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posted by janrinok on Friday August 14 2015, @02:53AM   Printer-friendly

In the most stringent test yet of differences between protons and antiprotons, scientists investigated the ratio of electric charge to mass in about 6,500 pairs of these particles over a 35-day period. To keep antimatter and matter from coming into contact, the researchers trapped protons and antiprotons in magnetic fields. Then they measured how these particles moved in a cyclical manner in those fields, a characteristic known as their cyclotron frequency, which is proportional to both the charge-to-mass ratio of those particles and the strength of the magnetic field.

(Technically, the researchers did not use simple protons in the experiments, but negative hydrogen ions, which each consist of a proton surrounded by two electrons. This was done to simplify the experiments — antiprotons and negative hydrogen ions are both negatively charged, and so respond the same way to magnetic fields. The scientists could easily account for the effects these electrons had during the experiments.

The scientists found the charge-to-mass ratio of protons and antiprotons "is identical to within just 69 parts per trillion," Ulmer said in a statement. This measurement is four times better than previous measurements of this ratio.

In addition, the researchers also discovered that the charge-to-mass ratios they measured do not vary by more than 720 parts per trillion per day, as Earth rotates on its axis and travels around the sun. This suggests that protons and antiprotons behave the same way over time as they zip through space at the same velocity, meaning they do not violate what is known as charge-parity-time, or CPT symmetry.
[...]
Using more stable magnetic fields and other approaches, the scientists plan to achieve measurements that are at least 10 times more precise than what they found so far, Ulmer said.

If matter and anti-matter are mirrors of each other, and were created in equal measure by the Big Bang, then where did all the anti-matter go?


See our related story: Time-Symmetric Formulation of Quantum Theory Provides New Understanding of Causality.

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  • (Score: 2) by PiMuNu on Friday August 14 2015, @09:06AM

    by PiMuNu (3823) on Friday August 14 2015, @09:06AM (#222749)

    -100 lt G_{+}/G_{-} lt 100

    meta: Is there any documentation on soylent markup? I never know how it is supposed to work...

    Starting Score:    1  point
    Karma-Bonus Modifier   +1  

    Total Score:   2  
  • (Score: 0) by Anonymous Coward on Friday August 14 2015, @09:23AM

    by Anonymous Coward on Friday August 14 2015, @09:23AM (#222754)

    Just use standard HTML entities and supported html tags (see the list below the comment form). However what is not discoverable (it was once published on a meta post, but otherwise seems to be documented nowhere, unfortunately) is the very useful fact that also the <sub> and <sup> tags are supported. So you could have written your line as

    &minus;100 &lt; G<sub>+</sub>/G<sub>&minus;</sub> &lt; 100

    to get

    −100 < G+/G < 100

    But are the bounds really −100 and 100? Seem to be quite imprecise bounds to me.