Search

Photoproduction of charged pions pairs off protons is studied within the invariant masses of the final state hadrons from 1.6 to 2.4 GeV at the Thomas Jefferson National Accelerator Facility with the CLAS detector. The data are included in the Bonn-Gatchina coupled-channel analysis and provide the information necessary to determine the branching fractions for most known nucleon and Delta resonances. Branching ratios are obtained here from an event based likelihood fit., Comment: 19 pages, 19 Figures

We analytically investigate the plasmons propagating in a homogeneous two-dimensional (2D) electron system, along the metal grating in the form of a periodic array of strip-shaped electrodes (gates) in the vicinity of the 2D system. We show that in the case of semi-infinite grating, the Tamm plasmon modes localized near and propagating along the grating edge can exist in the gaps of the plasmonic band structure provided that the last gate differs in width from the other gates. When the last gate is wider, the spectrum of the fundamental Tamm plasmon mode lies in the lowest frequency gap, below the first plasmonic band. Importantly, we find the mode to exist in this case only for finite values of the wave vector along the grating. Otherwise, if the width of the last gate is smaller, the Tamm plasmon modes occupy higher frequency gaps, and delocalized plasmons from the first frequency band become the lowest frequency excitations., Comment: 11 pages, 4 figures

We have developed the covariant approach for the partial wave analysis of the radiative decay of the vector meson into two pseudoscalar mesons based on the orbital momentum- intrinsic spin decomposition. This allowed us to include the data on the radiative J/{\Psi} decay into a large data base for analysis of the meson production reactions. The correspondence between partial wave amplitudes extracted in our approach and those extracted in the helicity basis is determined.

Branching ratios for the decay of hadrons with large width or near thresholds depend on their definition. We test different definitions and show that rather different branching ratios can be obtained. For wide resonances and for sequential decays with wide intermediate resonances, integration over the spectral functions is mandatory. The tests are performed exploiting the latest solution of the Bonn-Gatchina multi-channel analysis and published values for residues of light scalar mesons. For a resonance overlapping with a threshold, in case its pole lies in a non-adjacent sheet, we show how the total width, needed for the branching ratios, does not correspond to the imaginary part of the pole position. We use the Madrid-Krakow dispersive parameterizations to illustrate this situation with the $f_0(980)$., Comment: Report, 9 pages (extended to light scalar mesons)

The tensor glueball is searched for in BESIII data on radiative $J/\psi$ decays into $\pi^0\pi^0$ and $K_sK_s$. The $\pi\pi$ invariant mass distribution exhibits an enhancement that can be described by a pole at $(2210\pm 60) -i(180\pm 60)$\,MeV. We speculate if the tensor glueball could be distributed among high-mass tensor mesons., Comment: 8 pages, 3 figures, 2 Tables

The LHC energies are those at which the asymptotic regime in hadron-hadron diffractive collisions ($pp,\pi p,\pi\pi$) might be switched on. Based on results of the Dakhno-Nikonov eikonal model which is a generalization of the Good-Walker eikonal approach for a continuous set of channels, we present a picture for transformation of the constituent quark mode to the black disk one. In the black disk mode ($\sqrt s \geq 10$ TeV) we have a growth of the logarithm squared type for total and elastic cross sections, $\sigma_{tot}\sim\ln^2s$ and $\sigma_{el}\sim\ln^2s$, and $(\tau={\bf q}_\perp^2\sigma_{tot})$-scaling for diffractive scattering and diffractive dissociation of hadrons. The diffractive dissociation cross section grows as $\sigma_{D}\sim\ln{s}$, $\sigma_{DD}\sim\ln{s}$, and their relative contribution tends to zero: $\sigma_{D}/\sigma_{tot}\to 0$, $\sigma_{DD}/\sigma_{tot}\to 0$. Asymptotic characteristics of diffractive and total cross sections are universal, and this results in the asymptotical equality of cross sections for all types of hadrons (the Gribov's universality). The energy scale for switching on the asymptotic mode is estimated for different processes., Comment: 14 pages. arXiv admin note: text overlap with arXiv:1310.2839

Proton-proton total and elastic cross sections are considered in the Dakhno-Nikonov eikonal model [L.G. Dakhno, V.A. Nikonov, Eur. Phys. J. A8, 209 (1999)] at ultra-high energies. The model takes into account the quark structure of hadrons and the gluon structure of the supercritical pomeron that results in colour screening. The pomeron is considered as an input interaction term. The model gives a reasonably good description of the preLHC and LHC data for $pp$ collisions with a growth of the type $\ln^2s$ for total and elastic cross sections and $(\tau={\bf q}_\perp^2\ln^2s)$-scaling for diffractive scattering. We present parameters of the supercritical pomeron and provide predictions for the energy region $\sqrt{s}\sim 10^2-10^4$ TeV., Comment: 5 pages. Typos and PACS corrected

We describe the meson-meson data for the ($IJ^{PC}=00^{++}$) wave at $280\leq\sqrt s\leq 1900$ MeV in two approaches: (i) the K-matrix approach and (ii) the dispersion relation D-matrix method. With a good description of low energy data (at $280\leq\sqrt s\leq 900$ MeV) as well as the data of two-meson transition amplitudes and antiproton-proton annihilation into three pseudoscalar meson states (at $450\leq\sqrt s\leq 1950$ MeV) we have found the positions of the resonance poles: (i) for the $\sigma$ meson pole: $M_\sigma = (390\pm 35)-i(235\pm 50)$ MeV; (ii) two poles for the $f_0(980)$, on the second sheet (under the $\pi\pi$ cut): $M_{I} = (1011\pm 5)-i(35\pm 5)$ MeV, and on the third sheet (under the $\pi\pi$ and $K\bar K$ cuts), $M_{II} = (1035\pm 50)-i(460\pm 50)$ MeV; for the $f_0(1370)$ meson, $M= (1285\pm 30)-i(160\pm 20)$ MeV; for the $f_0(1500)$ meson, $M = (1488\pm 4)-i(53\pm 5)$ MeV; for the $f_0(1790)$ meson, $M = (1775\pm 25)-i(140\pm 15)$ MeV and for the broad state $f_0(1200-1600)$ $M=(1540\pm 120)-i(550\pm 70)$ MeV. Our estimation of the scalar-isoscalar scattering length obtained under different parameterizations and assumptions about the quality of low energy $\pi\pi$ scattering data is $a^0_0=(0.215\pm 0.040)\mu^{-1}_\pi$. We also discuss the idea according to which the $\sigma$-meson could be a remnant of the confinement singularity, $1/s^2$, in a white channel., Comment: 23 pages