From this morning's seminar: The new experimental result from Fermilab Runs 1-6 combined is:
0.01165920705(148) which is 127 parts per billion. This exceeded their goal of 140 ppb.
Including the Brookhaven result in the global experimental average only slightly tweaks this result (by 10 * 10^-12 higher) because the average is inverse error weighted and the Brookhaven result has four times more uncertainty and is only modestly higher itself. Runs 4-6 whose results were announced today, slightly pulled up the total value. It's result was 5 * 10^-12 higher than the overall average.
A crude breakdown of the sources of the uncertainty in the final results was as follows (the 125 ppb uncertainty total differs from everything else that puts it at 127 ppb).
The 127 ppb uncertainty in the experimental result (i.e. 0.01165920705(148)) compares to a 530 ppb uncertainty in the 2025 White Paper predicted value of muon g-2 which is a(SM)(μ) = 116592033(62) × 10^−11 (530 ppb).
The experimental value minus the SM prediction is (375 ± 637) × 10^−12 which is a difference of about 0.6 sigma, which is a very strong global confirmation of the Standard Model of Particle Physics at low to moderate energies.
The world average value minus the SM prediction is (385 ± 637) × 10^−12 which is also a difference of about 0.6 sigma, which is a very strong global confirmation of the Standard Model of Particle Physics at low to moderate energies.
Most likely, the discrepancy is mostly due to the leading order hadronic vacuum polarization (LO HVP) calculation in the Standard Model prediction being about 0.5% low in a calculation with a ± 0.9% uncertainty.
This result disfavors the hypothetical X17 particle, since a 16.9 MeV fundamental boson would very likely have a significant effect on the anomalous magnetic moment of the 105.7 MeV muon.
The link to the Fermilab paper reporting this is here. It's abstract states:
A new measurement of the magnetic anomaly aµ of the positive muon is presented based on data taken from 2020 to 2023 by the Muon g−2 Experiment at Fermi National Accelerator Laboratory (FNAL). This dataset contains over 2.5 times the total statistics of our previous results. From the ratio of the precession frequencies for muons and protons in our storage ring magnetic field, together with precisely known ratios of fundamental constants, we determine aµ = 1165920710(162) × 10^−12 (139ppb) for the new datasets, and aµ = 1165920705(148) × 10^−12 (127ppb) when combined with our previous results. The new experimental world average, dominated by the measurements at FNAL, is aµ(exp) = 1165920715(145) × 10^−12 (124ppb). The measurements at FNAL have improved the precision on the world average by over a factor of four.
3 comments:
John Hawks has blogged
Ghost populations in human origins
Genetic models are finding more and more unknown lineages
geneticists have found expensive amount of DNA in the human genome that can be best explained in terms of Ghost populations and more and more unknown lineages
so how much ghost populations and more unknown lineages, before some version of multiregionalism, perhaps v2. multiregionalism central hypothesis is that many lineages mixed forming sapiens, neanderthals, deniosavans, and DNA supports that.
in some West African populations up to 19% of their DNA comes from unknown non-sapien admixture, possibly some african erectus or erectus descent. 19% is a lot
"Every person’s genome has a few stretches of DNA that stand out as different from most of humanity. Some are traces of ghost populations: ancient groups that became extinct, but not before contributing some of their own genes to other populations that survived.
Geneticists have identified some of these ghosts. Everyone shares some of these quirky sequences with Neanderthals or Denisovans, long-lost groups that persist today only within living people’s genomes. But other groups remain a mystery.
Ideas about ghost populations have become central to our understanding of human origins and evolution of other mammals. I’ve written about ghost hominins, ghost bonobos, and ghost gorillas. "
my view is 80% Recent African + 20% multiregional "ghosts"
https://www.johnhawks.net/p/ghost-populations-in-human-origins
i wonder why h sapiens sapiens outcompeted all other lineages
Other studies have suggested that the apparent ghost populations in Africa are due to population structure and methodological issues. IMHO, the jury is out and we don't know.
DNA has falsified the original RAO in the pure form
Why we are not all multiregionalists now
Chris Stringer 1
Affiliations
PMID: 24702983 DOI: 10.1016/j.tree.2014.03.001
By the early 1990s, the pendulum was moving in favour of RAO because fossil evidence began to be increasingly reinforced by the clear signals of mtDNA and Y-DNA in recent human samples. By the late 1990s, the pendulum had swung even further toward a pure RAO, with growing fossil, archaeological, and genetic data supporting this model, including the distinctiveness of the first Neanderthal mtDNA sequences recovered from 1997 onwards [6].
However, large amounts of autosomal DNA have now been recovered from Eurasian Neanderthals and from fragmentary fossils found in Denisova Cave, Siberia, revealing another ancient human population. Moreover, traces of this nonAfrican DNA, attributed to ancient interbreeding events, have been found in recent human genomes, indicating that they are not purely of recent African origin. These revelations have halted and reversed the pendulum swing, away from an absolute RAO. I would say that we are now looking at a version of RAO that most closely resembles Bräuer's early formulation (out of Africa+hybridisation), or perhaps a version of the assimilation model of Smith and Trinkaus, with a strong African predominance. If the evidence for archaic assimilation in living humans remains modest and is restricted to Africa and to the dispersal phase of modern humans from Africa, constituting less than 10% of our genome, I think ‘mostly out of Africa’ is the appropriate designation and, for me, that is still RAO.
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