Feeds

US boffins charged with parity violations

Seeking lost bosons

  • alert
  • submit to reddit

Intelligent flash storage arrays

Boffins testing the strength of the 'weak' charge of electrons have seen parity violations in electron-electron scattering for the first time. The results could eventually lead to a better understanding of why things have mass.

In very simple terms, parity is a measure of the left-right (or mirror) symmetry of nature. Its origins lie with Louis Pasteur's discovery of optical isomers: the ability of left or right handed molecules to rotate polarised light in opposite directions. Generally, left-handed and right-handed versions of things exist in equal quantities.

In fact, parity is conserved in three of the four fundamental forces: gravity, electromagnetism and the strong force are all symmetric. But the weak force is not - a surprising result when first observed in a famous 1956 experiment with the radioactive decay of cobalt.

The scientists used the Stanford Linear Accelerator (SLAC) to fire polarised electron beams at a liquid hydrogen target. They measured the rate at which the polarised electrons bounced off target electrons for both left and right handed polarisations. With this data, they could look for asymmetry in the result: i.e. did the target scatter left or right handed polarised electrons more?

They observed a difference of 175 parts per billion: a very slight tendency to scatter more of one than the other. Using this data, they calculated that the strength of the so-called weak charge was -0.053, plus or minus 0.011. The standard model predicts a strength of -0.046, so this is very good agreement.

Similar results have been obtained by smashing polarized electrons into positrons and creating Z0 particles (neutral particles that transmit the weak force), but where the difference is very large ~10%. What's new about this experiment is that is able to observe such a tiny asymmetry to yield a precise measurement of the weak charge at a very different energy scale, much below what is needed to directly create the Z0 particles.

Mike Woods, a scientist working on the experiment at SLAC, explained that this is important because precise measurements at different energy scales are needed to look for certain new physics effects. He noted: "Weak charge measurements are very topical in particle physics, in part because they give the best indirect constraints on the Higgs mass".

The Higgs boson, if it exists, would help explain why matter has mass. It is as yet only theoretical. If scientists can work out how heavy it is, they will know where to go looking for it. ®

Related stories

Boffins slow neutrons to 15mph
DNA-based nanobot takes a stroll
Boffins synthesise Bucky's baby brother

Providing a secure and efficient Helpdesk

More from The Register

next story
SECRET U.S. 'SPACE WARPLANE' set to return from SPY MISSION
Robot minishuttle X-37B returns after almost 2 years in orbit
LOHAN crash lands on CNN
Overflies Die Welt en route to lively US news vid
You can crunch it all you like, but the answer is NOT always in the data
Hear that, 'data journalists'? Our analytics prof holds forth
Experts brand LOHAN's squeaky-clean box
Phytosanitary treatment renders Vulture 2 crate fit for export
No sail: NASA spikes Sunjammer
'Solar sail' demonstrator project binned
Carry On Cosmonaut: Willful Child is a poor taste Star Trek parody
Cringeworthy, crude and crass jokes abound in Steven Erikson’s sci-fi debut
Origins of SEXUAL INTERCOURSE fished out of SCOTTISH LAKE
Fossil find proves it first happened 385 million years ago
Human spacecraft dodge COMET CHUNKS pelting off Mars
Odyssey orbiter yet to report, though - comet's trailing trash poses new threat
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Cloud and hybrid-cloud data protection for VMware
Learn how quick and easy it is to configure backups and perform restores for VMware environments.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.