119232016
Four-quark structure of the excited states of heavy mesons
We propose a four-quark structure for some of the excited states of heavy mesons containing a single charm or bottom quark. The four-quark wave functions are constructed based on a diquark-antidiquark form under the constraint that they form an antitriplet $\bar{\bf{3}}_f$ in $\mbox{SU(3)}_f$, which seems to be realized in some of the excited states listed in Particle Data Group. Depending on the structure of antidiquark, we construct two possible models for its wave functions: Model I) the antidiquark is symmetric in flavor ($\bar{\bf{6}}_f$) and antisymmetric in color ($\bf{3}_c$) and Model II) the antidiquark is antisymmetric in flavor ($\bf{3}_f$) and symmetric in color ($\bar{\bf{6}}_c$). To test phenomenological relevance of these wave functions, we calculate the mass differences among the excited states of spin $J=0,1,2$ using color-spin interactions. The four-quark wave functions based on Model~I is found to reproduce the observed mass of the excited states of heavy mesons. Also, our four-quark model provides an interesting phenomenology relating to the decay widths of the excited states. To further pursue the possibility of the four-quark structure, we make a few predictions for open charm and open bottom states that may be discovered in future experiments. Most of them are expected to have broad widths, which would make them difficult to be identified experimentally. However, one resonance with $J=1$ containing bottom and strange quarks is expected to appear as a sharp peak with its mass around $B^{\bar s}_{1N} \sim 5753$~MeV. Confirmation of the existence of such states in future experiments will shed light on our understanding of the structure of heavy meson excited states.
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.
118886519
Skyrmions with vector mesons in the hidden local symmetry approach
(hWZ) terms. We write a general “master formula” that allows us to determine the parameters of the HLS Lagrangian from a class of holographic QCD models valid at large Nc and � (’t Hooft constant) limit by integrating out the infinite towers of vector and axial-vector mesons other than the lowest � and ! mesons. Within this approach we find that the physical properties of the Skyrmion as the solitonic description of baryons are independent of the HLS parameter a. Therefore the only parameters of the model are the pion decay constant and the vector meson mass. Once determined in the meson sector, we have a totally parameter-free theory that allows us to study unequivocally the role of light vector mesons in the Skyrmion structure. We find, as suggested by Sutcliffe, that
990859
Polarization Observables in {phi} -Meson Photoproduction and the Strangeness Content of the Proton
The contributions of direct knockout processes, in addition to the diffractive production and one-pion-exchange processes associated with the ��� and �� couplings, to the polarization observables of thephotoproduction from pro- ton are calculated. We make use of Pomeron-photon analogy and a relativistic harmonic oscillator quark model. We find that some of the double polariza- tion observables are very sensitive to a possible s¯ s admixture in the proton. It arises from the difference in the spin structures of the three different am- plitudes. This suggests that such measurements could be very useful to probe the strangeness content in the proton.
119182023
Skyrmions, half-skyrmions and nucleon mass in dense baryonic matter
We explore the hadron properties in dense baryonic matter in a unified way by using a Skyrme model constructed with an effective Lagrangian which includes the ρ and ω vector mesons as hidden gauge bosons and is valid up to O(p4) in chiral expansion including the homogeneous Wess-Zumino terms. With the two input values of pion decay constant and the lowest lying vector meson mass which can be fixed in free space, all the other low energy constants in the effective Lagrangian are determined by their master formulas derived from holographic QCD models, which allows us to study the baryonic matter properties with no additional free parameters and thus without ambiguities. We find that the ω field that figures in the homogeneous Wess-Zumino term plays a crucial role in the skyrmion structure and its matter properties. The most striking and intriguing observation is that the pion decay constant that smoothly drops with increasing density in the Skyrmion phase stops decreasing at n1/2 at which the skyrmions in medium fractionize into half-skyrmions and remains nearly constant in the half-skyrmion phase. In accordance with the large Nc consideration, the baryon mass also stays non-scaling in the half-skyrmion phase. This feature is supported by the nuclear effective field theory with the parameters of the Lagrangian scaling modified at the skyrmion–half-skyrmion phase transition. Our exploration also uncovers the crucial role of the ω meson in multi-baryon systems as well as in the structure of a single skyrmion.
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.
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.
121615298
Measurement of the refractive index of the LAB-based liquid scintillator and acrylic at RENO
In this paper, we describe the first measurement of the refractive index of the linear alkyl benzene (LAB)-based liquid scintillator and acrylic used at the Reactor Experiment for Neutrino Oscillation (RENO). The refractive index of a material is an important optical property and the prism spectrometer is the most common device for measuring the refractive index. Using the minimum deviation technique, which requires an exact measurement of the apex angle, we determined the refractive indices at six different wavelengths and then fitted them. We also compared the refractive index of the LAB-based liquid scintillator with the refractive indices of other liquid scintillator solvents commonly used in reactor neutrino experiments.