m ￣ c and m ￣ b from M B c and improved estimates of f B c and f B c ( 2 S )

摘要

We extract (for the first time) the correlated values of the running massesm￣candm￣bfromMBcusing QCD Laplace sum rules (LSR) within stability criteria where perturbative (PT) expressions at N2LO and non-perturbative (NP) gluon condensates at LO are included. Allowing the values ofm￣c,b(m￣c,b)to move inside the enlarged range of recent estimates from charmonium and bottomium sum rules (Table 1) obtained using similar stability criteria, we deduce:m￣c(m￣c)=1286(16)MeV andm￣b(m￣b)=4202(8)MeV. Combined with previous estimates (Table 2), we deduce a tentative QCD Spectral Sum Rules (QSSR) average:m￣c(m￣c)=1266(6)MeV andm￣b(m￣b)=4197(8)MeV where the errors come from the precise determinations fromJ/ψand ? sum rules. As a result, we present an improved prediction offBc=371(17)MeV and the tentative upper boundfBc(2S)≤139(6)MeV, which are useful for a further analysis ofBc-decays.