Physics

   Astrophysicists have been looking for Dark Matter, something invisible but gives extra mass to galaxies since Fritz Zwicky measured the rotation of galaxies in 1930s. And looking for Dark Energy, something invisible in the space between galaxies that leads to gravity pushing those galaxies apart, since Adams Reiss and Saul Perimutter, accurate measured galaxies motions with supernova, in the late 1990s. But what astrophysicist rarely mention is that they have a problem much more visible and much closer to home. It is the Sun itself, and thus blindingly bright, but no less of a…

"Exact coverage, like the Grail of legend, if approached by any but a perfectlypure and holy frequentist, is borne away and vanishes from sight." Joel Heinrich, CDF internal Note 6438

Just as you thought it was over for 2011, and you proceeded to hung the Higgs mass plots on the christmas tree as a wish for stronger signals next year, ATLAS comes out with a new particle discovery. That's what I like of particle physics - there's always so much going on that the excitement is never really over. The new particle is not anything we doubted should exist: it is a bound state of a bottom and a anti-bottom quark just as others we have found in the past 34 years (starting with Lederman and collaborators' discovery of the Upsilon); however, it is the first time that this particular…

I was saddened today upon hearing of the death of Franco Rimondi, a colleague in the CDF experiment. Franco was a professor of physics at the university of Bologna since 1980. His research in particle physics encompasses the last forty years, during which he collaborated with many experiments, starting with bubble chamber kaon decay studies in the late sixties, and then ADONE at Frascati in the seventies, and the split field magnet (SFM) at CERN. The experiment he spent most of his research career on was however probably CDF, at the Fermilab Tevatron collider. I have known Franco since 1992,…

http://arxiv.org/abs/1112.5431  Search for Higgs bosons of the minimal supersymmetric standard model in p-pbar collisions at sqrt(s)=1.96 TeV "_We report results from searches for neutral Higgs bosons produced in p-pbar collisions recorded by the Dzero experiment at the Fermilab Tevatron Collider. We study the production of inclusive neutral Higgs boson in the tautau final state and in association with a b quark in the btautau and bbb final states. These results are combined to improve the sensitivity to the production of neutral Higgs bosons in the context of the minimal supersymmetric…

Have you ever looked at a histogram with the data displayed as counts per bin in the form of points with error bars, and wondered whether those fluctuations and departures from the underlying hypothesized model (usually overimposed as a continuous line or histogram) were really significant or worth ignoring ? The subject is one of the topics which takes the most time away in discussions which arise during talks at internal meetings of HEP experiments. Physicists in the audience will be always happy to compare their ability of eye-fitting and to argue about whether there's a bump here or a…

Have you ever looked at a histogram with the data displayed as counts per bin in the form of points with error bars, and wondered whether those fluctuations and departures from the underlying hypothesized model (usually overimposed as a continuous line or histogram) were really significant or worth ignoring ? The subject is one of the topics which takes the most time away in discussions which arise during talks at internal meetings of HEP experiments. Physicists in the audience will be always happy to compare their ability of eye-fitting and to argue about whether there's a bump here or a…

Every year since 1990, I have made a holiday card sending it to friends and family (a list of ~ 50). They have always been nerdy. I try and feature something about the physics I figured out in the year. This one is less upbeat than those in the past, but there is a reason for that ;-) Doug No math, no snarky puzzle. Next Monday/Tuesday, Dec 26, a vacation week.Monday/Tuesday, Jan. 2/3: Spinning the Interaction Story: Attracting and Repelling.

In the previous blog post we familiarized ourselves with a most remarkable device. A device resulting from 20th century science: Albert's chest of drawers. This chest, although presented as a gedanken gadget, is real in the sense that devices with the same characteristics have been built, although none of these take the actual shape of a chest of drawers. In fact, the devices built so far are way smaller in size. They are based not on drawers, but on photons or sub-microscopic particles. While scaled-down, their behavior is exactly like that displayed by Albert's chest of drawers. A behavior…

"[...] practically nobody took very seriously the CDF claim (not even mostmembers of the collaboration, and I know several of them), while practically everybody isnow convinced that the Higgs boson has been finally caught at CERN – no matter ifthe so called ‘statistical significance’ is more ore less the same in both cases" G. D'Agostini, "Probably a discovery", arxiv:1112.3620 Note: by using some sort of probability inversion, I will claim based on the above that according to Prof. D'Agostini, Prof. Matt Strassler is "practically nobody", since he is not convinced... ;-)