Year: 1997
Type: conference-paper
Abstract: which defines the leptonic decay constant, fM . (With this normalisation, fπ ≃ 131MeV.) In (1), Sf is the dressed quark propagator and ΓM(k;P ) is the Bethe-Salpeter amplitude for the bound state; M labels the meson whose flavour content is made explicit by the quark flavour labels, fi. For example, for the B -meson: f1 = u and f2 = b. The calculation of fM requires a knowledge of Sf and ΓM . The dressed-quark propagator has the general form Sf(p) = 1/[iγ · pAf(p) + Bf(p)]: a bare-quark is described by A(p) ≡ 1 and B(p) = m, where m is the current-quark mass. As described in Ref. [1], it is a characteristic of QCD elucidated in Dyson-Schwinger equation studies that for lightquarks; i.e., u-, dand s-quarks, Af (p ) and particularly Bf (p ) have a strong momentumdependence for p < 1GeV. This momentum-dependence is nonperturbative in origin. For the b-quark, however, the momentum-dependence ofAb(p ) andBb(p ) for all spacelikep is weak and mainly perturbative in origin. This suggests that, in phenomenological applications, it is a good approximation to write the dressed-b-quark propagator as
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Award: G1719812184
OpenAlex ID: W1750287109