Hadronic Decays Involving Heavy Pentaquarks

Recently several experiments have reported evidences for pentaquark $\Theta^+$. H1 experiment at HERA-B has also reported evidence for $\Theta_c$. $\Theta^+$ is interpreted as a bound state of an $\bar s$ with other four light quarks $udud$ which is a member of the anti-decuplet under flavor $SU(3)_f$. While $\Theta_c$ is a state by replacing the $\bar s$ in $\Theta^+$ by a $\bar c$. One can also form $\Theta_b$ by replacing the $\bar s$ by a $\bar b$. The charmed and bottomed heavy pentaquarks form triplets and anti-sixtets under $SU(3)_f$. We study decay processes involving at least one heavy pentaquark using $SU(3)_f$ and estimate the decay widths for some decay modes. We find several relations for heavy pentaquarks decay into another heavy pentaquark and a $B (B^*)$ or a $D(D^*)$ which can be tested in the future. $B$ can decay through weak interaction to charmed heavy pentaquarks. We also study some $B$ decay modes with a heavy pebtaquark in the final states. Experiments at the current $B$ factories can provide important information about the heavy pentaquark properties.Comment: RevTex 20 pages. Revised version. Discussions on the recent H1 data and new references adde

Coordinating tasks in M-form and U-form organisations

We model the coordination of specialised tasks inside an organisation as "attribute matching". Using this method, we compare the performance of organisational forms (M-form and U-form) in implementing changes such as innovation and reform. In our framework, organisational forms affect the information structure of an organisation and thus the way to coordinate changes. Compared to the U-form, the M-form organisation achieves better coordination but suffers from fewer economies of scale. The distinctive advantage of the M-form is flexibility of experimentation, which allows the organisation to introduce more innovation and reform. The theory is illustrated by the organisational differences between China and the former Soviet Union and sheds light on their different reform strategies, particularly with regard to the prevalence of the experimental approach in China

Probing scalar meson structures in χc1\chi_{c1} decays into pseudoscalar and scalar

We evaluate the decay branching ratios of $\chi_{c1}\to PS$, in a quark model parametrization scheme, where $P$ and $S$ stand for pseudoscalar and scalar meson, respectively. An interesting feature of this decay process is that the $c\bar{c}$ annihilate via the pQCD hair-pin diagram is supposed to be dominant. Hence, this decay process should be sensitive to the quark components of the final-state light mesons, and would provide a great opportunity for testing the mixing relations among the scalar mesons, i.e. $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$, by tagging the final state pseudoscalar mesons.Comment: 9 pages and 6 eps figures; Enhanced discussion on the dominance of hair-pin diagram is added. Revised version to appear in IJMP

Probing the nature of Y(4260)Y(4260) and Zc(3900)Z_c(3900) in the isospin violating process Y(4260)→J/ψηπ0Y(4260) \to J/\psi \eta \pi^0

The isospin violation process $Y(4260) \to J/\psi \eta \pi^{0}$ is studied assuming that $Y(4260)$ is a $D_{1} \bar{D}+c.c.$ hadronic molecule. In association with the production of the $Z_c(3900)$, which is treated as a $D \bar{D}^{*}+c.c.$ hadronic molecule, this process can help us distinguish their molecular natures from other scenarios, since the incomplete cancellation between the charged and neutral--meson loops, which are prominent in the molecular picture only, produces a peak in the $e^+e^-\to Y(4260)\to J/\psi\eta\pi^0$ cross section at the $D_{1} \bar{D}+c.c.$ threshold and a very prominent peak in the $J/\psi \eta$ invariant mass spectrum in between the $D \bar{D}^{*}+c.c.$ thresholds; the latter being much narrower than the corresponding one in the isospin conserving channel, i.e. $J/\psi \pi^+ \pi^{-}$. The partial width of $Y(4260)\to J/\psi\eta\pi^0$ is about $4 \times 10^{-4}$ of that of $Y(4260)\to J/\psi\pi^+\pi^-$. The cross section of $e^+e^-\to Y(4260)\to J/\psi\eta\pi^0$ at the $D_{1} \bar{D}+c.c.$ threshold is about $0.05 \ \mathrm{pb}$ which is much larger than that produced by the nearby resonances. These features are the direct consequences of the assumed nature of these two states which might be accessible at the high-statistics experiments such as BESIII and LHCb.Comment: 11 pages, 4 figure

Further understanding of the non-DDˉD\bar D decays of ψ(3770)\psi(3770)

We provide details of the study of $\psi(3770)$ non-$D\bar D$ decays into $VP$, where $V$ and $P$ denote light vector meson and pseudoscalar meson, respectively. We find that the electromagnetic (EM) interaction plays little role in these processes, while the strong interaction dominates. The strong interaction can be separated into two parts, i.e. the short-distance part probing the wave function at origin and the long-distance part reflecting the soft gluon exchanged dynamics. The long-distance part is thus described by the intermediate charmed meson loops. We show that the transition of $\psi(3770)\to VP$ can be related to $\psi(3686)\to VP$ such that the parameters in our model can be constrained by comparing the different parts in $\psi(3770)\to VP$ to those in $\psi(3686)\to VP$. Our quantitative results confirm the findings of [Zhang {\it et al.}, Phys. Rev. Lett. 102, 172001 (2009)] that the OZI-rule-evading long-distance strong interaction via the IML plays an important role in $\psi(3770)$ decays, and could be a key towards a full understanding of the mysterious $\psi(3770)$ non-$D\bar{D}$ decay mechanism.Comment: 11 pages, 4 figures, version to appear in Phys. Rev.