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.
118615785
Dense baryonic matter in conformally-compensated hidden local symmetry: Vector manifestation and chiral symmetry restoration
We find that, when the dilaton is implemented as a (pseudo-)Nambu-Goldstone boson using a conformal compensator or "conformon" in a hidden gauge symmetric Lagrangian written to $O(p^4)$ from which baryons arise as solitons, namely, skyrmions, the vector manifestation and chiral symmetry restoration at high density predicted in hidden local symmetry theory --- which is consistent with Brown-Rho scaling --- are lost or sent to infinite density. It is shown that they can be restored if in medium the behavior of the $\omega$ field is taken to deviate from that of the $\rho$ meson in such a way that the flavor $U(2)$ symmetry is strongly broken at increasing density. The hitherto unexposed crucial role of the $\omega$ meson in the structure of elementary baryon and multibaryon systems is uncovered in this work. In the state of half-skyrmions to which the skyrmions transform at a density $n_{1/2}^{} \gtrsim n_0^{}$ (where $n_0^{}$ is the normal nuclear matter density), characterized by the vanishing (space averaged) quark condensate but nonzero pion decay constant, the nucleon mass remains more or less constant at a value $\gtrsim$ 60 \% of the vacuum value indicating a large component of the nucleon mass that is not associated with the spontaneous breaking of chiral symmetry. We discuss its connection to the chiral-invariant mass $m_0^{}$ that figures in the parity-doublet baryon model.
55817266
Medium modifications of the {rho} meson in nuclear photoproduction.
We extend our recent study of dilepton invariant-mass spectra from the decays of {rho} mesons produced by photon reactions off nuclei. We specifically focus on experimental spectra as recently measured by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility using carbon and iron nuclei. Building on our earlier work, we broaden our description to a larger set of observables to identify sensitivities to the medium effects predicted by microscopic calculations of the {rho} spectral function. We compute mass spectra for several target nuclei and study the spectral shape as a function of the three-momentum of the outgoing lepton pair. We also compute the so-called nuclear transparency ratio, which provides an alternative means (and thus consistency check) of estimating the {rho} width in the cold nuclear medium.
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
119373001
Form-factor dependence of the J/psi dissociation cross sections in meson exchange model
The $J/\psi$ dissociation by $\pi$ and $\rho$ mesons is examined in meson exchange model and compared to the quark interchange model. We found that the main difference between the predictions of the two models could be resolved by the form factors and the contact interactions in meson exchange model calculations. By adopting covariant form factors and adjusting the four-point couplings, we found that the meson exchange model could give similar predictions with the quark interchange models not only for the magnitudes but also for the energy dependence of the low-energy dissociation cross sections of the $J/\psi$ by $\pi$ and $\rho$ mesons. Our finding suggests a way to understand one of the discrepancies among the existing model predictions on the $J/\psi$ dissociation cross sections by light hadrons.
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.
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.