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Lepton Universality In Question, a Standard Model Assumption

Posted by Soulskill on from the we'ere-slightly-more-wrong-than-we-thought dept.

Charliemopps writes: "Over the past few years, more and more experiments have started to question one of the core assumptions of the standard model: Lepton Universality. Simply put, the weak nuclear force is assumed to work equally on all Leptons (electron, muon and tau). Two years ago The Babar experimental collaboration reported that measurements indicated this may not have been the case. But the measurements were not accurate enough to be definitive.

Now, a report from The LHC shows that they have analyzed their entire dataset of proton-proton collisions and found a rather large discrepancy. These measurements are still not all that accurate. These decays happen so rarely that even with this huge data set there is still about a 1% change they are incorrect. One explanation for such measurements is an as-yet-undiscovered, charged Higgs particle. It would have to be extremely heavy: greater than 109GeV possibly even as high as 150GeV. This is predicted by some models outside of the Standard Model, like Supersymmetry."

6 of 62 comments (clear)

  1. No Problem: by Tablizer · · Score: 4, Funny

    To "fix" it, just add one or more of the following to the model:

    * More turtles
    * More nested epicycles
    * More dimensions
    * Invent dark [something] to plug it
    * Say God did it

    Profit!

    --
    Table-ized A.I.
    1. Re:No Problem: by Anonymous Coward · · Score: 5, Insightful

      Just remember if you propose a new thoery that can explain the data and make quantitative, it still needs to past the most important test: the gut instinct of forum posters on the internet. They seem to act like science shouldn't propose new theories when new data conflicts with old theories... or insist new theories are ok, except for the ones they don't like.

  2. But... by Stormy+Dragon · · Score: 5, Informative

    This is predicted by some models outside of the Standard Model, like Supersymmetry.

    Except that that LHC's ongoing failure to find any SUSY particles is making it increasingly unlikely Supersymmetry is right either:

    http://scienceblogs.com/starts...

    1. Re:But... by jfengel · · Score: 4, Informative

      The data go a long way to ruling out the Minimal Supersymetric Standard Model (MSSM), but other SUSY theories are still in the running. The MSSM has the advantage of being, well, minimal, but there's no special reason to expect the universe to have made it that easy on us.

      It's hard to say which theory this points us to, if any, but the Two Higgs Doublet Model (2HDM) is a part of several. Those theories will help refine what kind of data to look for and what kinds of experiments to configure.

  3. Null experiment for the 21st century by Anonymous Coward · · Score: 4, Interesting

    With regards to Supersymmetry I have the feeling the LHC is going to end up being this century's version of Michelson-Morley.

    However, given what happened after Michelson-Morley, we may be in for some very exciting new physics in the years to come if we can disprove Supersymmetry.

    (At least I hope we are... :-))

  4. Re:Particles are more unique than thought by ceoyoyo · · Score: 4, Insightful

    And that's the problem with applying pop logic to a fuzzy understanding of a vastly simplified description.

    Modern quantum theory suggests not only that two examples of the same type of particle are not only completely identical except for certain features like position, but that even talking about particles as if they had individual existence doesn't really make sense.