Feeds

US boffins charged with parity violations

Seeking lost bosons

  • alert
  • submit to reddit

Secure remote control for conventional and virtual desktops

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

Boost IT visibility and business value

More from The Register

next story
Our LOHAN spaceplane ballocket Kickstarter climbs through £8000
Through 25 per cent but more is needed: Get your UNIQUE rewards!
Cutting cancer rates: Data, models and a happy ending?
How surgery might be making cancer prognoses worse
Boffins ID freakish spine-smothered prehistoric critter: The CLAW gave it away
Bizarre-looking creature actually related to velvet worms
CRR-CRRRK, beep, beep: Mars space truck backs out of slippery sand trap
Curiosity finds new drilling target after course correction
SpaceX prototype rocket EXPLODES over Texas. 'Tricky' biz, says Elon Musk
No injuries or near injuries. Flight stayed in designated area
Brit balloon bod Bodnar overflies North Pole
B-64 amateur ultralight payload approaching second circumnavigation
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
5 things you didn’t know about cloud backup
IT departments are embracing cloud backup, but there’s a lot you need to know before choosing a service provider. Learn all the critical things you need to know.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?