Search results for " Resonances"
showing 10 items of 51 documents
Charm and Hidden Charm Scalar Resonances in Nuclear Matter
2009
18th Particles and Nuclei International Conference (PANIC08). Eilat, ISRAEL, NOV 09-14, 2008
Strangeness and charm in nuclear matter
2012
The properties of strange (K, (K) over bar and (K) over bar*) and open-charm (D, (D) over bar and D*) mesons in dense matter are studied using a unitary approach in coupled channels for meson-baryon scattering. In the strangeness sector, the interaction with nucleons always comes through vector-meson exchange, which is evaluated by chiral and hidden gauge Lagrangians. For the interaction of charmed mesons with nucleons we extend the SU(3) Weinberg-Tomozawa Lagrangian to incorporate spin-flavor symmetry and implement a suitable flavor symmetry breaking. The in-medium solution for the scattering amplitude accounts for Pauli blocking effects and meson self-energies. On one hand, we obtain the …
Meson and baryon resonances
2009
6 pages, 1 table.-- PACS nrs.: 13.75.Lb, 14.40.Cs, 12.40.Vv, 12.40.Yx.-- Talk at the 2008 International Conference on Particles And Nuclei (PANIC08, Nov 9-14, 2008, Eilat, Israel).
First measurement of the polarization observable E and helicity-dependent cross sections in single π 0 photoproduction from quasi-free nucleons
2017
The double-polarization observable $E$ and the helicity-dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$ have been measured for the first time for single $\pi^{0}$ photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the $\pi^0$ meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Effects from nuclear Fermi motion were removed by a kinematic reconstruction of the $\pi^{0}N$ final state. A comparison to data mea…
Structure of pion photoproduction amplitudes
2018
We derive and apply the finite energy sum rules to pion photoproduction. We evaluate the low energy part of the sum rules using several state-of-the-art models. We show how the differences in the low energy side of the sum rules might originate from different quantum number assignments of baryon resonances. We interpret the observed features in the low energy side of the sum rules with the expectation from Regge theory. Finally, we present a model, in terms of a Regge-pole expansion, that matches the sum rules and the high-energy observables.
A finite difference time domain model for the Titan ionosphere Schumann resonances
2007
[1] This paper presents a numerical approach to model the electrical properties of Titan's atmosphere. The finite difference time domain technique is applied to model the atmosphere of Saturn's satellite in order to determine Schumann resonant frequencies and electromagnetic field distributions at the extremely low frequency range. Spherical coordinates are employed, and periodic boundary conditions are implemented in order to exploit the symmetry in rotation of the celestial body. Results are compared with a previous model using the transmission line matrix method up to 180 km altitude. For the first time a numerical FDTD model up to 800 km altitude is carried out, and we report lower freq…
Nuclear symmetry energy and neutron skins derived from pygmy dipole resonances
2007
By exploiting Coulomb dissociation of high-energy radioactive beams of the neutron-rich nuclei $^{129\ensuremath{-}132}\mathrm{Sn}$ and $^{133,134}\mathrm{Sb}$, their dipole-strength distributions have been measured. A sizable fraction of ``pygmy'' dipole strength, energetically located below the giant dipole resonance, is observed in all of these nuclei. A comparison with available pygmy resonance data in stable nuclei ($^{208}\mathrm{Pb}$ and $N=82$ isotones) indicates a trend of strength increasing with the proton-to-neutron asymmetry. On theoretical grounds, employing the RQRPA approach, a one-to-one correlation is found between the pygmy strength and parameters describing the density d…
Predictions for η→ηπ+π− producing f0(500), f0(980) and a0(980)
2017
Abstract We perform calculations for the η c → η π + π − decay using elements of SU(3) symmetry to see the weight of different trios of pseudoscalars produced in this decay, prior to the final state interaction of the mesons. After that, the interaction of pairs of mesons, leading finally to η π + π − , is done using the chiral unitary approach. We evaluate the π + π − and πη mass distributions and find large and clear signals for f 0 ( 500 ) , f 0 ( 980 ) and a 0 ( 980 ) excitation. The reaction is similar to the χ c 1 → η π + π − , which has been recently measured at BESIII and its implementation and comparison with these predictions will be very valuable to shed light on the nature of th…
Pole positions and residues from pion photoproduction using the Laurent-Pietarinen expansion method
2014
We have applied a new approach to determine the pole positions and residues from pion photoproduction multipoles. The method is based on a Laurent expansion of the partial wave T-matrices, with a Pietarinen series representing the regular part of energy-dependent and single-energy photoproduction solutions. The method has been applied to multipole fits generated by the MAID and GWU/SAID groups. We show that the number and properties of poles extracted from photoproduction data correspond very well to results from $\pi$N elastic data and values cited by Particle Data Group (PDG). The photoproduction residues provide new information for the electromagnetic current at the pole position, which …
V P gamma radiative decay of resonances dynamically generated from the vector meson-vector meson interaction
2010
We evaluate the radiative decay into a vector, a pseudoscalar and a photon of several resonances dynamically generated from the vector-vector interaction. The process proceeds via the decay of one of the vector components into a pseudoscalar and a photon, which have an invariant mass distribution very different from phase space as a consequence of the two vector structure of the resonances. Experimental work along these lines should provide useful information on the nature of these resonances.