Symmetry-breaking corrections to meson decay constants in the heavy-quark effective theory

Spin- and flavor-symmetry breaking corrections to decay constants of heavy mesons are analyzed in next-to-leading order in the l/m~ expansion. The gen- eral structure of these corrections is derived in an effective-field-theory approach. The subleading universal form factors, which parametrize the matrix elements of higher-dimensional operators in the effective theory, are estimated using QCD sum rules. The renormalization-group improvement of these low-energy parame- ters is discussed in detail. As an application, the spin-symmetry violating effects responsible for the vector-pseudoscalar mass difference and for the ratio of the corresponding decay constants, jv/ jp, are calculated.