Feeds

US boffins charged with parity violations

Seeking lost bosons

  • alert
  • submit to reddit

High performance access to file storage

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

High performance access to file storage

More from The Register

next story
Video games make you NASTY AND VIOLENT
Especially if you are bad at them and keep losing
Elon Musk's LEAKY THRUSTER gas stalls Space Station supply run
Helium seeps from Falcon 9 first stage, delays new legs for NASA robonaut
Solar-powered aircraft unveiled for round-the-world flight
It's going to be a slow and sleepy flight for the pilots
Russian deputy PM: 'We are coming to the Moon FOREVER'
Plans to annex Earth's satellite with permanent base by 2030
LOHAN's Punch and Judy show relaunches Thursday
Weather looking good for second pop at test flights
Saturn spotted spawning new FEMTO-MOON
Icy 'Peggy' looks to be leaving the outer rings
Discovery time for 200m WONDER MATERIALS shaved from 4 MILLENNIA... to 4 years
Alloy, Alloy: Boffins in speed-classification breakthrough
India's GPS alternative launches second satellite
Closed satnav system due to have all seven birds aloft by 2016
Curiosity finds not-very-Australian-shaped rock on Mars
File under 'messianic pastries' and move on, people
prev story

Whitepapers

Mainstay ROI - Does application security pay?
In this whitepaper learn how you and your enterprise might benefit from better software security.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Mobile application security study
Download this report to see the alarming realities regarding the sheer number of applications vulnerable to attack, as well as the most common and easily addressable vulnerability errors.