Influence of final-state interaction on double spin asymmetries in incoherent π+-photoproduction on the deuteron near threshold

2020 ◽  
Vol 29 (08) ◽  
pp. 2050056
Author(s):  
E. M. Darwish ◽  
H. M. Al-Ghamdi

Incoherent [Formula: see text]-photoproduction on the deuteron is investigated for photon energies near threshold with particular focus on beam-target double spin asymmetries. The analysis is based on a [Formula: see text] reaction model in which realistic elementary amplitudes for [Formula: see text], [Formula: see text] and [Formula: see text] are incorporated. Numerical results on all possible beam-target double spin asymmetries of the differential and total cross-sections in the photon energy region near threshold are presented. Effects of [Formula: see text] and [Formula: see text] final-state interactions are investigated and their roles are found to be important.

2009 ◽  
Vol 18 (05n06) ◽  
pp. 1271-1281 ◽  
Author(s):  
B. K. JAIN ◽  
N. J. UPADHYAY ◽  
K. P. KHEMCHANDANI ◽  
N. G. KELKAR

We present a study of the η production at low energies in pd collision with 3He and pd nuclear systems in the final state. The η production mechanism is described by a two-step model and the final state interactions are included fully. The η - d and η - 3He final state interactions are incorporated through the solution of the Lippmann Schwinger equation for a half off-shell η - AT-matrix. For η - d this t -matrix is written in a factorized form, with an off-shell form factor multiplying an on-shell part having the scattering length representation. The p - d final state interaction is included by multiplying the production matrix element by the inverse of the Jost function which includes the strong as well as the Coulomb interaction. The total cross sections are found to be strongly affected by both the η - d and the p - d final state interactions. The η - 3HeT-matrix is obtained in the Finite Rank Approximation (FRA) by solving few-body equations. The calculated total cross sections are in good accord with the available experimental data. Through the time delay method of Wigner, we also explore the possibility of the existence of quasi-bound η-3 He mesic states in this η - 3He T -matrix. We find that the T -matrix which reproduces the low energy pd → 3He η data implies a quasi-bound eta state near threshold. This is in accord with experimental indications.


2005 ◽  
Vol 20 (02n03) ◽  
pp. 643-645 ◽  
Author(s):  
H.-H. ADAM ◽  
A. KHOUKAZ ◽  
N. LANG ◽  
T. LISTER ◽  
R. SANTO ◽  
...  

Measurements on the η meson production in proton-deuteron collisions have been performed using the COSY-11 facility at COSY (Jülich). Here we present preliminary results on total and differential cross sections for the pd→3 He η reaction at five excess energies between Q=5.1 and Q=40.6 MeV. The obtained angular distributions for the emitted η mesons in the center of mass system expose a transition from an almost isotropic emission to a highly anisotropic distribution. The extracted total cross sections support a strong η-3 He final state interaction and will be compared with model predictions.


2011 ◽  
Vol 26 (03n04) ◽  
pp. 539-541 ◽  
Author(s):  
MICHAŁ SILARSKI

In this article we present studies of the near threshold pp → ppK+K- reaction in view of the K+K- final state interaction. The investigations include analysis of both the low-energy K+K- invariant mass distributions measured by COSY-11 collaboration at excess energies of Q = 10 MeV and Q = 28 MeV and the near threshold excitation function for the pp → ppK+K- reaction. As a result of these studies we have estimated the K+K- scattering length more precise compared to the previous analysis based only on the analysis of the differential cross sections.


2014 ◽  
Vol 26 ◽  
pp. 1460082 ◽  
Author(s):  
IGOR I. STRAKOVSKY ◽  
WILLIAM J. BRISCOE ◽  
ALEXANDER E. KUDRYAVTSEV ◽  
VLADIMIR E. TARASOV

We present an overview of the SAID group effort to analyze new γn → π-p cross sections vs. the world database to get new multipoles and determine neutron electromagnetic couplings. The differential cross section for the processes γn → π-p was extracted from new measurements at CLAS and MAMI-B accounting for Fermi motion effects in the impulse approximation (IA) as well as NN- and πN-FSI effects beyond the IA. We evaluated results of several pion photoproduction analyses and compared πN PWA results as a constraint for analyses of pion photoproduction data (Watson's theorem).


2009 ◽  
Vol 18 (05n06) ◽  
pp. 1383-1388
Author(s):  
N. J. UPADHYAY ◽  
N. G. KELKAR ◽  
K. P. KHEMCHANDANI ◽  
B. K. JAIN

We present a calculation for η production in the p-6Li fusion near threshold including the η-7Be final state interaction (FSI). We consider the 6Li and 7Be nuclei as α-d and α-3He clusters respectively. The calculations are done for the lowest states of 7 Be with [Formula: see text] resulting from the L = 1 radial wave function. The η-7Be interaction is incorporated through the η-7BeT–matrix, constructed from the medium modified matrices for the η-3He and η-α systems. These medium modified matrices are obtained by solving few body equations, where the scattering in nuclear medium is taken into account.


2009 ◽  
Author(s):  
S. Dytman ◽  
Federico Sanchez ◽  
M. Sorel ◽  
Luis Alvarez-Ruso

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