Understanding the internal structures of the X(4140)X(4140), X(4274)X(4274), X(4500)X(4500) and X(4700)X(4700)

We investigate the newly observed $X(4500)$ and $X(4700)$ based on the diquark-antidiquark configuration within the framework of QCD sum rules. Both of them may be interpreted as the $D$-wave $cs\bar{c}\bar{s}$ tetraquark states of $J^P = 0^+$, but with opposite color structures, which is remarkably similar to the result obtained in Ref.~\cite{Chen:2010ze} that the $X(4140)$ and $X(4274)$ can be both interpreted as the $S$-wave $cs\bar{c}\bar{s}$ tetraquark states of $J^P = 1^+$, also with opposite color structures. However, the extracted masses and these suggested assignments to these $X$ states do depend on these running quark masses where m_s (2 \mbox{ GeV}) = 95 \pm 5 MeV and $m_c (m_c) = 1.23 \pm 0.09$ GeV. As a byproduct, the masses of the hidden-bottom partner states of the $X(4500)$ and $X(4700)$ are extracted to be both around 10.64 GeV, which can be searched for in the $\Upsilon \phi$ invariant mass distribution.Comment: 6 pages, 4 figures. Accepted by Eur. Phys. J.

New molecular candidates: X(1910), X(2200), and X(2350)

Assuming the newly observed resonant structures X(1910), X(2200), and X(2350) as $\omega\omega$, $\omega\phi$, and $\phi\phi$ molecular states respectively, we compute their mass values in the framework of QCD sum rules. The numerical results are $1.97\pm0.17 {GeV}$ for $\omega\omega$ state, $2.07\pm0.21 {GeV}$ for $\omega\phi$ state, and $2.18\pm0.29 {GeV}$ for $\phi\phi$ state, which coincide with the experimental values of X(1910), X(2200), and X(2350), respectively. This supports the statement that X(1910), X(2200), and X(2350) could be $\omega\omega$, $\omega\phi$, and $\phi\phi$ molecular candidates respectively.Comment: 9 pages, 9 eps figures; the name of X(2000) changed to X(1910) according to the updated data of experiments; more references and discussions added; accepted for publication in PRD. arXiv admin note: substantial text overlap with arXiv:1211.2277, arXiv:1201.341

Superparamagnetic relaxation in Cu_{x}Fe_{3-x}O_{4} (x=0.5 and x=1) nanoparticles

The scope of this article is to report very detailed results of the measurements of magnetic relaxation phenomena in the new Cu$_{0.5}$Fe$_{2.5}$O$_{4}$ nanoparticles and known CuFe$_{2}$O$_{4}$ nanoparticles. The size of synthesized particles is (6.5$\pm$1.5)nm. Both samples show the superparamagnetic behaviour, with the well-defined phenomena of blocking of magnetic moment. This includes the splitting of zero-field-cooled and field-cooled magnetic moment curves, dynamical hysteresis, slow quasi-logarithmic relaxation of magnetic moment below blocking temperature. The scaling of the magnetic moment relaxation data at different temperatures confirms the applicability of the simple thermal relaxation model. The two copper-ferrites with similar structures show significantly different magnetic anisotropy density and other magnetic properties. Investigated systems exhibit the consistency of all obtained results.Comment: 18 pages, 8 figure