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.

A bound on the natural width of the Higgs boson

A bound on the natural width of the Higgs boson: In the Standard Model, the Higgs boson is expected to be very narrow: its width is roughly 4 MeV, a good 30,000 times smaller than the central mass of approximately 125 GeV...

The width is usually determined from the distribution of masses observed. In this case, however, the expected width is much smaller than the experimental resolution of the mass measurement...

A quantitative analysis leads to an upper bound on the Higgs width of ~4 times that of the Standard Model value, approximately 17 MeV. This is a huge improvement, of a factor of 200 over the previous bound.

'Accelerator on a chip' demonstrated

'Accelerator on a chip' demonstrated: ...electrons are first accelerated to near light-speed in a conventional accelerator. Then they are focused into a tiny, half-micron-high channel within a fused silica glass chip just half a millimeter long. The channel had been patterned with precisely spaced nanoscale ridges. Infrared laser light shining on the pattern generates electrical fields that interact with the electrons in the channel to boost their energy.

Physicists Build Super-Powerful Tabletop Particle Accelerator | Popular Science

Physicists Build Super-Powerful Tabletop Particle Accelerator | Popular Science: "We have accelerated about half a billion electrons to 2 gigaelectronvolts over a distance of about 1 inch," Mike Downer, professor of physics says in a statement. "Until now that degree of energy and focus has required a conventional accelerator that stretches more than the length of two football fields. It's a downsizing of a factor of approximately 10,000..."

In order to create electrons of the energy level required to produce these X-rays, the team employed laser-plasma acceleration, which involves firing a brief but intensely powerful laser pulse into a puff of gas, using the Texas Petawatt Laser. Though the method was conceived of in the 1970s, a lack of sufficiently powerful lasers to perform it has kept scientists limited at 1 GeV accelerators.

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...”

Higgs boson continues to be maddeningly well-behaved

Higgs boson continues to be maddeningly well-behaved: Today, experimentalists from CMS and the other main LHC detector ATLAS, armed with twice as much data as they had in July, told the Hadron Collider Physics symposium in Kyoto, Japan, that the number of tau particles detected has crept up. The new data can't yet rule out a deviation from the standard model but they do remove the main reason for thinking there was one in the first place...
...direct searches for new physics at the LHC have turned up empty too. Physicists presented searches for dozens of particles that would exist in a world governed by some of these new theories...
"The results really tell us that we're either not looking in the right place, or we're not looking in the right way, or maybe both..."

Researchers at SLAC find too many taus decay from bottom quarks to fit Standard Model

Researchers at SLAC find too many taus decay from bottom quarks to fit Standard Model: Instead of the 20% frequency rate predicted for D mesons, the researchers found a 31% rate (and a 25% rate for D* mesons instead of the predicted 23%)...

To explain the differences between the theories and observed results the researchers suggest that perhaps another Higgs Boson is at work; SUSY suggests there may be as many as four, though research at CERN is still ongoing to prove that what was observed earlier this year was in fact an actual Higgs.

Physicists propose factory to spew out Higgs particles

Physicists propose factory to spew out Higgs particles:   Muons are particles similar to electrons, but 200 times more massive. That means a muon-antimuon accelerator could reach the necessary energies over a far shorter distance.

With the putative Higgs checking in at about 125 gigaelectronvolts, you would need to bash together a muon and an antimuon with each having just over 60 GeV of energy. "That should be doable with a machine 100 times smaller than the LHC," says Rubbia. The result would be a "Higgs factory" producing the particle and little else.

Superstuff: When quantum goes big

Superstuff: When quantum goes big: Imagine you have two identical particles, and you swap their positions. The physical system looks exactly the same, and responds to an experiment exactly as before. However, quantum theory records the swap by multiplying their quantum state by a "phase factor". Switching the particles again brings in the phase factor a second time, but the particles are in their original position and so everything returns to its original state. "Since switching the particles twice brings you back to where you were, multiplying by this phase twice must do nothing at all," says John Baez at the Centre for Quantum Technologies in Singapore. This means that squaring the phase must give 1, which in turn means that the phase itself can be equal to 1 or -1.

What if there is no Higgs boson?

What if there is no Higgs boson?:  Physicists are only looking for the Higgs particle because it is the easiest way to access the field. If they don't see it, then it suggests the field is different from the one predicted by the standard model. Normally, particles in fields are like ripples in ponds – photons are ripples in the electromagnetic field, for example. But if the field is more like molasses than water, then the ripples die away too quickly for us to detect.

That means matter might get its mass from a thick Higgs-like field that has no associated particle. To get such a goopy field, theorists need to add in more exotic possibilities – such as new particles or forces of nature...

The existence of a new force, called technicolour, could also give particles mass without the need for a Higgs boson. Technicolour would act like a heavy-duty version of the strong nuclear force, which binds quarks together in the nuclei of atoms. The technicolour force would fill space with pairs of still more new particles, which would form a soup through which other particles would travel, gaining mass in the process....

The existence of a fourth dimension of space, beyond the three we experience, could explain why particles have different masses – a fact that is usually attributed to the Higgs boson.

Proof Found for Unifying Quantum Principle

Proof Found for Unifying Quantum Principle: His conjecture is called the a-theorem. It says that the number of ways in which quantum fields can be energetically excited (a) is always greater at high energies than at low energies...

Although lots of work has gone into relating short- and long-distance scales for particular quantum field theories, there are relatively few general principles that do this for all theories that can exist...
But Cardy's a-theorem could be one such principle. A version of it had already been proven in two dimensions, but Cardy proposed that it might hold in four dimensions--such as the three dimensions of space and one of time that exist in the space in which we live.

Black Holes, Safety, and the LHC Upgrade - Technology Review

Black Holes, Safety, and the LHC Upgrade - Technology Review: These guys assume that after microscopic black holes form, they would go through four phases. First there is the balding phase in which the newly formed back hole evolves from a highly asymmetric object to a more symmetric one, shedding its asymmetry through gravitational radiation.

In the second phase, called the spin-down phase, the black hole loses mass and angular momentum by emitting Hawking radiation. The third, the Schwarzschild phase, the black hole becomes spherical and the rate of mass loss slows down. And in the final Planck phase, the black hole winks out of existence.

Neutrinos Travel Faster Than Light, According to One Experiment - ScienceNOW

Neutrinos Travel Faster Than Light, According to One Experiment - ScienceNOW: Over 3 years, OPERA researchers timed the roughly 16,000 neutrinos that started at CERN and registered a hit in the detector. They found that, on average, the neutrinos made the 730-kilometer, 2.43-millisecond trip roughly 60 nanoseconds faster than expected if they were traveling at light speed. "It's a straightforward time-of-flight measurement..."
...the tricky part is accurately measuring the time between when the neutrinos are born by slamming a burst of protons into a solid target and when they actually reach the detector. That timing relies on the global positioning system, and the GPS measurements can have uncertainties of tens of nanoseconds. "I would be very interested in how they got a 10-nanosecond uncertainty, because from the systematics of GPS and the electronics, I think that's a very hard number to get."

Pocket Particle Accelerators Like This One Could Bring Safer Nuclear Power to Neighborhoods | Popular Science

Pocket Particle Accelerators Like This One Could Bring Safer Nuclear Power to Neighborhoods | Popular Science:  Nicknamed EMMA — the Electron Model of Many Applications — the accelerator would be used to jump-start fissile nuclear reactions inside a small-scale thorium power plant.

Thorium reactors would not melt down, in part because they require an external input to produce fission. Thorium atoms would release energy when bombarded by high-energy neutrons, such as the type supplied in a particle accelerator.
Providing that stimulus is one obstacle to building small thorium reactors — but a new generation of accelerators like EMMA, and someday potentially even smaller, luggage-sized ones — could do the job.

Observations: Evidence Mounts for New Physics via the Tevatron Particle Collider

Observations: Evidence Mounts for New Physics via the Tevatron Particle Collider: "High-speed smash-ups between protons and their antimatter counterparts, observed by the Illinois site's CDF detector, appeared to yield a certain kind of package in unexpected abundance: a massive particle known as the W boson along with two jets of other particles. The CDF excess hinted at the existence of some unknown particle..."

Densest Matter Created in Big-Bang Machine

Densest Matter Created in Big-Bang Machine: Some theories predict that, in the extreme heat of the very early universe, quarks and gluons would have been even more widely spaced, creating a quark-gluon plasma that behaved like a gas. The ALICE team is therefore looking for evidence of gas-like behavior in the early stages of their quark-gluon plasma formation...
"It could well be that in the very early stages [of our quark-gluon plasma], it's behaving more like a gas, and then as it cools it turns into a liquid, but we will need to investigate this further..."
If this gas-to-liquid transition has indeed been observed, it would be surprising, since theory predicts that it should occur at much higher temperatures than those currently being produced at the LHC, said Thomas Ludlam, chair of the physics department at Brookhaven.

Scientists Abuzz Over Controversial Rumor that God Particle Has Been Detected | Quantum Physics & Particle Physics | Large Hadron Collider & Higgs Boson | LiveScience

Scientists Abuzz Over Controversial Rumor that God Particle Has Been Detected | Quantum Physics & Particle Physics | Large Hadron Collider & Higgs Boson | LiveScience: "Some physicists say the note may be a hoax, while others believe the 'detection' is likely a statistical anomaly that will disappear upon further study. But the find would be a huge particle-physics breakthrough, if it holds up..."

"Its production rate is much higher than that expected for the Higgs boson in the Standard Model," Stone told SPACE.com in an email interview. So the signal may be evidence of some other particle, Stone added, "which in some sense would be even more interesting, or it could be the result of new physics beyond the Standard Model."

Ultra-fast magnetic reversal observed

Ultra-fast magnetic reversal observed: In their experiment, the scientists studied an alloy of gadolinium, iron and cobalt (GdFeCo), in which the magnetic moments naturally align antiparallel. They fired a laser pulse lasting 60 femtoseconds at the GdFeCo and observed the reversal using the circular-polarized X-ray light, which also allowed them to distinguish the individual elements. What they observed came as a complete surprise: The Fe atoms already reversed their magnetization after 300 femtoseconds while the Gd atoms required five times as long to do so. That means the atoms were all briefly in parallel alignment, making the material strongly magnetized. "This is as strange as finding the north pole of a magnet reversing slower than the south pole," says Ilie Radu.

Ultra-fast magnetic reversal observed

Ultra-fast magnetic reversal observed: For their experiment, the researchers needed an ultra-short laser pulse to heat the material and thus induce magnetic reversal. They also needed an equally short X-ray pulse to observe how the magnetization changed. This unique combination of a femtosecond laser and circular polarized, femtosecond X-ray light is available in one place in the world: at the synchrotron radiation source BESSY II in Berlin, Germany.

In their experiment, the scientists studied an alloy of gadolinium, iron and cobalt (GdFeCo), in which the magnetic moments naturally align antiparallel. They fired a laser pulse lasting 60 femtoseconds at the GdFeCo and observed the reversal using the circular-polarized X-ray light, which also allowed them to distinguish the individual elements. What they observed came as a complete surprise: The Fe atoms already reversed their magnetization after 300 femtoseconds while the Gd atoms required five times as long to do so. That means the atoms were all briefly in parallel alignment, making the material strongly magnetized.

Mystery signal at Fermilab hints at 'technicolour' force - physics-math - 07 April 2011 - New Scientist

Mystery signal at Fermilab hints at 'technicolour' force : Just over 20 years ago, Lane, along with Fermilab physicist Estia Eichten, predicted that experiments would see just such a signal. Lane and Eichten were working on a theory known as technicolour, which proposes the existence of a fifth fundamental force in addition to the four already known: gravity, electromagnetism, and the strong and weak nuclear forces. Technicolour is very similar to the strong force, which binds quarks together in the nuclei of atoms, only it operates at much higher energies. It is also able to give particles their mass – rendering the Higgs boson unnecessary.

The new force comes with a zoo of new particles. Lane and Eichten's model predicted that a technicolour particle called a technirho would often decay into a W boson and another particle called a technipion.

In a new paper, Lane, Eichten and Fermilab physicist Adam Martin suggest that a technipion with a mass of about 160 GeV could be the mysterious particle producing the two jets. "If this is real, I think people will give up on the idea of looking for the Higgs and begin exploring this rich world of new particles," Lane says.