44 research outputs found
The pure annihilation type decays and in perturbative QCD approach
We calculate the branching ratios of pure annihilation type decays
and using
the perturbative QCD approach based on factorization. The branching
ratios are predicted to be for ,
for and for .
They are large enough to be measured in the ongoing experiment. Due to the
shortage of contributions from penguin operators, there are no direct CP
asymmetries for these decays in the standard model. We also derive simple
relations among these decay channels to reduce theoretical uncertainties for
the experiments to test the accuracy of theory and search of new physics
signal.Comment: 9pages, 1 figur
Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay
The decay channel
is studied using a sample of events collected
by the BESIII experiment at BEPCII. A strong enhancement at threshold is
observed in the invariant mass spectrum. The enhancement can be fit
with an -wave Breit-Wigner resonance function with a resulting peak mass of
and a
narrow width that is at the 90% confidence level.
These results are consistent with published BESII results. These mass and width
values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics
Soccer robot path planning based on the artificial potential field approach with simulated annealing
Doubly-heavy baryon weak decays: Ξbc0→pK− and Ξcc+→Σc++(2520)K−
Doubly-heavy baryons, with two heavy and one light quarks, are expected to exist in QCD and their masses have been predicted in the quark model. However their existence is not well established so far in experiment. In this work, we explore the possibility of searching for Ξbc and Ξcc+ in the W-exchange processes, Ξbc0→pK− and Ξcc+→Σc++(2520)K−. On the basis of perturbative calculations, we estimate the branching ratio of the first decay as BR(Ξbc0→p+K−)≈3.21×Rf2×Rτ×10−7, where Rf (Rτ) are the ratios of the decay constants (lifetimes) of Ξbc0 and Λb0. The branching ratio of Ξcc+→Σc++(2520)K− is related to that of Λc+→Δ++K−, and thereby a conjectured topology analysis leads to the range for the branching ratio as: BR(Ξcc+→Σc++(2520)K−)∈[0.36%,1.80%]. The decay Ξcc+→Σc++(2520)K− would be reconstructed in the Λc+K−π+ final state which is easy to access even at a hadron collider. Based on the two facts that abundant heavy quarks can be produced at a hadron collider like LHC, and the branching ratios of Ξbc0→pK− and Ξcc+→Σc++(2520)K− are sizable, we urge our experimental colleagues to perform a search at LHCb. This will presumably lead to the discovery of the Ξbc and Ξcc+, and precision measurements of the branching ratios in the future are helpful to investigate their decay mechanism