Tetraquarks are hypothetical particles made up by four quarks (two quarks and two antiquarks). Unlike mesons (quark-antiquark pairs) and baryons (three-quark or three-antiquark systems), the quarks in a tetraquark are quite loosely bound within their confinement volume by strong interactions, as can be calculated with the help of quantum chromodynamics. Their tendence to separate into two quark-antiquark systems should yield a very short lifetime, making their observation quite difficult. However, some tentative evidence for their existence exists.
In Italy the debate over the escape of brilliant young scientists to foreign countries has been going on for decades now. Italians like to debate, much less to solve their own problems. So although the problem is clearly identified and a recipe to solve it is evident, nobody does anything to implement the solution. Which, of course, would be to raise salaries to researchers and allow for quicker and easier ways to access a career for young post-docs.
The 14 year old kid in the picture on the right was named Aitzaz Hasan Bangash. His name is a difficult one to remember for westerners, but that is a pity, because he ended his life as a true hero.
Last Monday Aitzaz was lingering out of school with two friends in the small shiite town of Ibrahimzai, near the Pakistani capital Islamabad. Just before getting in they were approached by a 20-year-old who claimed he wanted to enrol to the school. The students realized that he was concealing a bomb and planned to blow up the school.
At the 1962 Rochester conference in Geneva, the prediction that a particle later called the Omega minus should exist, already proposed in a paper by Glashow and Sakurai, was not considered important enough to be mentioned in any invited or contributed talk. It was mentioned in a comment from the floor by Gell-Mann. The paper proposing the existence of quarks was accepted by Physics Letters only because it had Gell-Mann's name on it. The editor said, "The paper looks crazy, but if I accept it and it is nonsense, everyone will blame Gell-Mann and not Physics Letters. If I reject it and it turns out to be right, I will be ridiculed."
Harry Lipkin, "Quark Models and Quark Phenomenology
", in "The Rise of the Standard Model", Cambridge UP 1997