ATLAS has just produced a very nice new study of jet production in Z-boson events. I will describe a sample graph below, but before I do I find it useful to explain to the less knowledgeable among you what a hadronic jet is, just in case you've been away during the last forty years.
Hadronic Jets: what are they ?
One of the most intriguing effects in subatomic physics is the phenomenon of violation of the discrete symmetry called "CP". It is intriguing at various levels.
First of all, CP violation is intriguing because of the depth of the concept: proof of that be that it is not at all easy to explain it to outsiders (I will make an attempt below, but I am likely to fail!).
Second, its elusive nature makes it even more mysterious and difficult to study: only a few subatomic physical systems exhibit it, and the effect is visible only as a modification of measurable quantities at the level of a few parts in a thousand.
In quantum physics, objects can be in more than one place at a time and future events can change the past - don't get caught up too much in that or you won't sleep at night.
A new paper says quantum physics can be even spookier. Using the “chained” quantum Zeno effect, the researchers write that they have discovered a form of "almost psychic communication" in which information can be exchanged between two parties without photons, or any physical particles, traveling between them.
Here are my big picture house rules: no equations in LaTeX or Mathematica. Graphics are allowed so long as they are done by hand. Visually, images break up the monotony of text and provide convenient landmarks. Numbers will be used so long as they are made up, are easy to work with, and are somewhat related to the problem.
Cryogenic Dark Matter Search (CDMS) collaborators are reporting what could be a weakly interacting massive particle (WIMP) signal at the 3-sigma level.
In common parlance, that is 99.7 confidence - which sounds high. But to physicists it really means they have 3 bumps in their data that could be a WIMP, which means it might be a hint of dark matter.
That sounds like a lot of qualifiers but particle physics is conservative that way. Data means what it means and not much more. But certainly not less, and that is pretty important too.
Pictures showing the structure of matter and the organization of subatomic particles in different categories abound. Indeed, cataloging and classifying entities subject of study is a powerful means of grasping their essence and infer their properties. The most striking example I can offer is the Mendeleev table of elements (which allowed its creator to spectacularly deduce the existence of elements not yet discovered); but there are many others, like the Hertzsprung-Russell diagram of star classification, or the one for galaxies, or the cataloging of animal species...
Probably no signs of gravitational waves, signs of dark matter but not a discovery. That is the word from this first day of the American Physical Society's meeting in Denver Colorado.
In the plenary keynote session of the meeting today, I asked a question of Lloyd Knox of the PLANCK collaboration. My question regarded the B mode polarization data and what it may show. He said that this data would be officially released next year. He also expressed the professional opinion that the data may not show a strong gravitational wave signal. This would be significant since the simplest models of inflation predict a strong gravitational wave signal. Dr. Knox went as far as to state “the simplest models are probably ruled out” (not quite verbatim.)
Results from Planck and AMS-02, but also the way they are often presented, have created a very exciting situation. Its exceptional character has led me to quickly write an article, Planck data, spinorial space-time and asymptotic Universe, and to make it public for open discussion.
"What are the radiation doses to airplane passengers from the intense bursts of gamma-rays that originate from thunderclouds?" researchers asked at a press conference during the European Geosciences Union in Vienna today.
There have been other attempts in the past, so this is not strictly a new idea. However I found the interactive web page at http://htwins.net/scale2/
extremely well constructed.
It is a graphical display of the largest and smallest structures from galaxy superclusters down to quarks and the Planck length. By moving a scroll bar left or right, you can get a very clear sense of scale of the different things. And in so doing you learn the relative size of different objects, from planets to stars, or from stars to galaxies; or vice-versa, from cells to molecules and atoms.
I highly recommend it!