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Qun Wang

Publications and source records attributed to Qun Wang.

203 records · Page 12Linked to original sources
arXiv2000

Color separate singlets in $e^+e^-$ annihilation

We use the method of color effective Hamiltonian to study the properties of states in which a gluonic subsystem forms a color singlet, and we will study the possibility that such a subsystem hadronizes as a separate unit. A parton system can normally be subdivided into singlet subsystems in many different ways, and one problem arises from the fact that the corresponding states are not orthogonal. We show that if only contributions of order $1/N_c^2$ are included, the problem is greatly simplified. Only a very limited number of states are possible, and we present an orthogonalization procedure for these states. The result is simple and intuitive and could give an estimate of the possibility to produce color separated gluonic subsystems, if no dynamical effects are important. We also study with a simple MC the possibility that configurations which correspond to "short strings" are dynamically favored. The advantage of our approach over more elaborate models is its simplicity, which makes it easier to estimate color reconnection effects in reactions which are more complicated than the relatively simple $e^+e^-$ annihilation.

hep-ph↗
arXiv1999

$e^{+}e^{-}\to Z^0Z^0\to b\bar{b}c\bar{c}$ events as model independent probe of colour reconnection effects

According to the basic properties of QCD, colour reconnection effects can occur in hadronic processes at high energies. The comparison of $e^{+}e^{-}\to Z^0Z^0\to q\bar{q}q'\bar{q'}$ events with the superposition of $Z^0\to q\bar{q}$ and $Z^0\to q'\bar{q'}$ events from LEP1 would provide an unambiguous model-independent probe. We show that at LEP2 energy, the background processes are negligible if we select only $e^{+}e^{-}\to Z^0Z^0\to b \bar{b}c\bar{c}$ events, and limit the measurements in the phase space of on-shell $Z^0Z^0$ events.

hep-ph↗
arXiv1999

Contribution of Colour-singlet Process $Υ\to J/Ψ+ c\bar{c}g$ to $Υ\to J/Ψ+ X$

We show that the colour-singlet process $Υ\to J/Ψ+ c\bar{c}g$ significantly contributes to the inclusive process $Υ\to J/Ψ+ X$. We calculate the partial width and the momentum distribution of the produced $J/Ψ$ in this channel. The obtained width is comparable to the experimental data. The momentum distribution is fairly soft, which is in contrast to the results from the colour-octet processes discussed earlier in literature but is consistent with the CLEO measurements. Further experiments to check this contribution are suggested.

hep-ph↗
arXiv1997

Probability of Color Rearrangement at Partonic Level in Hadronic W^+W^- Decays

A strict method to calculate the color rearrangement probability at partonic level in hadronic $W^+W^-$ decays is proposed. The color effective Hamiltonian $H_c$ is constructed from invariant amplitude for the process $e^+e^- \to W^+W^- \to q_1\bar{q}_2 q_3\bar{q}_4+ng$ (n=0, 1, 2, ...) and is used to calculate the cross sections of various color singlets and the color rearrangement probability. The true meaning of the color rearrangement is clarified and its difference from color interference is discussed.

hep-ph↗