67764301
Study of an avalanche-mode resistive plate chamber
Resistive plate chambers (RPCs) are widely used to detect high-energy charged particles, especially muons, due to the high gain, moderate time and spatial resolution, simple design and low cost of these detectors. While the simple streamer mode is adequate for cosmic-ray and low-rate accelerator experiments, the avalanche mode is required for high-rate experiments such as CMS at LHC. In this paper construction of a medium-sized double-gap RPC made of Chinese materials is reported. The experimental set-up of cosmic-ray and muon beam tests are introduced. The avalanche mode was clearly observed. Good efficiency and time resolution were obtained from the beam test at CERN under normal irradiation conditions. At very high radiation background the chamber efficiency decreases, indicating the necessity to change the resistivity value of the Chinese bakelites.
120951655
FLAT CONNECTIONS ON QUANTUM BUNDLES AND FRACTIONAL STATISTICS IN GEOMETRIC-QUANTIZATION
It is shown that in geometric quantization formulation, fractional statistics in a quantized system of N indistinguishable particles in two spatial dimensions arise from the nontrivial cohomology of the flat connection on the quantum line bundles as well as from the nontrivial homology of the configuration space. The propagator of a nonrelativistic interacting system with fractional statistics is derived.
118501315
The bethe-salpeter wave functions of the free fermion-antifermion system with O-+, 1--, 1+-, 0++ and 1++
SummaryWe derived the Bethe-Salpeter wave functions of a free fermion-antifermion system with JPC = 0-+, 1--, l+-, 0++ and 1++.RiassuntoSi derivano le funzioni d’onda di Betlie-Salpeter di un sistema libero fermione-antifermione con JPC = 0-+, 1--, 1+-, 0++ e 1++.РЕжУМЕМы ВыВОДИМ ВОлНОВыЕ Ф УНкцИИ БЕтЕ-сАлпИтЕР А Дль сВОБОДНОИ ФЕРМИОН-АНтИФЕРМИОН НОИ сИстЕМы с JPC= 0-+, 1--, 1+-, 0++ И 1++.
124965502
The Geometrical Structure of Hamiltonian Systems with the Second Class Constraints
The geometrical structure of a classical Hamiltonian system with Dirac second class constraints is examined. It is shown that for the real physical system, as the submanifold of the original manifold, we may redefine the symplectic form and/or Hamiltonian vector fields to get consistent geometrical descriptions.
125027606
GENERAL-SOLUTIONS OF WESS-ZUMINO CONSISTENCY CONDITIONS FOR AXIAL-VECTOR CURRENT DIVERGENCE ANOMALY
The general solutions of the Wess-Zumino Consistency conditions for axial-vector current divergence anomaly are derived. The terms different from the Bardeen's anomaly in the solutions can be eliminated by using suitable counter terms which do not violate the vector-current conservation. Thus, the Wess-Zumino conditions can be considered to be necessary and sufficient for determining the structure of the minimal consistency axial anomaly up to a multiplicative constant factor.
121486574
Ordering problem in geometrical quantization
The operator ordering problem is investigated in the framework of geometrical quantization in the Schrodinger coordinate representation. It is shown that, for quantization of polarization-preserving classical observables pf(q), correct Hermitian quantum operators are derived; for quantization of polarization-unpreserving classical observables p2f(q), the BKS kernel method actually defines an ordering rule which is not Weyl's rule, but is the GCT-invariant rule proposed by DeWitt (1957).
32132565
Source-plane Reconstruction of the Giant Gravitational Arc in A2667: A Candidate Wolf-Rayet Galaxy at z ~ 1
We present a new analysis of Hubble Space Telescope, Spitzer Space Telescope, and Very Large Telescope imaging and spectroscopic data of a bright lensed galaxy at z = 1.0334 in the lensing cluster A2667. Using this high-resolution imaging, we present an updated lens model that allows us to fully understand the lensing geometry and reconstruct the lensed galaxy in the source plane. This giant arc gives a unique opportunity to view the structure of a high-redshift disk galaxy. We find that the lensed galaxy of A2667 is a typical spiral galaxy with a morphology similar to the structure of its counterparts at higher redshift, z ~ 2. The surface brightness of the reconstructed source galaxy in the z 850 band reveals the central surface brightness I(0) = 20.28 ± 0.22 mag arcsec–2 and a characteristic radius rs = 2.01 ± 0.16 kpc at redshift z ~ 1. The morphological reconstruction in different bands shows obvious negative radial color gradients for this galaxy. Moreover, the redder central bulge tends to contain a metal-rich stellar population, rather than being heavily reddened by dust due to high and patchy obscuration. We analyze the VIMOS/integral field unit spectroscopic data and find that, in the given wavelength range (~1800-3200 A), the combined arc spectrum of the source galaxy is characterized by a strong continuum emission with strong UV absorption lines (Fe II and Mg II) and shows the features of a typical starburst Wolf-Rayet galaxy, NGC 5253. More specifically, we have measured the equivalent widths of Fe II and Mg II lines in the A2667 spectrum, and obtained similar values for the same wavelength interval of the NGC 5253 spectrum. Marginal evidence for [C III] 1909 emission at the edge of the grism range further confirms our expectation.
118606470
Constraints on a phiCDM model from strong gravitational lensing and updated Hubble parameter measurements
We constrain the scalar field dark energy model with an inverse power-law potential, i.e., V()  −α (α > 0), from a set of recent cosmological observations by compiling an updated sample of Hubble parameter measurements including 30 independent data points. Our results show that the constraining power of the updated sample of H(z) data with the HST prior on H0 is stronger than those of the SCP Union2 and Union2.1 compilations. A recent sample of strong gravitational lensing systems is also adopted to confine the model even though the results are not significant. A joint analysis of the strong gravitational lensing data with the more restrictive updated Hubble parameter measurements and the Type Ia supernovae data from SCP Union2 indicates that the recent observations still can not distinguish whether dark energy is a time-independent cosmological constant or a time-varying dynamical component.
119280925
General treatment for dark energy thermodynamics
In this work we discuss a general approach for the dark energy thermodynamics considering a varying equation of state parameter of the type $\ensuremath{\omega}(a)={\ensuremath{\omega}}_{0}+F(a)$ and taking into account the role of a nonzero chemical potential $\ensuremath{\mu}$. We derive generalized expressions for the entropy density, chemical potential, and dark energy temperature $T$ and use the positiveness of the entropy to impose thermodynamic bounds on the equation of state parameter $\ensuremath{\omega}(a)$. In particular, we find that a phantomlike behavior $\ensuremath{\omega}(a)l\ensuremath{-}1$ is allowed only when the chemical potential is a negative quantity ($\ensuremath{\mu}l0$).
119109342
Constraints on the exponential $f(R)$ model from latest Hubble parameter measurements
We investigate the viable exponential $f(R)$ gravity in the metric formalism with $f(R)=-\beta R_s (1-e^{-R/R_s})$. The latest sample of the Hubble parameter measurements with 23 data points is used to place bounds on this $f(R)$ model. A joint analysis is also performed with the luminosity distances of Type Ia supernovae and baryon acoustic oscillations in the clustering of galaxies, and the shift parameters from the cosmic microwave background measurements, which leads to $0.240 1.47$ at 1$\sigma$ confidence level. The evolutions of the deceleration parameter $q(z)$ and the effective equations of state $\omega_{de}^{eff}(z)$ and $\omega_{tot}^{eff}(z)$ are displayed. By taking the best-fit parameters as prior values, we work out the transition redshift (deceleration/acceleration) $z_T$ to be about 0.77. It turns out that the recent observations are still unable to distinguish the background dynamics in the $\Lambda$CDM and exponential $f(R)$ models.