Physics

It happens in the best families, so they say. Two experiments work 24/7 to produce an improved result on the Higgs search, and the result is disappointing, to say the least.

I am talking about the Tevatron, of course. For a little while longer, CDF and D0 will have the exclusive on Higgs boson searches. Last March, we all rejoyced when we saw that the Tevatron was starting to become sensitive to a high-mass Higgs, and indeed it excluded its existence in a range of masses between 160 and 170 GeV. We were waiting for more exclusions for the winter conferences of 2010, when more data would be used to produce improved results. Instead, no improvement, but actually, a retractatio. How is that possible ??

I recently discussed here the Tevatron results of searches for new Z bosons in electron-positron or dimuon samples collected by CDF and DZERO, pointing out that there seem to be a couple of intriguing upward fluctuations in the data. One of the dielectron fluctuations sits at a mass of 240 GeV, the other, also in the dielectron spectrum, is at about 720 GeV. Neither is compelling.
Today CNN features a short video with an interview to Professor Nielsen, the mastermind behind the whole "Higgs comes back from the future to prevent its own creation" crap.  I wrote about the matter a couple of times in the past, and will not reiterate here that I think his suggestions to pull out cards from a deck to decide whether to carry on basic research with the LHC is a unmitigated pile of you know what.
What is the most important object physicists manipulate everyday?

My answer with no hesitation is : the Lagrangian !

What is it? simply the object that contain everything one need to know about a given physical system.
Last May the CDF collaboration published their observation of the  baryon, a particle made by a very exotic "bss" quark triplet. The CDF result came almost one year after a similar measurement was published by the competitor experiment, D0.
Today I got access to a collection of very cool pictures of the CMS detector, one of the two experiments designed and built to study proton-proton collisions delivered by the Large Hadron Collider at CERN.

Many of those pictures, which were taken by Michael Hoch (CERN/CMS) in the last couple of years, have circulated in the web for a long time, and individual ones have been used in several places. However, they are very nice to browse one after the other. And I think they are even more interesting to watch if one has not had the privilege of visiting the giant detector in its underground cavern, during its assembly last year. So I take the liberty of showing them to you here, in case you missed them - or just like to refresh your memory on this technological marvel.
Newtonian mechanics has marked the beginning of a new era for physics. Indeed the newtonian formulation of the gravitational force has allowed to prove the heliocentric theory developped by Copernicus and defended by Galileo. It is a very interesting story that deserve a full post (maybe one day, if I have enough time...).
Today, having little inspiration to write anything original myself, I decided to have a look at what other sites held by colleagues or friends are dealing with. I offer below a few interesting links, with minimal commentary.

  • Peter Woit is always more informed than anybody else, with more precise data available earlier than anywhere else, on the status of the LHC project. I advise you to keep an eye on his blog in the near future.
A good part of basic research in fundamental physics focuses on the definition, the prediction, and the measurement of quantities which put the current theory -the standard model- to the test in the most stringent way possible. The choice of the quantities on which to base our comparisons between theory prediction and measurement is critical: it entails understanding what may make the comparison imprecise (i.e. experimental systematics affecting the measurement) or fruitless (i.e. theoretical assumptions or a bad definition of the quantity to measure).

One clear example, which I used last week in my lessons of Subnuclear Physics to undergraduates in Padova, is the measurement of the W and Z boson cross sections at the Tevatron proton-antiproton collider.
Measurements matter in global climate affairs. "IBUKI" is the Greenhouse gases Observing SATellite (GOSAT) that has been circling the Earth since January 23, 2009.  

IBUKI ('breath' in Japanese) will assist in precise monitoring of the global atmospheric carbon dioxide concentrations when its observation data sent from space are combined with data obtained on land and used with simulation models. Methane is also observed.

Onboard Instruments