Msub(s)-Msub(u) quark mass difference and the scalar form factor of Ksub(μ3)0 reaction

We study throudh QCD sum rules the connection between the invariant quark mass difference msub(s)-msub(u) and the scalar form factor of the reaction K0->π-μ+νsub(μ) in the physical region. We use both theoretical information, (the value of fsub(+)(0) and the Callan-Treiman relation, including msub(π)2/msub(k)2 corrections) and experimental one (the value of lambda0 from a linear fit) to give a lower bound for msub(s)-msub(u). Taking the world most recent fitted value for lambda0, lambda0=0.025, which may be reasonably identified with the slope at t=0, and fsub(+)(0)proportional0.98, we obtain msub(s)-msub(u)>=250 MeV for Λsub(MS)=150 MeV. The relevant hypothesis and experimental trends are discussed. (orig.)