# m_c and m_b from M_B_c and improved estimate of f_B_c and f_B_c (2S)

## TL;DR

This paper uses QCD sum rules to extract the charm and bottom quark masses from B_c meson data, providing improved estimates and decay constants relevant for B_c decay studies.

## Contribution

First extraction of correlated m_c and m_b from M_Bc using QCD Laplace sum rules with stability criteria, including perturbative and non-perturbative effects.

## Key findings

- m_c(m_c) = 1286(16) MeV
- m_b(m_b) = 4208(8) MeV
- f_B_c = 371(17) MeV

## Abstract

We extract (for the first time) the correlated values of the running masses m_c and m_b from M_Bc using QCD Laplace sum rules (LSR) within stability criteria where pertubative (PT) expressions at N2LO and non-perturbative (NP) gluon condensates at LO are included. Allowing the values of m_{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, wee deduce : m_c(m_c) = 1286(16) MeV and m_b(m_b) = 4208(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 and m_b(m_b) = 4197(8) MeV, where the errors come from the precise determinations from J/psi and Upsilon sum rules. As a result, we present an improved prediction of f_B_c =371(17)MeV and the tentative upper bound f_B_c(2S)<139(6) MeV, which are useful for a further analysis of B_c-decays.