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Jacob Anderson | USLHC | USA

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Matter and anti-matter

Recently the D0 collaboration at the Tevatron announced an interesting result.  Having come from the BaBar experiment and worked on CP violation, I found it exciting.  Our universe is dominated by matter.  It’s everywhere and there is almost no anti-matter to be found.  This is one of the principle questions in our sub-atomic understanding of the universe.  The answer to this was put forward many years ago by Sakharov; there has to be CP violation, meaning that the swapping a particle with its anti-particle and looking at the interaction in a mirror can’t be the same as the original.

CP violation was discovered several years ago and has already won Nobel prizes.  The B-factories have measured many of the CP violating parameters of the Standard Model and come up with a rather coherent picture.  These measurements and constraints are embodied in the CKM triangle, where the height of the triangle is a measure of the amount of CP violation.


CKM Triangle

Recent CKM fitter result

It’s beautiful really.  Like a piece of fine art.


Kandinsky composition VIII

Kandinsky Composition VIII

There is just one problem; the amount of CP violation is insufficient by about 10 orders of magnitude. This means that there has to be more CP violation out there that we don’t know anything about.

This is where D0 comes in. They have been looking at CP violation in decays that aren’t accessible at the B-factories, and they found something. The Standard Model says they shouldn’t find much at all, but they did. I think it’s exciting. This isn’t the first sign of stress on the Standard Model, and there will undoubtedly be more coming in the next few years from LHC and other experiments. I think it is an exciting time to be involved in fundamental science research since we will be revising and rewriting many long held theories in the coming decades.


D0 result

D0 asymmetry result is separated from the Standard Model representing the blue point.
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2 Responses to “Matter and anti-matter”

  1. Flip Tanedo says:

    Hi Jake — can you remark about the extent to which CDF/ATLAS/CMS/LHCb can check this result (and the rough timescale for such an analysis to be done)?

    Is D0 much better suited for this than CDF? (i.e. do we have to wait for [some number]/fb at the LHC for more data on this?)

    Cheers,
    Flip

  2. Jake Anderson says:

    Flip, I know that D0 is particularly suited for this type of asymmetry measurement because the regularly swap magnet polarizations. At the LHC, I can’t say how long it would take to accumulate a comparable data sample. The b cross section is certainly higher, but I don’t know really by what factor.
    -Jake

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