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.
118425223
Are there three Xi(1950) states
Different experiments on hadron spectroscopy have long suspected the existence of several cascade states in the $1900-2000 {\rm MeV}$ region. They are usually labeled under the common name of $\Xi (1950)$. As we argue here, there are also theoretical reasons supporting the idea of several $\Xi (1950)$ resonances. In particular, we propose the existence of three $\Xi(1950)$ states: one of these states would be part of a spin-parity $(1/2)^{-}$ decuplet and the other two probably would belong to the $(5/2)^{+}$ and $(5/2)^{-}$ octets. We also identify which decay channels are the more appropriate for the detection of each of the previous states.
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 $J/\psi f_2(1270)$.
62797135
Faddeev fixed center approximation to the $N\bar{K}K$ system and the signature of a $N^*(1920)(1/2^+)$ state
We perform a calculation for the three-body NK-barK scattering amplitude by using the fixed-center approximation to the Faddeev equations, taking the interaction between N and K-bar, N and K, and K-bar and K from the chiral unitary approach. The resonant structures show up in the modulus squared of the three-body scattering amplitude and suggest that a NK-barK hadron state can be formed. Our results are in agreement with others obtained in previous theoretical works, which claim a new N* resonance around 1920 MeV with spin-parity J{sup P}=1/2{sup +}. The existence of these previous works allows us to test the accuracy of the fixed center approximation in the present problem and sets the grounds for possible application in similar problems, as an explorative tool to determine bound or quasibound three-hadron systems.
118784454
Interaction of vector mesons with baryons and vectors in the nuclear medium
In this talk we present a short review of recent developments concerning the interaction of vector mesons with baryons and with nuclei. We begin with the hidden gauge formalism for the interaction of vector mesons, then review results for vector baryon interaction and in particular the resonances which appear as composite states, dynamically generated from the interaction of vector mesons with baryons. New developments concerning the mixing of these states with pseudoscalars and baryons are also reported. We include some discussion on the $5/2^+$ $\Delta$ resonances around 2000 MeV, where we suggest that the $\Delta(2000)5/2^+$ resonance, which comes in the PDG from averaging a set of resonances appearing around 1700 MeV and another one around 2200 MeV, corresponds indeed to two distinct resonances. We also report on a hidden charm baryon state around 4400 MeV coming from the interaction of vector mesons and baryons with charm, and how this state has some repercussion in the $J/\psi$ suppression in nuclei. The interaction of $K^*$ in nuclei is also reported and suggestions are made to measure by means of the transparency ratio the huge width in the medium that the theoretical calculations predict. The formalism is extended to $J/\psi$ interaction with nuclei and the transparency ratio for $J/\psi$ photoproduction in nuclei is studied and shown to be a good tool to find possible baryon states which couple to $J/\psi N$.
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.
118071326
High Performance Photocathodes based on Molecular Beam Epitaxy Deposition for Next Generation Photo Detectors and Light Sources
The development of high-performance photocathodes is a key challenge for future accelerator and particle physics applications. In this paper photocathode growth through molecular beam epitaxy is introduced as a promising technique to obtain robust, highly efficient alkali-antimonide based photocathodes. Recent research shows that the quantum efficiency of photocathodes can be significantly enhanced through control of the photocathode crystallinity. Molecular beam epitaxy allows for cost-effective growth of large-area photocathodes with excellent control of the stoichiometry and crystallinity, making photocathodes with peak quantum efficiencies exceeding 35% routine.
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.
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.
86859005
Instrumentation for Theory-Inspired Photocathode Development within the Large Area Picosecond Photodetector (LAPPD) Project
Abstract We have designed and are commissioning a laboratory for the growth and characterization of photocathodes at Argonne National Laboratory. Two growth facilities, a versatile ultra high vacuum growth chamber and an industrial photomultiplier production facility, allow the investigation of fundamental aspects of the cathode growth and the development, modification and implementation of recipes in an industrial production environment. The instrumentation allows the study of optical properties, electrical behaviors and spectral response of the cathode.