CODATA Recommended Values of the Fundamental Physical Constants: 2006

Abstract

This paper gives the 2006 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use. Further, it describes in detail the adjustment of the values of the constants, including the selection of the final set of input data based on the results of least-squares analyses. The 2006 adjustment takes into account the data considered in the 2002 adjustment as well as the data that became available between 31 December 2002, the closing date of that adjustment, and 31 December 2006, the closing date of the new adjustment. The new data have led to a significant reduction in the uncertainties of many recommended values. The 2006 set replaces the previously recommended 2002 CODATA set and may also be found on the World Wide Web at physics.nist.gov/constants. ContentsGlossary * This report was prepared by the authors under the auspices of the CODATA Task Group on Fundamental Constants. The members of the task group are:

Muonic hydrogen and MeV forces

“…A recent publication [1] announced a measurement of the Lamb shift in muonic hydrogen that seems to require a value of the proton's radius, r p = 0.84184(67) fm, which differs by five standard deviations from the value given in the CODATA compilation [2], r p = 0.8768(69) fm. It is of course possible that the reason for the different values of r p extracted from muonic and electronic hydrogen lies within the standard model, involving subtle QED and/or hadronic effects.…”

QCD-scale modified-gravity universe

“…The relation between the gravitational constant G 0 ≡ G(q 0 ) ≡ (16πK 0 ) −1 from (2.1) and Newton's constant G N (Cavendish, 1798;Mohr, Taylor & Newell, 2008) is rather subtle, but, in this article, the approximate equality G 0 ∼ G N is simply taken to hold (see the next paragraph for the argument). For these numerical values of the constants η (q 0 ) 3/4 and G 0 , the length scale entering the modified-gravity action term (2.2) has the value L 0 ∼ 10 26 m ∼ 3 Gpc.…”

“…( 2.2) of Klinkhamer (2010a), with q replaced by q 0 and changing the sign in front of the φ R term, where φ ∈ (−∞, 1) is the dimensionless Brans-Dicke scalar field. The corresponding potential U(φ) ∝ η 2 /(1 − φ) is such that it leads to the chameleon effect (Khoury & Weltman, 2004) and the effect is taken to be operative for Cavendishtype experiments on Earth (Cavendish, 1798;Mohr, Taylor & Newell, 2008), giving G 0 ∼ G N (see also Endnote [39] in Klinkhamer (2010a) for further discussion).…”

“…The energy density parameters of (3.6) are defined in terms of the gravitational constant G 0 ≡ G(q 0 ), which may, in principle, be different from Newton's constant G N as measured by laboratory experiments on Earth (Cavendish, 1798;Mohr, Taylor & Newell, 2008). For this reason, the parameters have been denoted by ω and not by the standard symbol Ω.…”

Radiative-nonrecoil corrections of orderα2(Zα)EFto the hyperfine splitting of muonium

“…Therefore, it allows for a very precise test of bound-state QED, and can be used to restrict models of physics beyond the Standard Model. Measurements of the ground-state hyperfine splitting of muonium are used to extract the muon to electron mass ratio m µ /m e and the muon to proton magnetic moment ratio µ µ /µ p [1]. The value of µ µ /µ p is required for obtaining the muon anomalous magnetic moment from experiment [2].…”