Possible tetraquark particles spotted at the LHC

Scientists at the LHC may have found another type of matter in the form of tetraquarks, or particles made of 4 quarks. If confirmed, this would be an important step in understanding how matter behaves at its most fundamental level. 

The paper on arXiv:  arXiv:1404.1903v1 [hep-ex]

Quark quartet opens fresh vista on matter

This could have a deep impact on our knowledge of the physical world: http://www.nature.com/news/quark-quartet-opens-fresh-vista-on-matter-1.13225.

ODE - It's a question of options

Recently, I have modeled - very summarily - a dampened spring driven by a given signal on one end and free on the other with Octave. The first results baffled me: when the signal was not starting at the beginning of my time range and when it returned to its original value under a certain time, the output would be completely flat, as shown in the following figure.

This is clearly wrong: there is no way that kind of signal won't result in a residual oscillations that will dampen over time. Interestingly enough, when the driving signal repeats, the output is different. But do you notice something weird?

Yup! The oscillations start only at the third descending edge: there is no way this can be the correct solution.

So where did it go wrong?

Let's change the start time for the driving oscillation.

When the first falling edge is at t=1, t=3 or t=5, the simulation shows no oscillation. When the first falling edge occurs at t=2 or t=4, the model seems to behave correctly, and when the first falling edge is at t=6, the first two falling edges are missed. This looks like the time step is variable, and if it falls on an "unchanging" output, it doesn't bother computing the intermediate values.

Octave's lsode_options() allows to get or set the options used by lsode(). These options include the tolerances, the integration method used, but also the minimum and maximum step size. By default the minimum is set to 0 (no minimum) and the maximum is set to -1 (no maximum): the step size can take any value and skip has many points as needed.

Here is the output from lsode_options() right after Octave was started.

Options for LSODE include:

  keyword                                             value
  -------                                             -----
  absolute tolerance                                  1.4901e-08
  relative tolerance                                  1.4901e-08
  integration method                                  stiff
  initial step size                                   -1
  maximum order                                       -1
  maximum step size                                   -1
  minimum step size                                   0
  step limit                                          100000

What if we change the maximum step size to be half of the pulse duration? Let's try that with the command lsode_options("maximum step size",0.5). The options are now

Options for LSODE include:

  keyword                                             value
  -------                                             -----
  absolute tolerance                                  1.4901e-08
  relative tolerance                                  1.4901e-08
  integration method                                  stiff
  initial step size                                   -1
  maximum order                                       -1
  maximum step size                                   0.5
  minimum step size                                   0

  step limit                                          100000

And my test set looks like this.

Which is way better: this is consistent with the spring oscillations starting at the first falling edge. Redoing the first example with the new options, I have:

And that  is consistent with the real life experience.

Peaceful matter-antimatte pairing looks more real

Interesting. This is the first time I read about the Majorana fermions, a very particular fermion which is also its own antiparticle. Scientists at University of Illinois at Urbana-Champaign are one step closer to showing these exists.

The article in the New Scientist.

Scientists Extend Einstein’s Relativity to the Universe’s First Moments

When one tries to apply Einstein's equations to very small spaces or times, the whole stuff breaks down and makes weird predictions. So, for the last decades, astrophysicists have been looking to unify Einstein's and quantum theories.

About 30 years ago, Ashtekar managed to do so and made Einstein's equation "quantum certified." A number of surprising results came out ... One of them is that the early universe was made of discrete cells that could assume multiple simultaneous states. Another prediction is that the Big Bang was rather a Big Bounce of a previous universe, that would have endured a Big Crunch!

The theory also predicts that there should be imprints. If found, it would confirm the Quantum Loop Theory, and possibly give other challenges to the astrophysicist: what was there before? How did the whole universal cycle started? Will it end?

Largest structure challenges Einstein's smooth cosmos

Slowes and his team have discovered a group of quasars that challenges Einstein's Large Scale Homogeneity Principle. This principle is simply the expression that, at large scales, the universe looks homogeneous.

However, going through the Sloan Digital Sky Survey, he and his team found a group of quasars that is above the limit generally admitted to be "large scale", meaning that in order to maintain the principle as valid, its lower limit has to be increased dramatically.  Which also means that Astrophysics just got a bit harder ;-)

Here is the link to the article in the New Scientist and the published paper on Arxiv.

California Meteor Broke Speed Record for Atmospheric Entry

That meteor would have got a huge ticket for its high speed upon entry.

Mathematical proof reveals magic of Ramanujan's genius

A cool article on the Indian mathematical genius Srinivasa Ramanujan. It seems some of his contributions could lead to a better understanding of black holes, a celestial body not even known during his time.

Astrophysicists spot the earliest galaxy yet

Very interesting: astrophysicists from the Hubble Team used the massive galaxy cluster MACSJ0647.7+7015 as a gravitational lens to detect a very early galaxy. This hit the jackpot and the team got a glimpse at the earliest galaxy yet, which appeared a mere 425 million years after the Big Bang.

You may find the official paper from the Hubble Team here.

zBox4 Construction: a supercomputer in 24 hours

What happens when you have a herd of turbonerds, 24 hours and the need to crunch lots of numbers? You get a cool video of a number crunching cluster being built!

The Institute for Theoretical Physics in Zurich needed an upgrade to the existing zBox cluster and the decision was taken to built the zBox4. Several details on the construction can be found here.


This monstrous beast is running Scientific Linux, a distribution oriented towards labs and universities and specially designed for clusters. With a theoretical value of 282 GFLOPS per CPU, this has a peak performance around 108 Teraflops, an impressive number that would be a candidate for the top500 list.

Bananas have gone nuclear!

So it seems that potassium-40 (⁴⁰K) is naturally occurring in bananas and that it can undergo a disintegration, emitting a positron in the process. This positron can then interact with an electron, emitting 2 photons around 511 keV, in the gamma ray portion of the EM spectrum. This is of course assuming that the pair electron-positron have a low kinetic energy.

As said, bananas have gone nuclear!