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We use QCD sum rules to study the recently observed meson $Z^+(4430)$, considered as a $D^*D_1$ molecule with $J^{P}=0^{-}$. We consider the contributions of condensates up to dimension eight and work at leading order in $alpha_s$. We get $m_Z=(4.40pm0.10) GeV$ in a very good agreement with the experimental value. We also make predictions for the analogous mesons $Z_{s}$ and $Z_{bb}$ considered as $D_s^*D_1$ and $B^*B_1$ molecules respectively. For $Z_{s}$ we predict $m_{Z_{s}}= (4.70pm 0.06) {rm GeV}$, which is above the $D_s^*D_1$ threshold, indicating that it is probably a very broad state and, therefore, difficult to be experimentally seen. For $Z_{bb}$ we predict $m_{Z_{bb}}= (10.74pm 0.12) {rm GeV}$, in agreement with quark model predictions.
The pion-baryon sigma terms and the strange-quark condensates of the octet and the decuplet baryons are calculated by employing the method of quantum chromodynamics (QCD) sum rules. We evaluate the vacuum-to-vacuum transition matrix elements of two b
In the present work, the temperature dependence of the scalar mesons parameters is investigated in the framework of thermal QCD sum rules. We calculate sigma-pole and the non-resonant two-pion continuum contributions to the spectral density. Taking i
We evaluate the pion-nucleon and the pion-Delta sigma terms by employing the method of quantum chromodynamics (QCD) sum rules. The obtained value of the pion-nucleon sigma term is compatible with the larger values already anticipated by the recent ca
By using the quark part of the energy-momentum tensor current, the gravitational formfactors of the $ rho $ meson are calculated within the light-cone sum rules method. In the considered version, the energy-momentum tensor current is not conserved an
We test the validity of the QCD sum rules applied to the meson $Z^+(4430)$, by considering a diquark-antidiquark type of current with $J^{P}=0^{-}$ and with $J^{P}=1^{-}$. We find that, with the studied currents, it is possible to find an acceptable