Physics

A long awaited confirmation that direct CP violation occurs in Bs mesons (particles composed of a b- and an s-quark) not unlike what happens to lighter mesons (the K0, the B0, and the D0) is coming from LHCb. In an article appeared yesterday in the Cornell arxiv, LHCb describe their measurement of direct CP violation in the decays of both B0 and Bs mesons to Kπ final states (a kaon and a pion). The former is now the best precision measurement we have of the phenomenon, the latter is also the most precise bid (only one former measurement of the effect exists). The LHCb experiment operates at…

[Title correction: My goal was to create images of 2D, 3D, and 4D functionals. I think I missed that target. Instead I have 1D parameterized curves that all move in up to 3D in space + time. I have a clear idea how to write new code that could move independently with two, three, or four parameters. That code is not written now, so I will change the title to more accurately reflect the content.]Nothing like writing a title where I am not sure if I can pull it off. It reminds me of skiing slowly off a 6 foot cliff in Colorado. By the time I landed, I was going fast. Nothing like the constant…

Thanks to Sven Heinemeyer and his colleagues, we can give a peek today at the status of the agreement of top and W boson masses with Standard Model predictions for the Higgs boson mass, and with SUSY predictions as well. The figure below is just one of the many versions he has produced. Maybe I should not say "SUSY predictions", as it is clear, by inspecting the figure above, that the green band is quite wide, a result of the many free parameters whose value have an impact in determining the mass of the lightest Higgs scalar. In any case, the graph represents an impressive picture of self-…

The Tevatron collider has been shut down for almost half a year now, but the CDF experiment is still busy producing world-class measurements of fundamental Standard Model parameters. Actually, the above is not quite correct: CDF is re-defining "world class" in some cases. The measurement I am going to describe, which has just been made public (if you are quick you can follow live the seminar presented by Prof. Ashutosh Kotwal at Fermilab here), totally outperforms all previous determinations of a crucial ingredient of the Standard Model: the W boson mass. Before the new CDF result, we knew…

Do you accept science as far as has been experimentally verified? Are you a modern agnostic knowledgeable about the difference between pseudo-science and the proper stuff? Yes? Good, I was looking for you. Allow me to ask you a question. Well, let me first prepare the background a little, but trust me, I will only ask you one question, namely “Do you honestly believe that?” Quantum mechanics has been proven valid to an absolutely astounding accuracy totally unusual for theories generally. Quantum physics seems to be the only theory that is not just linear in its early stages. All subfields…

This just in: the controversial Opera result on superluminal neutrinos is affected by a previously unaccounted for experimental error, which completely overturns the conclusions. This is explained in detail here. Note that the source is James Gillies, head of Communications at CERN, and thus hardly a "unofficial leak". In fact, tomorrow there will be a CERN press release on the matter. The relevant quote is the following: "earlier this month scientists found a problem in the GPS system used to time the arrival of neutrino particles at an underground lab in Italy. Gillies says only further…

About a month ago I held a three-hour course on "Statistics for Data Analysis in High-Energy Physics" in the nice setting of Engelberg, a mountain location just south of Zurich. Putting together the 130 slides of that seminar was a lot of work and not little fun; in the process I was able to collect some "simple" explanatory cases of the application of statistical methods and related issues. A couple of examples of this output is given in a post on the fractional charge of quarks and in an article on the weighted average of correlated results. But there is more material to be dug out. Among…

Sophisticated physicists appreciate the dance of abstract symbols. I need to build something. The abstract is more real when made out of clay and pipe cleaners. In this blog on the 1D Euler Lagrange equations, beads (not clay) and pipe cleaners will be used to appreciate this important tool, followed by the same story told with symbols. [note: I missed my usual self-imposed deadline because I was not able to get the icon bar to appear in Google Chrome on a Mac. The browser Opera worked, so long as I cut and plasted URLs for images and HTML code from codecogs.] Calculus is the study of change…

February 23rd 1987 is a day indelibly imprinted on the minds of everyone interested in astrophysics. At 7:36 GMT that day, now 25 years ago, the big one hit us. There was no escape. For 13 seconds a tsunami of neutrinos, emanating from a giant star eleven billion times more distant than the sun, flooded earth. This wave of neutrinos paled the steady stream of neutrinos reaching us from the sun by a factor of more than ten thousand. Yet no one noticed. That is, until Masatoshi Koshiba and his team inspected the data from their Kamiokande II neutrino telescope. Soon it became clear…

A nice new search for heavy quarks has been completed by the ATLAS collaboration in 7 TeV proton-proton collisions data collected in 2011. The ideas behind the search are instructive to describe, so I will spend some time trying to do that before I discuss the results and their meaning. Quarks: properties and decaysAccording to the Standard Model of particle physics, matter at the subnuclear level takes two forms: quarks and leptons. What distinguishes these particles is that the former, in addition to an electric and a weak charge, carry units of an additional quantum number called colour…