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On photoexcitation of baryon antidecuplet  [PDF]
M. V. Polyakov,A. Rathke
Physics , 2003, DOI: 10.1140/epja/i2003-10029-y
Abstract: We show that the photoexcitation of the baryon antidecuplet, suggested by the soliton classification of low-lying baryons, is strongly suppressed on the proton target. The process occurs mostly on the neutron target. This qualitative prediction can be useful in identifying the non-exotic members of the antidecuplet in the known baryon spectrum. We also analyze the interrelation between photocouplings of various baryon multiplets in the soliton picture and in the nonrelativistic quark model.
In-medium properties of the D13(1520) nucleon resonance  [PDF]
B. Krusche,J. Ahrens,R. Beck,I. J. D. MacGregor,J. C. McGeorge,V. Metag,H. Stroeher
Physics , 2003, DOI: 10.1103/PhysRevLett.86.4764
Abstract: The in-medium properties of the D13(1520) nucleon resonance were studied via photoproduction of pi0-mesons from nuclei (C, Ca, Nb, Pb) with the TAPS-detector at the Mainz MAMI accelerator. The inclusive (single and multiple pion production) data disagree with model predictions which explain the disappearance of the second resonance bump in total photoabsorption via a medium modification of the D13 --> N rho decay. The exclusive single pi0 production data show no broadening of the resonance structure beyond Fermi smearing. Although due to final state interaction effects pion production tests the nucleus at densities less than the average nuclear density, both results together cast doubt on attempts to explain the vanishing of the second resonance bump for heavy nuclei by a broadening of the D13-resonance in nuclear matter.
Extraction of the D13(1520) photon-decay couplings from pion- and eta-photoproduction data  [PDF]
R. L. Workman,R. A. Arndt,I. I. Strakovsky
Physics , 1999, DOI: 10.1103/PhysRevC.62.048201
Abstract: We compare results for the D13(1520) photon-decay amplitudes determined in analyses of eta- and pion-photoproduction data. The ratio of helicity amplitudes (A_3/2 / A_1/2), determined from eta-photoproduction data, is quite different from that determined in previous analyses of pion-photoproduction data. We consider how strongly the existing pion-photoproduction data constrain both this ratio and the individual photon-decay amplitudes.
The Role of the D13 (1520) Resonance in eta Electroproduction  [PDF]
R. M. Davidson,N. Mathur,N. C. Mukhopadhyay
Physics , 1999, DOI: 10.1103/PhysRevC.62.058201
Abstract: We investigate the electroproduction of eta mesons below a center of momentum energy of 1.6 GeV, with particular emphasis on the roles of the N*(1535) and N*(1520) resonances. Using the effective Lagrangian approach, we show that the transverse helicity amplitude of the N*(1535) can be extracted with good accuracy from the new eta electroproduction data, under reasonable assumptions for the strength of the longitudinal helicity amplitude. In addition, although the differential cross section is found to to have a small sensitivity to the N*(1520) resonance, it is shown that a recently completed double polarization experiment is very sensitive to this resonance.
Electroexcitation of the P33(1232), P11(1440), D13(1520), S11(1535) at Q^2=0.4 and 0.65(GeV/c)^2  [PDF]
I. G. Aznauryan,V. D. Burkert,H. Egiyan,K. Joo,R. Minehart,L. C. Smith
Physics , 2004, DOI: 10.1103/PhysRevC.71.015201
Abstract: Using two approaches: dispersion relations and isobar model, we have analyzed recent high precision CLAS data on cross sections of \pi^0, \pi^+, and \eta electroproduction on protons, and the longitudinally polarized electron beam asymmetry for p(\vec{e},e'p)\pi^0 and p(\vec{e},e'n)\pi^+. The contributions of the resonances P33(1232), P11(1440), D13(1520), S11(1535) to \pi electroproduction and S11(1535) to \eta electroproduction are found. The results obtained in the two approaches are in good agreement with each other. There is also good agreement between amplitudes of the \gamma^* N \to S11(1535) transition found in \pi and \eta electroproduction. For the first time accurate results are obtained for the longitudinal amplitudes of the P11(1440), D13(1520) and S11(1535) electroexcitation on protons.
Exchange Currents in Photoproduction of Baryon Resonances  [PDF]
U. Meyer,A. J. Buchmann,Amand Faessler
Physics , 1998, DOI: 10.1016/S0370-2693(97)00840-X
Abstract: We calculate photoexcitation amplitudes for several nucleon and delta resonances. We use a chiral quark model including two-body exchange currents. The two-body currents give important contributions. For the delta (1232) and the D13 (1520) we observe that the individual exchange current contributions considerably cancel each other while in the case of the Roper resonance and the S11 (1535) we get a reinforcement of the two-body amplitudes. In comparison with present experimental data, we obtain both for the S11 (1535) and for the Roper resonance an improvement with respect to the impulse approximation.
Radiative decay of the Lambda(1520)  [PDF]
M. Doring,E. Oset,Sourav Sarkar
Physics , 2006, DOI: 10.1103/PhysRevC.74.065204
Abstract: A recently developed non-perturbative chiral approach to dynamically generate the (3/2^-) baryon resonances has been extended to investigate the radiative decays Lambda^*(1520) --> gamma Lambda(1116) and Lambda^*(1520) --> gamma Sigma^0(1193). We show that the Lambda^*(1520) decay into gamma Lambda is an ideal test for the need of extra components of the resonance beyond those provided by the chiral approach since the largest meson-baryon components give no contribution to this decay. The case is different for gamma Sigma decay where the theory agrees with experiment, though the large uncertainties of these data call for more precise measurements.
The composite nature of the $Λ(1520)$ resonance  [PDF]
F. Aceti,E. Oset,L. Roca
Physics , 2014, DOI: 10.1103/PhysRevC.90.025208
Abstract: Recently, the Weinberg compositeness condition of a bound state was generalized to account for resonant states and higher partial waves. We apply this extension to the case of the $\Lambda(1520)$ resonance and quantify the weight of the meson-baryon components in contrast to other possible genuine building blocks. This resonance was theoretically obtained from a coupled channels analysis using the s-waves $\pi\Sigma^*$, $K\Xi^*$ and the d-waves $\bar{K}N$ and $\pi\Sigma$ channels applying the techniques of the chiral unitary approach. We obtain that this resonance is essentially dynamically generated from these meson-baryon channels, leaving room for only $15 \%$ weight of other kind of components into its wave function.
$Λ(1520)$ at finite density  [PDF]
M. M. Kaskulov,E. Oset
Physics , 2005, DOI: 10.1063/1.2220307
Abstract: We study the decay channels of the $\Lambda(1520)$ in a nuclear medium and find a sizable change - of the order of factor five - of the width of this hyperon at normal nuclear matter density. The mass shift of the $\Lambda(1520)$ is moderate.
NEWS AND EVENTS
Editor Journal
Journal of Global Pharma Technology , 2010, DOI: 10.1234/jgpt.v2i2.130
Abstract: News and Events
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