Breaking News

Two midday breaking news items:

  • The ACME II experiment is reporting today a new, nearly order of magnitude better, limit on the electric dipole moment of the electron:
    $$|d_e|\leq 1.1 \times 10^{-29} e\ cm$$
    The previous best bound was from ACME I in 2014:
    $$|d_e|\leq 9.4 \times 10^{-29} e\ cm$$

    One significance of this is that while the SM prediction for the electron EDM is unobservably small, generically extensions of the SM predict much larger values. Already the 2014 bound was in conflict with typical SUSY models with LHC-scale supersymmetry, and was starting to rule out parts of the ranges expected for split-SUSY models (Arkani-Hamed’s current “best bet”) as well as the expected range for SO(10) GUTs (see for instance slide 25 here).

    Today’s result pretty much completely rules out generic versions for both the most popular SUSY models still standing (Split SUSY), as well as the most popular class of GUTs. This provides another nail in the coffin of the SUSY-GUT paradigm which has dominated expectations for physics beyond the SM over the past forty years.

  • The Breakthrough Prize people are having their usual sort of ceremony for the 2019 prizes on November 4, with an Oscars-like production, this year hosted by Pierce Brosnan. In a break with the past, this year they’re announcing the winners in advance, see here. The $3 million physics prize goes to Kane and Mele for their work on topological insulators.

    The $3 million mathematics prize goes to Vincent Lafforgue, for his work on the Langlands correspondence. The prize description has some information about him I was unaware of:

    Deeply concerned about the ecological crisis, Lafforgue is now focused on operator algebras in quantum mechanics and devising new materials for clean energy technologies.

Update: The promotional videos for the Breakthrough Prize winners that will be shown at the November ceremony are already available on Youtube.

Update: Those phenomenologists work fast! A detailed study of the implications of the ACME result for SUSY models is on the arXiv tonight. For a precise version of the crude claim that “generic split SUSY is now ruled out”, look at the top two plots in figure 4.

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9 Responses to Breaking News

  1. Rob says:

    Is it really the case that this new limit kills off “pretty much completely rules out generic versions for both the most popular SUSY models still standing (Split SUSY), as well as the most popular class of GUTs” ? This limit is only largely sensitive to CP-violating SUSY. Sure – there are a lot of CP-violating phases in the MSSM but, in true model-building fashion, they can be turned off.

  2. Peter Woit says:

    Rob,
    Absent some compelling motivation other than avoiding being ruled out by experiment, I think it’s appropriate to describe models with CP-violating phases turned off as “non-generic”.

  3. \times, not x, please.

  4. Peter Woit says:

    David Roberts,

    OK, OK… Fixed.

  5. Rob says:

    Peter – following your definition of generic, the ACME II result may actually be fairly insensitive to generic SUSY. There is no compelling theoretical reason to keep R-parity conserved, an assumption on which popular SUSY models are based. As you know, R-parity conservation is imposed to stop the observed stability of the proton killing SUSY.

    This is of course all getting a bit absurd….

  6. Shantanu says:

    Does anyone know what version of SUSY, Pierre Ramond supports/supported when he said that Super- K results on neutrino mass point to evidence for low-energy SUSY?
    (See https://physics.aps.org/focus/supplement/neutrinoquotes.html)
    and this version of SUSY still alive?

  7. minor memory says:

    The joke at the time Laurent Lafforgue got the Fields Medal was “the committee awarded the medal to Lafforgue… they gave it to the wrong one”.

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