Feeds

US boffins charged with parity violations

Seeking lost bosons

  • alert
  • submit to reddit

Choosing a cloud hosting partner with confidence

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

Choosing a cloud hosting partner with confidence

More from The Register

next story
Boffins say they've got Lithium batteries the wrong way around
Surprises at the nano-scale mean our ideas about how they charge could be all wrong
Edge Research Lab to tackle chilly LOHAN's final test flight
Our US allies to probe potential Vulture 2 servo freeze
Europe prepares to INVADE comet: Rosetta landing site chosen
No word yet on whether backup site is labelled 'K'
Cracked it - Vulture 2 power podule fires servos for 4 HOURS
Pixhawk avionics juice issue sorted, onwards to Spaceport America
Archaeologists and robots on hunt for more Antikythera pieces
How much of the world's oldest computer can they find?
Bacon-related medical breakthrough wins Ig Nobel prize
Is there ANYTHING cured pork can't do?
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
The next step in data security
With recent increased privacy concerns and computers becoming more powerful, the chance of hackers being able to crack smaller-sized RSA keys increases.