Search results for "Rule of sum"
showing 5 items of 5 documents
QCD sum rule calculation ofK ℓ3 form factors
1992
We present a combined finite energy sum rule (FESR) and analytic continuation by duality (ACD) calculation of the (neutral)K l3 decay. We confirm the Callan-Treiman relation and investigate the validity of a linear fit for the form factors. Furthermore, we obtain ζ=−0.1...−0.3, consistent with the mean experimental value ζ=−0.1±0.09.
Dipole sum rule enhancement in nuclei
2008
In this work we apply a microscopic many-body approach to photonuclear reactions[1] in order to improve the understanding of the dipole sum rule. At the same time, the sum rule provides us with test of consistency of the underlying theory at low photon energies
Electromagnetic sum rules for light nuclei
2008
Electromagnetic sum rules describe gross features of the electromagnetic structure of nuclei 1). A well known example is the Thomas-Reiche-Kuhn (TRK) sum rule, which relates the integrated total El-absorption cross section to the ground state expectation value of the double commutator of the dipole operator D with the nuclear Hamiltonian. While the k inet ic energy gives a model independent contr ibut ion, i . e . , the classical sum rule ~cl = 60 NZ/A MeV mb, the nuclear twobody potential gives an additional contr ibution in the presence of exchange and/or momentum dependent (or nonlocal) forces. In this case, I
Energy-weighted M1 sum rule with explicit δ degrees of freedom
1985
Abstract The influence of Δ degrees of freedom on the energy-weighted M1 sum rule is investigated and applied to 2 H and 4 He. Using π- and ρ-exchange potentials a reduction of the potential contribution of the order of 50% is obtained. The absolute value of the sum rule is strongly dependent on the short-range behaviour of the nuclear wave function. Furthermore, the contribution of c.m. effects is evaluated and found to be of the order of 5–10%.
A sum rule approach to total muon capture rates
1986
Abstract The total muon capture rate is expanded in terms of sum rules and the convergence of such an expansion is analyzed. It results that the energy-weighted and the inverse-energy-weighted sum rules provide an accurate estimate for the total rate in agreement with a complete RPA calculation through the response function. The static polarizability of the isovector dipole mode turns out to be the relevant quantity to determine the total muon capture rate, in light and medium nuclei.