118554249
A new perspective on the $\Delta_{5/2^{+}}(2000)$ puzzle
We argue that $\Delta_{5/2^{+}}(2000)(\ast\ast),$ cataloged as a resonance in the Particle Data Book Review (PDG), should be interpreted instead as two distinctive resonances, $\Delta_{5/2^{+}}(\sim1740)$ and $\Delta_{5/2^{+}}(\sim2200)$. Our argument is based on a solution of the $\pi\Delta\rho$ problem in a Fixed Center Approximation (FCA) to the Fadeev equations. $\Delta_{5/2^{+}}(\sim1740)$ can then be interpreted as a $\pi-(\Delta \rho)_{N(1675)}$ bound state. As a corollary $\Delta_{1/2^{+}}(1750)(\ast)$ can be understood as a $\pi N_{1/2^{-}}(1650)$ bound state.
118870069
$\bar{B}^0$ and $\bar{B}^0_s$ decays into $J/\psi$ and $f_0(1370),~f_0(1710),~f_2(1270),~f'_2(1525),~K^*_2(1430)$
We make predictions for the ratios of branching fractions of ${\bar B}^0$ and ${\bar B}^0_s$ decays into $J/\psi$ and the scalar mesons $f_0(1370),~f_0(1710)$ or tensor mesons $f_2(1270),~f'_2(1525),~K^*_2(1430)$. The theoretical approach is based on results of chiral unitary theory where these resonances are shown to be generated from the vector meson-vector meson interaction. Eight independent ratios can be predicted and comparison is made with the recent data on $\bar{B}^0_s$ decay into $J/\psi f'_2(1525)$ versus the $\bar{B}^0_s$ decay into $J/\psi f_2(1270)$.
124596955
Hadron Dynamics with Vector Mesons: Matching Theory and Experiment to Identify New Resonances
In this paper, we discuss the γp → KΣ and γn → KΣ reactions, with a peculiar behavior around the K∗0Λ threshold, due to a 1/2− resonance around 2035 MeV. Similarly, we discuss a BES experiment, J/ψ → ηK∗0K̄∗0 decay, which supports the existence of a new h1 resonance around 1830 MeV that was predicted from the vector–vector interaction. A short discussion is then made about recent advances in the charm and beauty sectors.
119272467
The $\gamma p \to na^{+}_{2}(1320) \to n \rho^0 \pi^+$ reactions within an effective Lagrangian approach
We investigate the tensor meson a(2)(1320) photon-production off proton in the gamma p -> na(2)(+) (1320) and gamma p -> n rho(0)pi(+) reactions within the effective Lagrangian approach and isobar model. For gamma p -> na(2)(+) (1320) reaction, by considering the contributions from only the t-channel pi(+) exchange, we get a fairly good description of the current experimental data for the total cross-section. Based on the theoretical results of the gamma p -> na(2)(+) (1320) reaction, we studied the role of a(2)(1320) meson in the gamma p -> n rho(0)pi(+) reaction, which mainly contributes to the gamma p -> n pi(+)pi(+)pi(-) reaction. The latter reaction has been measured by the CLAS Collaboration at the photon energy E-gamma around 5.1 GeV. For the gamma p -> n rho(0)pi(+) reaction, we pay attention to the low photon energy region where the contribution from a(2)(1320) meson is dominant, while the contribution from the pi(2)(1670) meson could be very small and hence can be neglected. The total cross-sections, invariant mass distribution and the Dalitz plot of gamma p -> n rho(0)pi(+) reaction are shown, which can be tested by future experiments.
118372351
Role of the possible $\Sigma^*(\frac{1}{2}^-)$ state in the $\Lambda p \to \Lambda p \pi^0$ reaction
The $\Lambda p \to \Lambda p \pi^0$ reaction near threshold is studied within an effective Lagrangian method. The production process is described by single-pion and single-kaon exchange. In addition to the role played by the $\Sigma^*(1385)$ resonance of spin-parity $J^P = 3/2^+$, the effects of a newly proposed $\Sigma^*$ ($J^P = 1/2^-$) state with mass and width around $1380$ MeV and $120$ MeV are investigated. We show that our model leads to a good description of the experimental data on the total cross section of the $\Lambda p \to \Lambda p \pi^0$ reaction by including the contributions from the possible $\Sigma^*(\frac{1}{2}^-)$ state. However, the theoretical calculations by considering only the $\Sigma^*(1385)$ resonance fail to reproduce the experimental data, especially for the enhancement close to the reaction threshold. On the other hand, it is found that the single-pion exchange is dominant. Furthermore, we also demonstrate that the angular distributions provide direct information of this reaction, hence could be useful for the investigation of the existence of the $\Sigma^*(\frac{1}{2}^-)$ state and may be tested by future experiments.
118860372
Evidence for a narrow $D_{03}$ state in $K^- p \rightarrow \eta \Lambda$ near threshold
Recently, we reported a theoretical study on the $K^- p \to \eta \Lambda$ reaction near threshold by using an effective Lagrangian approach. It was found that the description of angular distribution data measured by the Crystal Ball Collaboration needs a $D_{03}$ resonance with mass $M=1668.5\pm 0.5$ MeV and total decay width $\Gamma=1.5\pm 0.5$ MeV, which is not the conventional $\Lambda$(1690) or other $\Lambda$ state listed in the Particle Data Group book. In the present work, we study the $\Lambda$ polarization in the $K^- p \to \eta \Lambda$ reaction within the same framework. The results show that the existence of this narrow $D_{03}$ state is also compatible with current $\Lambda$ polarization data and that the more accurate $\Lambda$ polarization data at $P_{K^-}=735$MeV can offer further evidence for the existence of this resonance. Furthermore, the role of the $\Lambda(1690)$ resonance in this reaction is also discussed.
3112937
Free electron laser research in China
China has endeavored in the field of FEL research since the mid-eighties. Compton regime, Raman regime, electromagnetic pumping, Cherenkov FEL, and harmonic generator FEL, etc. based on the RF linac accelerator, induction linac accelerator, pulsed-line accelerator, and storage ring have all been developed. These experimental projects are in various stages of development and are discussed in sequence. Theoretical analysis, numerical simulation and components research related to an FEL also will be mentioned briefly.
55912862
Alkali Antimonide Photocathodes in a Can
The next generation of x-ray light sources will need reliable, high quantum efficiency photocathodes. These cathodes will likely be from the alkali antimonide family, which currently holds the record for highest average current achieved from a photoinjector. In this work, we explore a new option for delivering these cathodes to a machine which requires them: use of sealed commercial vacuum tubes. Several sealed tubes have been introduced into a vacuum system and separated from their housing, exposing the active photocathode on a transport arm suitable for insertion into an injector. The separation was achieved without large loss of QE. These cathodes have been compared to those grown via traditional methods, both in terms of QE and in terms of crystalline structure, and found to be similar.
85558439
Development of an Alkali Transfer Photocathode for Large Area Microchannel Plate-Based Photodetectors
The goal of the Large Area Picosecond Photodetector collaboration is to produce 8-inch by 8-inch microchannel plate-based photodetectors, with fast timing resolution of the order of 1-100 ps and high spatial resolution of 0.1-10 mm. At Argonne, the transfer photocathode process being developed is based on a recipe for manufacturing photomultiplier cathodes. Starting with a commercial PMT fabrication facility, the photocathode recipe and growth system will be scaled up using a custom-built glass vessel to produce transfer photocathodes. This leads to the production of the 8-inch by 8-inch photocathode that will be incorporated with the photodetector assembly system.
4567819
Influence of Growth Method on K3Sb Photocathode Structure and Performance
A combination of material science techniques is used to determine the influence of the growth parameters on structure and performance of photocathode materials. In-situ x-ray diffraction (XRD) and in-situ grazing incidence small angle x-ray scattering (GiSAXS), as well as after growth xray reflectivity (XRR) and�/2� - XRD measurements were performed at synchrotron radiation sources. K3Sb is a precursor material for the preparation of CsK2Sb and Na2KSb. The materials growth was studied intensively to optimize this intermediate growth step in terms of quantum efficiency and roughness. The results of two growth methods, a “layer by layer” type and a “super-lattice type”, are presented, as well as the interaction of the K3Sb phase with Cesium.