Analysis of resonance multipoles from polarization observables in eta photoproduction

A combined analysis of new eta photoproduction data for total and differential cross sections, target asymmetry and photon asymmetry is presented. Using a few reasonable assumptions we perform the first model-independent analysis of the E0+, E2- and M2- eta photoproduction multipoles. Making use of the well-known A3/2 helicity amplitude of the D13(1520) state we extract its branching ratio to the eta-N channel, Gamma(eta,N)/Gamma = (0.08 +- 0.01)%. At higher energies, we show that the photon asymmetry is extremely sensitive to small multipoles that are excited by photons in the helicity 3/2 state. The new GRAAL photon asymmetry data at higher energy show a clear signal of the F15(1680) excitation which permits extracting an F15(1680)->eta,N branching ratio of (0.15 +0.35 -0.10)%.Comment: 14 pages of LATEX including 7 postscript figure

Impact of Information Technology in Trade Facilitation on Small and Medium-Sized Enterprises in Bangladesh

F10, F13, F15

Multichannel parametrization of \pi N scattering amplitudes and extraction of resonance parameters

We present results of a new multichannel partial-wave analysis for \pi N scattering in the c.m. energy range 1080 to 2100 MeV. This work explicitly includes \eta N and K \Lambda channels and the single pion photoproduction channel. Resonance parameters were extracted by fitting partial-wave amplitudes from all considered channels using a multichannel parametrization that is consistent with S-matrix unitarity. The resonance parameters so obtained are compared to predictions of quark models

Strangeness production via electromagnetic probes: 40 years later

A brief review of the associated strangeness electromagnetic production is presented. Very recent K+ Lambda photoproduction data on the proton from threshold up to E=2.6 GeV are interpreted within a chiral constituent quark formalism, which embodies all known nucleonic and hyperonic resonances. The preliminary results of this work are reported here.Comment: 12 pages, 4 figures; Invited talk given at the International Symposium on Electrophoto-production of Strangeness on Nucleons and Nuclei, Sendai, Japan, June 16-18, 2003; World Scientific (to appear

Implementation of on-site velocity boundary conditions for D3Q19 lattice Boltzmann

On-site boundary conditions are often desired for lattice Boltzmann simulations of fluid flow in complex geometries such as porous media or microfluidic devices. The possibility to specify the exact position of the boundary, independent of other simulation parameters, simplifies the analysis of the system. For practical applications it should allow to freely specify the direction of the flux, and it should be straight forward to implement in three dimensions. Furthermore, especially for parallelized solvers it is of great advantage if the boundary condition can be applied locally, involving only information available on the current lattice site. We meet this need by describing in detail how to transfer the approach suggested by Zou and He to a D3Q19 lattice. The boundary condition acts locally, is independent of the details of the relaxation process during collision and contains no artificial slip. In particular, the case of an on-site no-slip boundary condition is naturally included. We test the boundary condition in several setups and confirm that it is capable to accurately model the velocity field up to second order and does not contain any numerical slip.Comment: 13 pages, 4 figures, revised versio

Probing the density dependence of the symmetry potential in intermediate energy heavy ion collisions

Based on the ultrarelativistic quantum molecular dynamics (UrQMD) model, the effects of the density-dependent symmetry potential for baryons and of the Coulomb potential for produced mesons are investigated for neutron-rich heavy ion collisions at intermediate energies. The calculated results of the Delta-/Delta++ and pi -/pi + production ratios show a clear beam-energy dependence on the density-dependent symmetry potential, which is stronger for the pi -/pi + ratio close to the pion production threshold. The Coulomb potential of the mesons changes the transverse momentum distribution of the pi -/pi + ratio significantly, though it alters only slightly the pi- and pi+ total yields. The pi- yields, especially at midrapidity or at low transverse momenta and the p-/pi+ ratios at low transverse momenta, are shown to be sensitive probes of the density-dependent symmetry potential in dense nuclear matter. The effect of the density-dependent symmetry potential on the production of both, K0 and K+ mesons, is also investigated

The [OIII]++Hβ\beta Equivalent Width Distribution at z≃\simeq7: Implications for the Contribution of Galaxies to Reionization

We quantify the distribution of [OIII]+H$\beta$ line strengths at z$\simeq$7 using a sample of 20 bright (M$_{\mathrm{UV}}$ $\lesssim$ $-$21) galaxies. We select these systems over wide-area fields (2.3 deg$^2$ total) using a new colour-selection which precisely selects galaxies at z$\simeq$6.63$-$6.83, a redshift range where blue Spitzer/IRAC [3.6]$-$[4.5] colours unambiguously indicate strong [OIII]$+$H$\beta$ emission. These 20 galaxies suggest a log-normal [OIII]$+$H$\beta$ EW distribution with median EW = 759$^{+112}_{-113}$ $\mathrm{\mathring{A}}$ and standard deviation = 0.26$^{+0.06}_{-0.05}$ dex. We find no evidence for strong variation in this EW distribution with UV luminosity. The typical [OIII]+H$\beta$ EW at z$\simeq$7 implied by our sample is considerably larger than that in massive star forming galaxies at z$\simeq$2, consistent with a shift toward larger average sSFR (4.4 Gyr$^{-1}$) and lower metallicities (0.16 Z$_\odot$). We also find evidence for the emergence of a population with yet more extreme nebular emission ([OIII]+H$\beta$ EW$>$1200 $\mathrm{\mathring{A}}$) that is rarely seen at lower redshifts. These objects have extremely large sSFR ($>$30 Gyr$^{-1}$), as would be expected for systems undergoing a burst or upturn in star formation. While this may be a short-lived phase, our results suggest that 20% of the z$\simeq$7 population has such extreme nebular emission, implying that galaxies likely undergo intense star formation episodes regularly at z$>$6. We argue that this population may be among the most effective ionizing agents in the reionization era, both in terms of photon production efficiency and escape fraction. We furthermore suggest that galaxies passing through this large sSFR phase are likely to be very efficient in forming bound star clusters.Comment: 20 pages, 11 figures. Accepted in MNRAS with minor revision