Very recently it was predicted the existence of a charged state near the $D_sbar{D}^*/D^*_sbar{D}$ threshold. This state, that we call $Z_{cs}^+$, would be the strange partner of the recently observed $Z_c^pm(3900)$. Using standard techniques of QCD
sum rules, we evaluate the three-point function for the vertices $Z_{cs}^+ , J/psi , K^+$, $Z_{cs}^+ , eta_c , K^{*+}$ and $Z_{cs}^+ , D_s^+bar{D}^{*0}$ and we make predictions for the corresponding decay widths in these channels.
Using the Urumqi 25m radio telescope, sources from the first three-month Fermi-LAT detected AGN catalog with declination >0 were observed in 2009 at 4.8 GHz. The radio flux density appears to correlate with the gamma-ray intensity. Intra-day variabil
ity (IDV) observations were performed in March, April and May in 2009 for selected 42 gamma-ray bright blazars, and 60% of them show evident flux variability at 4.8 GHz during the IDV observations, the IDV detection rate is higher than that in previous flat-spectrum AGN samples. The IDV appears more often in the VLBI-core dominant blazars, and the non-IDV blazars show relatively `steeper spectral indices than the IDV blazars. Pronounced inter-month variability has been found in two BL Lac objects: J0112+2244 and J0238+1636.
We study the production of $Z^pm(4430)$ at a nucleon-antinucleon scattering experiment. Considering the PANDA experiment to be an ideal platform to explore the production of the charmonium and charmonim-like states, we suggest the forthcoming PANDA e
xperiment to pay attention to the production of $Z^pm(4430)$.
In this review, we discuss some interesting issues in charm physics which is full with puzzles and challenges. So far in the field there exist many problems which have not obtained satisfactory answers yet and more unexpected phenomena have been obse
rved at the present facilities of high energy physics. Charm physics may become an ideal place for searching new resonances and studying non-perturbative QCD effects, moreover probably is an area to explore new physics beyond the Standard Model. More data will be available at BESIII, B-factories, LHC and even future ILC which may open a wide window to a better understanding of the nature.
It is interesting to search for new physics beyond the standard model at LHCb. We suggest that weak decays of doubly charmed baryon such as $Xi_{cc}(3520)^+, Xi_{cc}^{++}$ to charmless final states would be a possible signal for new physics. In this
work, we consider two models, i.e. the unparticle and $Z$ as examples to study such possibilities. We also discuss the cases for $Xi^0_{bb}, Xi_{bb}^-$ which have not been observed yet, but one can expect to find them when LHCb begins running. Our numerical results show that these two models cannot result in sufficiently large decay widths, therefore if such modes are observed at LHCb, there must be a new physics other than the unparticle or $Z$ models.
Babar Collaboration announced two new excited charmed baryons $Xi_c(3055)^+$ and $Xi_c(3123)^+$. We study their strong decays assuming they are D-wave states. Some assignments are excluded by comparing our numerical results with the experimental valu
es of the total widths of $Xi_c(3055)^+$ and $Xi_c(3123)^+$. We also suggest some possible decay modes, which will be helpful to determine the properties of $Xi_c(3055)^+$ and $Xi_c(3123)^+$.
There has been important experimental progress in the sector of heavy baryons in the past several years. We study the strong decays of the S-wave, P-wave, D-wave and radially excited charmed baryons using the $^3P_0$ model. After comparing the calcul
ated decay pattern and total width with the available data, we discuss the possible internal structure and quantum numbers of those charmed baryons observed recently.
