DJpsiFDC: an event generator for the process gg→J/ψJ/ψgg\to J/\psi J/\psi at LHC

DJpsiFDC is an event generator package for the process $gg\to J/\psi J/\psi$. It generates events for primary leading-order $2\to 2$ processes. The package could generate a LHE document and this document could easily be embedded into detector simulation software frameworks. The package is produced in Fortran codes.Comment: 10 pages, 3 figure

Estimating the mass of the hidden charm 1+(1+)1^+(1^{+}) tetraquark state via QCD sum rules

By using QCD sum rules, the mass of the hidden charm tetraquark $[cu][\bar{c}\bar{d}]$ state with $I^{G} (J^{P}) = 1^+ (1^{+})$ (HCTV) is estimated, which presumably will turn out to be the newly observed charmonium-like resonance $Z_c^+(3900)$. In the calculation, contributions up to dimension eight in the operator product expansion(OPE) are taken into account. We find $m_{1^+}^c = (3912^{+306}_{-153}) \, \text{MeV}$, which is consistent, within the errors, with the experimental observation of $Z_c^+(3900)$. Extending to the b-quark sector, $m_{1^+}^b = (10561^{+395}_{-163}) \,\text{MeV}$ is obtained. The calculational result strongly supports the tetraquark picture for the "exotic" states of $Z_c^+(3900)$ and $Z_b^+(10610)$.Comment: 13 pages,3 figures, 1 table, version to appear in EPJ

Molecular states with hidden charm and strange in QCD Sum Rules

This work uses the QCD Sum Rules to study the masses of the $D_s \bar{D}_s^*$ and $D_s^* \bar{D}_s^*$ molecular states with quantum numbers $J^{PC} = 1^{+-}$. Interpolating currents with definite C-parity are employed, and the contributions up to dimension eight in the Operator Product Expansion (OPE) are taken into account. The results indicate that two hidden strange charmonium-like states may exist in the energy ranges of $3.83 \sim 4.13$ GeV and $4.22 \sim 4.54$ GeV, respectively. The hidden strange charmonium-like states predicted in this work may be accessible in future experiments, e.g. BESIII, BelleII and SuperB. Possible decay modes, which may be useful in further research, are predicted.Comment: 15 pages, 6 figures, 2 tables, to appear in EP

Reformulating the Quantum Uncertainty Relation

Uncertainty principle is one of the cornerstones of quantum theory. In the literature, there are two types of uncertainty relations, the operator form concerning the variances of physical observables and the entropy form related to entropic quantities. Both these forms are inequalities involving pairwise observables, and are found to be nontrivial to incorporate multiple observables. In this work we introduce a new form of uncertainty relation which may give out complete trade-off relations for variances of observables in pure and mixed quantum systems. Unlike the prevailing uncertainty relations, which are either quantum state dependent or not directly measurable, our bounds for variances of observables are quantum state independent and immune from the "triviality" problem of having zero expectation values. Furthermore, the new uncertainty relation may provide a geometric explanation for the reason why there are limitations on the simultaneous determination of different observables in $N$-dimensional Hilbert space.Comment: 15 pages, 2 figures; published in Scientific Report

QCD Pomeron at Linear Colliders

Recent developments in theory on the calculation of \gamma^* \gamma^* reaction at high energies, in the aim of detecting the BFKL Pomeron signals, are briefly introduced. The importance of the NLO QCD corrections to the Photon Impact Factor in the game is highlighted.Comment: Contribution to LCWS2000, Fermilab, 24-28 October, 2000, typos in the references correcte