arXiv subjects

S. S. Kamalov

Publications and source records attributed to S. S. Kamalov.

42 records · Page 3Linked to original sources

arXiv1997

Meson Exchange Currents in Kaon Scattering on the Lightest Nuclei

The K^+ scattering on the lightest nuclei, d, 3He and 4He is studied in the framework of multiple scattering theory. Effects from MEC tied to the K^+N-->KNpi reaction are evaluated. We found that at momentum transfers Q^2<0.5 (GeV/c)^2 contributions from MEC are much smaller than kaon rescattering corrections. This makes the conventional multiple scattering picture a reliable tool to study these reactions in this kinematical domain and to extract the K^+n scattering amplitude from the K^+d data. At larger transferred momentum MEC can become more relevant.

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arXiv1996

Elastic Pion Scattering on the Deuteron in a Multiple Scattering Model

Pion elastic scattering on deuterium is studied in the KMT multiple scattering approach developed in momentum space. Using a Paris wave function and the same methods and approximations as commonly used in pion scattering on heavier nuclei excellent agreement with differential cross section data is obtained for a wide range of pion energies. Only for $T_π>250$ MeV and very backward angles, discrepancies appear that are reminiscent of disagreements in pion scattering on $^3$He, $^3$H, and $^4$He. At low energies the second order corrections have been included. Polarization observables are studied in detail. While tensor analyzing powers are well reproduced, vector analyzing powers exhibit dramatic discrepancies.

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arXiv1996

Coherent $π^0$ and $η$ Photoproduction on the Deuteron

Coherent pion photoproduction, $d(γ,π^0)d$, is calculated in a coupled channels approach in momentum space using an elementary production operator that includes Born terms, vector meson exchange and $M1/E2$ $Δ$-resonance excitation. The final state interaction is treated in the KMT multiple scattering approach that describes $πd$ elastic scattering well. Differential cross sections are found to agree well with existing ($γ, π^0$) data. The polarization observables $Σ, iT_{11}$ and the tensor analyzing powers are predicted for forthcoming experiments. A number of transparent relationships between polarization observables and the elementary production operator is derived. Finally, calculations are performed for coherent eta photoproduction, $d (γ, η)d$, in the threshold region which agree well with a very recent Mainz experiment.

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arXiv1994

Two-body Mechanisms in Pion Photoproduction on the Trinucleon

A breakdown of the Impulse Approximation is studied in pion photoproduction on $^3$He at high momentum transfers. The usual DWIA formalism with Faddeev wave functions which works well for small momentum transfers deviates from experimental measurements by up to two orders of magnitude for $Q^2>6 fm^{-2}$. It is found that the explicit inclusion of two-body mechanisms, where the photon is absorbed on one nucleon and the pion is emitted from another nucleon can restore agreement with the data.

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arXiv1994

The $η$NN Coupling in Eta Photoproduction

Low-energy eta photoproduction on the nucleon is studied in an effective Lagrangian approach that contains Born terms, vector meson and nucleon resonance contributions. The resonance sector includes the $S_{11}(1535)$, $P_{11}(1440)$ and $D_{13}(1520)$ states whose couplings are fixed by independent electromagnetic and hadronic data. The available $(γ,η)$ data are employed to discuss the difference between pseudoscalar and pseudovector Born terms and to determine the magnitude of the $ηNN$ coupling constant. We present multipoles that are most sensitive to the various model ingredients and demonstrate how these multipoles may be accessed in polarization observables. Cross section calculations are presented for eta photoproduction on light nuclei.

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arXiv1993

Pion interaction with the trinucleon up to the eta production threshold

Pion elastic, charge exchange scattering and induced eta production on the trinucleon systems are investigated in a coupled-channels approach in momentum space with Fadeev wave functions. The channel $πN \rightarrow ηN$ is included using an isobar model with S-, P-, and D-wave resonances. While the coherent reactions like $^3$He($π,π)^3$He can be reasonably well reproduced up to $T_π$=500 MeV, large discrepancies appear for the incoherent processes, $^3$He($π^-,π^0)^3$H and $^3$He($π^-,η)^3$H at backward angles and energies above $Δ$-resonance. In the forward direction the $(π,η)$ calculations underestimate the experimental measurements very close to threshold but agreement with the data improves with increasing pion energy. Predictions are made for the asymmetries of the various reactions on polarized $^3$He.

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