tag:blogger.com,1999:blog-7315236707728759521.post663073882029453643..comments2023-02-05T23:50:08.133-07:00Comments on Dispatches From Turtle Island: Strong Force Coupling Constant Measured With Unprecedented AccuracyAndrew Oh-Willekehttp://www.blogger.com/profile/02537151821869153861noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-7315236707728759521.post-76672781494515375462019-02-25T11:33:37.935-07:002019-02-25T11:33:37.935-07:00The FLAG group, similar to the Particle Data Group...The FLAG group, similar to the Particle Data Group has a meg (roughly 450 page) update on fundamental constant measurements including the strong force coupling constant.<br /><br />https://arxiv.org/abs/1902.08191andrewhttps://www.blogger.com/profile/08172964121659914379noreply@blogger.comtag:blogger.com,1999:blog-7315236707728759521.post-58891452143752689112019-02-24T15:05:47.543-07:002019-02-24T15:05:47.543-07:00Good catch. That value is, of course, on the low s...Good catch. That value is, of course, on the low side, but at two sigma, all of the recent values are consistent with each other. Some global estimates including data more recent than the current PDG value claim a MOE of as little as +/- 0.0007 for the combined measurement.<br /><br />I'm inclined not to read too much into Lambda_QCD, but the coincidence is still interesting.andrewhttps://www.blogger.com/profile/08172964121659914379noreply@blogger.comtag:blogger.com,1999:blog-7315236707728759521.post-28057736064330393052019-02-24T00:02:10.476-07:002019-02-24T00:02:10.476-07:00There was also a paper this week, arxiv:1902.08148...There was also a paper this week, arxiv:1902.08148, claiming to obtain αs(MZ)=0.1172(11) from a lattice calculation. Unfortunately I can't even tell what they use as the input for this calculation (perhaps the pion mass?). <br /><br />There is also a remark deep in the paper about consistently obtaining a best fit for the Lambda_QCD scale (where strong coupling takes over), in the MS-bar renormalization framework, of 313 MeV. Of course that's one third of the proton mass, and so an old value for the mass of a "constituent" quark, but it's also Brannen's mass scale for the original Koide triple, so it's always interesting to see claims from orthodox QCD that exactly 313 MeV (and not some other nearby value) is objectively significant in QCD. Mitchellhttps://www.blogger.com/profile/10768655514143252049noreply@blogger.com