Spin-Exchange Effects on Density-Matrix Elements

1971 ◽  
Vol 3 (1) ◽  
pp. 505-508 ◽  
Author(s):  
Peter A. Valberg
1956 ◽  
Vol 103 (2) ◽  
pp. 280-286 ◽  
Author(s):  
James Ross Macdonald

2010 ◽  
Vol 21 (2) ◽  
pp. 226-233
Author(s):  
M. M. Fujimoto ◽  
S. E. Michelin ◽  
F. Arretche ◽  
K.T. Mazon ◽  
M.-T. Lee ◽  
...  

1984 ◽  
Vol 110 (3) ◽  
pp. 280-284 ◽  
Author(s):  
A.I. Grant ◽  
N.J.B. Green ◽  
P.J. Hore ◽  
K.A. McLauchlan

2016 ◽  
Vol 40 ◽  
pp. 1660063
Author(s):  
Hrachya Marukyan

Exclusive electroproduction of [Formula: see text] mesons on unpolarized hydrogen and deuterium targets is studied at HERMES in the kinematic region of [Formula: see text], [Formula: see text], and [Formula: see text]. The data were accumulated during the 1996-2007 running period using the [Formula: see text] longitudinally polarized electron or positron beams at HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio shows that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are derived and presented in projections of [Formula: see text] or [Formula: see text]. Violation of s-channel helicity conservation is observed for some of these elements. A sizable contribution from unnatural-parity-exchange amplitudes is found and the phase shift between those amplitudes that describe transverse [Formula: see text] production by longitudinal and transverse virtual photons is determined for the first time. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sh. Saedi ◽  
F. Kheirandish

AbstractFor a prototype quadratic Hamiltonian describing a driven, dissipative system, exact matrix elements of the reduced density matrix are obtained from a generating function in terms of the normal characteristic functions. The approach is based on the Heisenberg equations of motion and operator calculus. The special and limiting cases are discussed.


2006 ◽  
Vol 2006 (12) ◽  
pp. P12017-P12017 ◽  
Author(s):  
Jun Sato ◽  
Masahiro Shiroishi ◽  
Minoru Takahashi

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