# Guess The Plot 3 - and a tribute

May 24 2011 | comment(s)

Upon being reminded by an automated messaging system, somewhat disturbingly, that today would be the birthday of an esteemed colleague -were he not dead- I decided to post a "guess the plot" entry which pays him a tribute.

The figure below is for you to guess (ignore the blue box at the lower right -it just hides some giveaway information). What does it represent ? What is in the abscissa ? And on the y axis ? Why do the data only populate the upper left half ? And what causes those two funny concentrations ?

# Argand Plane Crash

May 23 2011 | comment(s)

The complex plane should be known as the Wessel plane, after the Norwegian-Danish land surveyor. His paper of 1799 was ignored because few were reading the preprint server at that time. Mr. Bookshop in the big city of Paris gets his name associated with graphing complex numbers in a plane. This is one reason I avoid naming things for people as proper credit is complicated.

# CMS Sees Hint Of Upsilon Suppression In Quark-Gluon Plasma!

May 23 2011 | comment(s)

A few months ago LHC took a special run of proton-proton collisions at  2.76 TeV. Why the lower energy, now that we are accustomed to searching for new phenomena at the highest available energy of 7 TeV ? Because of the wish to compare lead-lead collisions, taken last year at 2.76 TeV nucleon-nucleon energy, with proton-proton ones. The comparison allows to extract extremely interesting results.

# LHC Reaches 10^33 Luminosity!

May 23 2011 | comment(s)

Just a short post to mention that the Large Hadron Collider has reached tonight the top instantaneous luminosity of 1.075 * 10^33 cm^-2 s^-1. This is a new record for high-energy hadron colliders, improving over precedent records already set this year by the CERN machine. The peak luminosity is 2.5 times larger than the highest reached at the Tevatron (which, one needs to remember, collides protons against antiprotons, and the difficulty in producing the latter makes the comparison between LHC and Tevatron luminosity a bit deceiving).

# The Plot Of The Week - Same-Sign Dileptons

May 22 2011 | comment(s)

The plot of the week is actually a table this week. A histogram with several background components can be extremely informative, but sometimes a table provides more detail and one can focus better on interesting features.

The table below has been produced in a CDF search for events containing same-sign lepton pairs: a striking signature of new physics, faked by very few processes. Because of the paucity of Standard Model sources, even relatively small new physics signals can emerge in such a sample. The CDF analysis is based on 6.1 inverse femtobarns of proton-antiproton collisions collected at the Tevatron during Run II. Let us see what the table tells us.

# To Be Is To Be Measured (Part 1)

May 21 2011 | comment(s)

Quantum mechanics allows us to perform the following experiment (see the article by David Mermin in Physics Today Vol. 38 No. 4):

# Disproving Local Realism

May 21 2011 | comment(s)

Modern physics has disproved direct realism: There is no locally realistic description of our world possible. Although I have already explained this differently at several places, for example by refusing 'real stuff' as being a good explanation for what is ‘at the bottom’, it is worth to prove it once rigorously. Let me present the simplest established proof in the simplest possible version that I can come up with. Everybody claiming interest in the interplay between science and philosophy should have gone through this proof at least once and I did my utmost to make it as easy as possible: Only three angles are considered and probabilities almost completely avoided by instead talking about natural numbers like 50.

# On Narrow Bumps

May 18 2011 | comment(s)

A question posed by Tony Smith in the thread of the previous post (which dealt with the choice of the bin width in histograms) triggered me to do a little work to produce a convincing answer to him.

The issue is the following. Tony got interested in a few top candidate events in a few mass distributions published by CDF and DZERO quite some time ago, which seemed to all cluster in the surroundings of 145 GeV. Could those eight candidate events (once summed across the various channels and experiments) be the signal of some resonance different from top quarks ?