Physics

For decades, physicists have searched for exotic bound states comprising more than three quarks.

In 2011, over 120 scientists from eight countries discovered strong indications for the existence of an exotic dibaryon made up of six quarks. Now, experiments performed at Jülich's accelerator COSY have shown that uch complex particles do exist in nature. This discovery by the WASA-at-COSY collaboration goes beyond what had been done before. Physicists were only able to reliably verify two different classes of hadrons: volatile mesons comprising one quark and one antiquark and baryons consisting of three quarks.


Space seems like an empty box that lives through time. This can already be classified as a “better model”, as you can see in the table below. However, this tacitly held model makes people wonder: If I toss a coin and find myself with the result being “tails”, where is the other me, the one who found “heads”, the other possibility which physics can no longer ignore, and which good philosophy has always known to be equivalent?

Has a universe popped up next door to this one?

If you’re flying in the vicinity of a black hole, seatbelts and a bumpy ride are really the least of your concerns, but we are in the world of the hypothetical, and the accepted wisdom among gravitational thinkers has been that spacetime cannot become turbulent. 

An idea by the wizards at the Perimeter Institute is that such accepted hypothetical wisdom might be wrong.

The researchers followed this line of thought: Gravity might be able to behave as a fluid. One of the characteristic behaviors of fluids is turbulence – under certain conditions, fluids don’t move smoothly, they eddy and swirl. 

Presto, let's put something on arXiv.


You are the first to arrive to a dinner party and must choose the table where to sit, relying on your past experience of how handsome members of the opposite sex (you're straight) usually choose their seat. You need to buy stocks based on past performances and trends. You travel to some distant location and would like to know what's the weather like there, but there is no forecast for that particular place. What do you do ?

Observations with the 1.6-meter telescope at Big Bear Solar Observatory (BBSO) in California, the most powerful ground-based instrument dedicated to studying the Sun, have resulted in the highest- resolution solar observations ever made.


They key issues in the discussion of the BICEP2 result center around the way BICEP2 accounted for dust in the foreground.  They based their analysis on a presentation graphic which was shown at the April APS conference of 2013.  This may have been a mistake.  In the defense of the BICEP2 team, that graphic was the best data available at the time.  A .fits file of this particular data from PLANCK did not exist yet. Never the less, it leads to reasonable questions about the validity of the result.
"After the 1974 London Conference, with its strong confirmation of the quark model, a general change of view developed with regard to the structure of hadrons. [...] the quark structure of hadrons became the dominant view for developing theory and planning experiments. A crucial element of this change was the general acceptance of QCD, which eliminated the last paradox, namely, why are there no free quarks ? The conjectured infrared slavery mechanism of QCD provided a reason to accept quarks as physical constituents without demanding the existence of free quarks. The asymptotic freedom property of QCD also provided a ready explanation of scaling [...].
One of the nice details lost in the big picture of the Higgs boson discovery of 2012 is that a significant part of the signal put in evidence by ATLAS and CMS is produced by a very special kind of interactions between the protons accelerated by the LHC. These are "vector boson fusion" processes, whereby it is not the protons or its constituents that come in direct contact, but rather, each proton emits a W boson, and it is the latter pair which fuse together, give rise to a Higgs particle.
I reported here a few days ago about a very nice challenge issued by the ATLAS experiment: find Higgs boson decays to tau lepton pairs in a sample containing signal as well as background events, using a training sample with correct signal and background labels per each event.

The challenge consists of solving a typical classification problem in a highly multidimensional space (30 dimensions) better than all other participants - the metric to judge being an "approximate median significance" of the subset of events that the user classifies as "signal". This is given by the formula

AMS = sqrt {2 * [(s+b+10) * log(1 + s/(b+10)) - s] }
I am spending the week in the pleasant resort of La Biodola, in the Elba island. Elba is a beautiful island just off the coast of Tuscany. Here Napoleon was exiled after his abdication in 1814 (he arrived here on May 30th). Exactly 200 years later, 100 Italian researchers have decided to exile themselves here to discuss the future 10 years of accelerator-based experiments, to understand where to "put their money", or better their research activities and efforts.