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Register a new user$gamma^* N rightarrow Delta^{+}(1600)$ transition form factors in light-cone sum rules
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The form factors of $gamma^* N rightarrow Delta(1600)$ transition is calculated within the light-cone sum rules assuming that $Delta^+(1600)$ is the first radial excitation of $Delta(1232)$. The $Q^2$ dependence of the magnetic dipole $tilde{G}_M(Q^2)$, electric quadrupole $tilde{G}_E(Q^2)$, and Coulomb quadrupole $tilde{G}_c(Q^2)$ form factors are investigated. Moreover, the $Q^2$ dependence of the ratios $R_{EM} = -frac{tilde{G}_E(Q^2)}{tilde{G}_M{Q^2}}$ and $R_{SM} = - frac{1}{4 m_{Delta(1600)}^2} sqrt{4 m_{Delta(1600)}^2 Q^2 + (m_{Delta(1600)}^2 - Q^2 - m_N^2)^2} frac{tilde{G}_c(Q^2)}{tilde{G}_M(Q^2)}$ are studied. Finally, our predictions on $tilde{G}_M(Q^2)$, $tilde{G}_E(Q^2)$, and $tilde{G}_C(Q^2)$ are compared with the results of other theoretical approaches.
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We present a new calculation of the semileptonic tree-level and flavor-changing neutral current form factors describing $B$-meson transitions to tensor mesons $T=D_2^*,K_2^*,a_2,f_2$ ($J^{P}=2^{+}$). We employ the QCD Light-Cone Sum Rules approach with $B$-meson distribution amplitudes. We go beyond the leading-twist accuracy and provide analytically, for the first time, higher-twist corrections for the two-particle contributions up to twist four terms. We observe that the impact of higher twist terms to the sum rules is noticeable. We study the phenomenological implications of our results on the radiative ${B} to K_2^{*}gamma$ and semileptonic ${B} to D_2^* ell {bar u}_ell$, ${B} to K_2^{*}ell^+ell^-$ decays.
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We derive new QCD sum rules for $Bto D$ and $Bto D^*$ form factors. The underlying correlation functions are expanded near the light-cone in terms of $B$-meson distribution amplitudes defined in HQET, whereas the $c$-quark mass is kept finite. The leading-order contributions of two- and three-particle distribution amplitudes are taken into account. From the resulting light-cone sum rules we calculate all $Bto Dst $ form factors in the region of small momentum transfer (maximal recoil). In the infinite heavy-quark mass limit the sum rules reduce to a single expression for the Isgur-Wise function. We compare our predictions with the form factors extracted from experimental $Bto Dst l u_l$ decay rates fitted to dispersive parameterizations.
We study the electromagnetic nucleon form factors within the approach based on light-cone sum rules. We include the next-to-leading-order corrections for the contributions of twist-three and twist-four operators and a consistent treatment of the nucleon mass corrections in our calculation. It turns out that a self-consistent picture arises when the three valence quarks carry $40%:30%:30%$ of the proton momentum.
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