41744701
Nuclear modification factor of nonphotonic electrons in heavy-ion collisions, and the heavy-flavor baryon-to-meson ratio
The nuclear modification factor ${R}_{\mathit{AA}}$ of nonphotonic electrons in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{\mathit{NN}}}=200$ GeV is studied by considering the decays of heavy-flavor hadrons produced in a quark coalescence model. Although an enhanced ${\ensuremath{\Lambda}}_{c}/{D}^{0}$ ratio is predicted by the coalescence model, it is peaked at small transverse momenta ($~2$ GeV) due to the large difference between heavy and light quark masses. As a result, the enhanced ${\ensuremath{\Lambda}}_{c}/{D}^{0}$ ratio, which is expected to suppress the electron ${R}_{\mathit{AA}}$ as the branching ratio of ${\ensuremath{\Lambda}}_{c}$ decay into electrons is smaller than that of ${D}^{0}$, does not lead to additional suppression of the electron ${R}_{\mathit{AA}}$ at large transverse momenta ($\ensuremath{\geqslant}5$ GeV), where the suppression is mainly due to heavy quark energy loss in produced quark-gluon plasma. Also, the enhanced ${\ensuremath{\Lambda}}_{b}/{\overline{B}}^{0}$ ratio predicted by the coalescence model has even smaller effect on the nonphotonic electron ${R}_{\mathit{AA}}$ as bottom baryons and mesons have similar branching ratios for semileptonic decays into electrons.
34315779
Heavy quark symmetry and the Skyrme model.
We present a consistent way of describing heavy baryons containing a heavy quark as bound states of an SU(2) soliton and heavy mesons. The resulting mass formula reveals the heavy quark symmetry explicitly. By extending the model to the orbitally excited states, we establish the generic structure of the heavy baryon spectrum. As anticipated from the heavy quark spin symmetry, the [ital c] factor denoting the hyperfine splitting constant [ital vanishes] and the baryons with the same angular momentum of light degrees of freedom form degenerate doublets. This approach is also applied to the pentaquark exotic baryons, where the conventional [ital c] factor no longer plays the role of the hyperfine constant. After diagonalizing the Hamiltonian of order [ital N][sub [ital c]][sup [minus]1], we get the degenerate doublets, which implies the vanishing of genuine hyperfine splitting.
118186466
Higher meson resonances in rho ---> pi0 pi0 gamma and omega ---> pi0 pi0 gamma
The role of higher meson resonances with spin 1 and 2 is investigated quantitatively in the decay processes of $\rho \to \pi^0\pi^0 \gamma$ and $\omega \to \pi^0 \pi^0 \gamma$. Among the higher resonances, we find that the $f_2(1270)$ tensor meson can give a nontrivial contribution especially to the $\omega \to \pi^0 \pi^0 \gamma$ decay process. When the $f_2$ contribution is combined with the processes involving the vector and scalar meson intermediate states, a good agreement with the recent measurements is achieved for both decays. The effect of the $f_2(1270)$ is found to be sizable at the intermediate photon energies and may be verified by precise measurements of the recoil photon spectrum of the $\omega \to \pi^0 \pi^0 \gamma$ decay. The dependence of the decay widths on various models for the $\rho$-$\omega$ mixing in the literature is also investigated.
118870815
Phi-meson photoproduction and strangeness of the nucleon
The polarization observables in phi photoproduction are suggested for probing the nucleon strangeness. Based on models for phi photoproduction, some double polarization observables are shown to be very sensitive to the strangeness content of the proton because of the different spin structures of the amplitudes associated with different mechanisms.
118406380
Photoproduction of K Sigma(1385) from the nucleon
The reactions of $K \Sigma(1385)$ photoproduction, i.e., $\gamma p \to K^+ \Sigma^0(1385)$ and $\gamma n \to K^+ \Sigma^-(1385)$, are investigated in the resonance energy region for studying the role of the nucleon and $\Delta$ resonances of masses around 2 GeV. The Lagrangians for describing the decays of these resonances into the $K \Sigma(1385)$ channel are constructed and the decay amplitudes are obtained, which allows us to determine the coupling constants using the predictions of quark models or the data listed by the Particle Data Group. The resulting cross sections are compared to the data from the Thomas Jefferson National Accelerator Facility and the SPring-8, which indicates nontrivial contributions from the two-star-rated resonances in the Particle Data Group as well as from some missing resonances predicted by a quark model.
34948294
Heavy baryons as Skyrmions with 1/mQ corrections.
We take into account the 1/[ital m][sub [ital Q]] corrections up to 1/[ital N][sub [ital c]] order in the heavy-meson-soliton bound state approach for heavy baryons. With these corrections, the mass spectra of baryons with [ital c] quarks as well as of those with [ital b] quarks are well reproduced. For charmed baryons, however, the correction to the mass spectra amounts to about 300 MeV, which is not small compared to the leading order binding energy, [similar to]800 MeV.
120748606
Current status of RENO
We report the current status of Reactor Experiment for Neutrino Oscillation(RENO), which is located on the site of Yonggwang nuclear power plant in the southwestern part of Korea. Two identical detectors are being constructed at 290m and 1380m from the reactor cores, and mockup detector is built to study many technical questions of liquid scintillator and main detectors.
121196804
CERN beam test of silicon-tungsten calorimeter test module
PIN diode silicon sensors with low leakage current were developed as 4×4 pixel arrays from 5 inch wafers. A test module of silicon-tungsten calorimeter was designed, built using the sensors, and tested with high energy beam of electron, muon, and hadrons for the study of its application at the future linear collider. The construction of the test module and the results of the beam test are discussed.