LHC spots particle that may be new form of matter - physics-math - 10 April 2014 - New Scientist

LHC spots particle that may be new form of matter - physics-math - 10 April 2014 - New Scientist: Now that Z(4430)'s existence is confirmed, the next challenge is to work out whether it really is a tetraquark.

There is at least one reason why physicists can be hopeful. The other suspected tetraquarks might simply be loosely bound pairs of mesons, says Marek Karliner, a theorist at Tel Aviv University in Israel, who was not part of the team. Z(4430) is different because its mass does not seem to allow for this.

Particle Containing 4 Quarks Is Confirmed for First Time

Particle Containing 4 Quarks Is Confirmed for First Time:  One side proposes that the particle is actually a union of two ordinary particles called mesons, which contain one quark and one antiquark. Zc(3900) particles could be made up of two mesons joined by a loose connection to form a molecule-like structure...



Other theorists have tentatively labelled the new particle a true tetraquark — four quarks stuck together tightly to form a compact ball...  Such pairings do not occur in any known particle and would thus introduce new building blocks of matter...

Proponents of the tetraquark theory point out that a ‘molecule’ made of mesons should split easily into two halves, and that such a breakdown has not appeared in the data. “The signature of a molecule is not seen, which favours the tetraquark picture...”

Asymmetric Quarks Defy Standard Model of Physics, Suggest New Gluon: Scientific American

Asymmetric Quarks Defy Standard Model of Physics, Suggest New Gluon: Scientific American:  In some superconductors, electrons pair up, bound by particle-like vibrations in the material. The bound electrons limit the range over which the electromagnetic force can act within the material, an effect that in turn imparts an effective mass to nearby photons -- particles of light, which carry the long-range electromagnetic force and are normally weightless.
 In a similar way, Hill suggests, top quarks and anti-top quarks might pair up throughout the cosmos, bound by a force carried by an as-yet undiscovered particle dubbed the top gluon. "It's as if the entire universe was a special kind of superconductor..."

Fermilab Data Hint At Possible New Particle - Science News

Fermilab Data Hint At Possible New Particle - Science News:  A new particle similar to but heavier than the W boson and Z boson would explain the observed excess. W and Z bosons are fundamental particles that transmit the weak force, which is responsible for radioactive decay...

Looking at collision products at energies between 120 billion and 160 billion electron volts, the physicists saw an unexpected peak: They found about 250 more such events than predicted by the standard model...

In an article that Hooper and colleagues posted online at arXiv.org on April 1 (arxiv.org/abs/1103.6035), they propose a particle that could explain both new findings. The team calculated that a hypothetical particle known as the Z’ boson, a heavier cousin of the Z boson with a proposed mass of 150 billion electron volts, could account for both results if the particle interacts strongly with quarks but avoids interactions with electrons and their heavier brothers, muons.

Bound neutrons pave way to free ones

Bound neutrons pave way to free ones: "'Take a quantity that tells you how strong the EMC Effect is. And then take another quantity that tells you how many short-range correlations you have,' Higinbotham explains. 'And you see that when one is big, the other one is big. When one is small, the other one is small.'
The scientists say that it's unlikely that one effect causes the other. Rather, the data shows that there is a common cause for both."

Void that is truly empty solves dark energy puzzle - physics-math - 01 September 2010 - New Scientist

Void that is truly empty solves dark energy puzzle: "People have just been taking it on faith that this quark condensate is present throughout the vacuum," says Brodsky. Instead, his team have assumed that the condensate exists only inside protons, neutrons, pions and all other quark-containing particles, collectively known as hadrons (Physical Review C, DOI: 10.1103/PhysRevC.82.022201).

"In our picture, quarks and gluons can't flutter in and out of existence unless they are inside hadrons," says team member Craig Roberts of the Argonne National Laboratory in Illinois. As a result, the vacuum is much calmer and, crucially, the problem it poses for the cosmological constant is reduced.

n 1974, Aharon Casher of Tel Aviv University in Israel and Leonard Susskind, now at Stanford University in California, suggested that a condensate present only inside hadrons could give these particles mass. Brodsky and colleagues are the first to show that this idea also helps resolve the dark energy discrepancy.

Explained: Quark gluon plasma

Explained: Quark gluon plasma: "If you’re interested in the properties of the microseconds-old universe, the best way to study it is not by building a telescope, it’s by building an accelerator"