(Press-News.org) TEMPE, Ariz. – One of the biggest mysteries in contemporary particle physics and cosmology is why dark energy, which is observed to dominate energy density of the universe, has a remarkably small (but not zero) value. This value is so small, it is perhaps 120 orders of magnitude less than would be expected based on fundamental physics.
Resolving this problem, often called the cosmological constant problem, has so far eluded theorists.
Now, two physicists – Lawrence Krauss of Arizona State University and James Dent of University of Louisiana-Lafayette – suggest that the recently discovered Higgs boson could provide a possible "portal" to physics that could help explain some of the attributes of the enigmatic dark energy and help resolve the cosmological constant problem.
In their paper, "Higgs Seesaw Mechanism as a Source for Dark Energy," Krauss and Dent explore how a possible small coupling between the Higgs particle, and possible new particles likely to be associated with what is conventionally called the Grand Unified Scale – a scale perhaps 16 orders of magnitude smaller than the size of a proton at which the three known non-gravitational forces in nature might converge into a single theory – could result in the existence of another background field in nature in addition to the Higgs field, which would contribute an energy density to empty space of precisely the correct scale to correspond to the observed energy density.
The paper is published on line today (Aug. 9), in Physical Review Letters.
Current observations of the universe show it is expanding at an accelerated rate. But this acceleration cannot be accounted for on the basis of matter alone. Putting energy in empty space produces a repulsive gravitational force opposing the attractive force produced by matter, including the dark matter that is inferred to dominate the mass of essentially all galaxies, but which doesn't interact directly with light and therefore can only be estimated by its gravitational influence.
Because of this phenomenon and because of what is observed in the universe, it is thought that such 'dark energy' contributes up to 70 percent of the total energy density in the universe, while observable matter contributes only 2 to 5 percent, with the remaining 25 percent or so coming from dark matter.
The source of this dark energy and the reason its magnitude matches the inferred magnitude of the energy in empty space currently is not understood, making it one of the leading outstanding problems in particle physics today.
"Our paper makes progress in one aspect of this problem," said Krauss, a Foundation Professor in Arizona State University's School of Earth and Space Exploration and in Physics, and the director of the Origins Project at ASU. "Now that the Higgs boson has been discovered, it provides a possible 'portal' to physics at much higher energy scales through very small possible mixings and couplings to new scalar fields which may operate at these scales."
"We demonstrate that the simplest small mixing, related to the ratios of the scale at which electroweak physics operates, and a possible Grand Unified Scale, produces a possible contribution to the vacuum energy today of precisely the correct order of magnitude to account for the observed dark energy," Krauss explained. "Our paper demonstrates that a very small energy scale can at least be naturally generated within the context of a very simple extension of the standard model of particle physics."
While a possible advance in understanding the origin of dark energy, Krauss said the construct is only one step in the direction of understanding its mysteries.
"The deeper problem of why the known physics of the standard model does not contribute a much larger energy to empty space is still not resolved," he said.
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A new analysis of dinosaur fossils by University of Pennsylvania researchers has revealed that a number of specimens of the genus Psittacosaurus — once believed to represent three different species — are all members of a single species. The differences among the fossil remains that led other scientists to label them as separate species in fact arose from how the animals were buried and compressed, the study found.
"Because of the vagaries of fossilization, no two fossils are the same," said senior author Peter Dodson, professor of anatomy in Penn's School of Veterinary ...
A team of chemists in SU's College of Arts and Scientists has used a temperature-sensitive polymer to regulate DNA interactions in both a DNA-mediated assembly system and a DNA-encoded drug-delivery system.
Their findings, led by Associate Professor Mathew M. Maye and graduate students Kristen Hamner and Colleen Alexander, may improve how nanomaterials self-assemble into functional devices and how anticancer drugs, including doxorubicin, are delivered into the body. More information is available in a July 30 article in ACS Nano, published by the American Chemical Society.
One ...
Tropical Depression 11W formed in the western North Pacific Ocean and appears to be tracking toward Luzon, in the Northern Philippines. NASA's Aqua satellite captured an infrared image of the tropical depression as it continues to organize and strengthen.
On Aug. 8 at 1853 UTC (2:53 p.m. EDT) NASA's Atmospheric Infrared Sounder or AIRS instrument that flies aboard NASA's Aqua satellite showed some cloud top temperatures in bands of thunderstorms and around the center of Tropical Depression 11W were as cold as -63F/-52C, indicating strong storms.
What does Infrared ...
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Chemists in The College of Arts and Sciences have figured out how to synthesize nanomaterials with stainless steel-like interfaces. Their discovery may change how the form and structure of nanomaterials are manipulated, particularly those used for gas storage, heterogeneous catalysis and lithium-ion batteries.
The findings are the subject of a July 24 article in the journal Small (Wiley-VCH, 2013), co-authored by associate professor Mathew M. Maye and research assistant Wenjie Wu G'11, G'13.
Until now, scientists have used many wet-chemical approaches—collectively known ...
New research on two promising gene therapies suggests that combining them into one treatment not only repairs muscle damage caused by Duchenne muscular dystrophy, but also prevents future injury from the muscle-wasting disease. The work, led by a team at The Research Institute at Nationwide Children's Hospital, is the first to look at the approach in aged mice, a key step toward clinical trials in patients. The findings were published in July in Human Molecular Genetics.
"We're excited about the fact that these are older mice and we're still able to see a sustained functional ...
LOS ANGELES (Aug. 9, 2013) – A unique nanoscale drug that can carry a variety of weapons and sneak into cancer cells to break them down from the inside has a new component: a protein that stimulates the immune system to attack HER2-positive breast cancer cells.
The research team developing the drug – led by scientists at the Nanomedicine Research Center, part of the Maxine Dunitz Neurosurgical Institute in the Department of Neurosurgery at Cedars-Sinai Medical Center – conducted the study in laboratory mice with implanted human breast cancer cells. Mice receiving the ...
Contact: Marco Leyton, Ph.D.
marco.leyton@mcgill.ca
514-398-5804
McGill University
Terry E. Robinson, Ph.D.
ter@umich.edu
734-358-8055
The University of Michigan
Alcoholism: Clinical & Experimental Research
Brain dopamine may serve as a risk marker for alcohol use disorders
There are known risks for and protective factors against the development of alcohol use disorders (AUDs).
A new study has found that striatal dopamine responses to alcohol ingestion may serve as a neurobiological marker of vulnerability to AUDs.
Specifically, when given alcohol, ...
Research from McGill University suggests that people who are vulnerable to developing alcoholism exhibit a distinctive brain response when drinking alcohol, according to a new study by Prof. Marco Leyton, of McGill University's Department of Psychiatry. Compared to people at low risk for alcohol-use problems, those at high risk showed a greater dopamine response in a brain pathway that increases desire for rewards. These findings, published in the journal Alcoholism: Clinical & Experimental Research, could help shed light on why some people are more at risk of suffering ...
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Hot, dry and windy weather played a role in that wildfire, said Don Smurthwaite, spokesperson with the National Interagency Fire Center (NIFC) in Boise, Idaho.
"Fire seasons are getting longer, western regions are getting drier, and more people are living ...
