear readers, the words "multi-muons", "anomalous muons", or even "lepton jets" are not foreign to you. They all refer to a paper appeared on the ArXiv on the evening of Halloween last year. In the paper the CDF collaboration published the results of a detailed analysis which described how a component of collider data containing two or more muons could not be explained by known Standard Model processes.

In a few days italian post-docs working in high-energy physics will be asked to gather for a nasty exam, held by the INFN -the italian institute for nuclear physics- to qualify valiant researchers for future hiring in the institute.

The exam generated a wave of outrage among the very pool of people at which it is aimed: the scores of "precari" (temporary workers) who are spending the best years of their life to try and make a career in particle physics.  Let me explain why that is so.

Prologue

For a long time, recreational computer users all over the world have benefitted from improvements to computing systems that were invented in order to facilitate research in fundamental physics. The foremost example is, of course, the World Wide Web which you are using to read this.

Now the time has come for the gamers to give back to physics. Of course, nobody would buy that as a moral argument, but money talks louder than most ethicists, and the market for games consoles and graphics cards has become huge and strongly driven by increases in computational performance, leading to ever faster graphics processors being developed to please the gamers. If you have a moderately recent desktop computer, odds are that the graphics card has more computational power than the CPU.

Below I offer a preview of the slides I will show tomorrow at an invited seminar on the rather technical topic of  "The b-jet energy calibration with Z-->bb decays", which I have come to CERN to give at a meeting of the LHCb collaboration. As I mentioned already in the first part of this two-part article, the topic is rather technical, and I do not expect a large audience -but I will nonetheless make an attempt at explaining the meaning of the slides pasted below. Then, of course, I am available to provide some additional light on any specific issue among those dealt below which you may want to understand more about.

Tomorrow I am traveling to CERN, where I have been invited to give a seminar at a meeting of the LHCb experiment. My talk will discuss the issue of the energy calibration of b-quark jets, a topic to which I have devoted a good part of my research time for the last thirteen years. The talk will of course be centred on the explanation of the analysis Julien Donini and I, together with a few colleagues, performed in CDF a few years ago, the search for Z boson decays to b-quark jet pairs.

Created in a Bose Einstein Condensate, sound may enter these acoustic black holes but it may not leave.  This creates an system we can experiment with on a table top level and learn about black holes from it.  

The strange and unique features of the Bose condensate never cease to surprise us.  A while back they were used to slow a beam of light almost to a standstill. Now a research team out of the institute of technology in Haifa Israel claims to have created "A sonic black hole in a density-inverted Bose-Einstein condensate." by O. Lahav, A. Itah, A. Blumkin, C. Gordon, and J. Steinhauer (Arxiv link to PDF). 

The folks at In the Dark have come up with A Unified Quantum Theory of Sexual Interaction.  This is the best geek hilarity I've ever seen.  It's probably even funnier if you have any idea what they are talking about, in regard to quantum theory.  I particularly enjoyed their quip about string theorists "twiddling their thumbs":

Self- interactions involving a solitary phase are generally difficult
to observe,  although examples have been documented that involve
short-lived but highly-excited states  accompanied by various forms of stimulated emission,

The search for planets capable of sustainable life (as we know it) is on, but with an infinite number of planets astronomers are focusing their attention on each system's 'habitable zone', where heat radiated from the star is just right to keep a planet's water in liquid form.

They have found planets orbiting red dwarf stars because those make up about three-quarters of the stars close to our solar system. Potentially habitable planets must orbit closer to those stars, perhaps one-fiftieth the distance of Earth to the sun, since they are smaller and generate less heat than our sun.

It is a well-known fact that it is much easier to measure a physical quantity than to correctly assess the magnitude of the uncertainty on the measurement: the uncertainty is everything!

A trivial demonstration of the above fact is the following. Consider you are measuring the mass of the top quark (why, I know you do it at least once a week, just to keep mentally fit). You could say you have no idea whatsoever of what the top mass is, but you are capable of guessing, and your best guess is that the top mass is  twice the mass of the W boson: after all, you have read somewhere that the top quark decays into a W boson plus other stuff, so a good first-order estimate is 2x80.4= 160.8 GeV.

Core-collapse (or gravitational) supernovae are among the most energetic and violent events in the universe and  constitute the final tremendous explosions in the life cycles of stars 8 times more massive than our Sun.

After running out of fuel, the core of such a star collapses and forms a neutron star or a black hole. At the same time, the outer layers are ejected at high velocity (up to 10% of the speed of light) and shine as brightly as billions of stars together.

To provide some perspective, the total energy suddenly released by such a supernova exceeds the total energy release by our Sun to-date; and also in the next 10 billion years.

It feels good, for a die-hard sceptic like I am, to live and let unexplained phenomena die. The phenomena in question are measured deviations from the predictions of the Standard Model (SM), our wonderful theory of subnuclear interactions, which has been condemned to fail by theorists soon after its construction, but continues, disappointingly for many, to succeed in explaining experimental results.

'True muonium' is a long-theorized but never-seen tiny atom that was first proposed more than 50 years ago.  True muonium, which unlike "muonium" (an atom made of an electron and an anti-muon) is made of a muon and an anti-muon.   Both muons and anti-muons are created frequently in nature when energetic particles from space — cosmic rays — strike the Earth's atmosphere yet their existence is fleeting and their combination, 'true muonium,' decays naturally into other particles in a few trillionths of a second. This has made observation impossible.

But it might be observed even in current collider experiments, according to theoretical work published recently by researchers at the SLAC National Accelerator Laboratory and Arizona State University.

This is going to be a rather long piece, so for the lazy and the absent-minded among you I decided to put together an executive summary at the top, and not at the bottom of the article as I usually do. It is a bit of a spoiler, but those of you who can invest some time reading about particle physics will not be deterred by the first few lines of text. Besides, an executive summary is needed because we are discussing real news here: so here it is.

The "new" section of experimental physics papers in the arxiv today features a preprint by the CDF collaboration, titled "First Observation of Vector Boson Pairs in a Hadronic Final State at the Tevatron Collider". This is another instance of a difficult analysis where the CDF and DZERO experiments have competed in the past, and one which is relevant for Higgs boson searches. And CDF got there first once again.

I will describe in detail the analysis and the results later today, because this particular study is dear to me for at least three different reasons:

This afternoon Lisa Randall, one of the most famous theoretical physicists of our time, received from the hands of Flavio Zanonato, mayor of Padova, the keys of the city.

This morning the Planck 09 conference started at the Auditorium Altinate (see picture, right) in Padova. For a week, theorists and experimentalists will discuss hot topics in a variety of fields, from particle physics to cosmology, to string theory. A PDF file with the program is online.

When Albert Einstein constructed his general theory of relativity he decided to resort to some reverse engineering and introduced a 'pressure' term in his equations. The value of this pressure was chosen such that it kept the general relativistic description of the universe stable against the gravitational attraction of the matter filling the universe.