Saturday, June 25, 2011

Neutrino News II

Thanks to Chimp, we note that MINOS now weighs in with a positive $\theta_{13}$ result, in agreement with T2K. The new excess suggests a value somewhere near the lower end of the T2K range, around $0.04$ for $\sin^{2} 2 \theta_{13}$. But further data is required to verify this non zero value for the muon electron phase.


  1. Of course, MINOS is our favourite neutrino experiment and we commend their previous accurate mixing results! A small $\theta_{13}$ would extend the Koide variables in the third 'dimension' of triality; not a bad thing theoretically, although we may not properly understand the phenomenology yet ...

  2. Kea, since the MINOS result is in "... a range between 0 and 0.12..." according to a Fermilab press release,
    it is also consistent with sin22theta13 = 0

    As I said over on Tommaso's blog:

    Carl and Paolo said substantially what Kea said in her blog:
    "... all candidate events occured in one region of the Superkamiokande tank ..."
    based on the information in slide 54 of the T2K presentation by Ken Sakashita, a copy of which I put on the web at

    The distribution looks very suspiciously anomalous to me, and I may remain suspicious of any nonzero sin22theta13 until the Daya Bay results come in. As to when that might be, I put up a copy of slide 5 of a Daya Bay presentation by Yifang Wang on the web at

    I have added a horizontal black line at the value 0.03 that has been claimed at 2.5 sigma by T2K. You can see from the Daya Bay slide that (if all goes well) the 0.03 value should be either seen (at 3 sigma) or excluded by Daya Bay before the end of this year 2011.

    Also, the Daya Bay slide indicates that T2K will not be able to have a sensitivity limit (90 per cent CL) of 0.03 until around 2014 at the earliest.

    That makes me think that T2K is under extreme time pressure from its Daya Bay competitor, and so may be pushing the limits of its capabilites, perhaps neglecting suspicious circumstances as the distribution of the 6 T2K events.


  3. Thanks a lot, Tony, that's very interesting. Of course, from the Koide formula point of view a zero value is easier to understand: it gives the already successful charged lepton formula exactly, after all. So our theoretical prejudices did, and still do, predict a zero value. However, it is perhaps not that critical, theoretically, from the M theory triality point of view, which should eventually clarify the Koide relations. Ie, we need to better understand how the quarks and leptons complement each other.


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