Off-diagonal helicity density matrix elements for vector mesons produced in polarized $e^+e^-$ processes

1999 ◽  
Vol 11 (3) ◽  
pp. 529-537 ◽  
Author(s):  
M. Anselmino ◽  
M. Bertini ◽  
F. Caruso ◽  
F. Murgia ◽  
P. Quintairos
Keyword(s):  
Density Matrix ◽  
Matrix Elements ◽  
Vector Mesons

Off-diagonal helicity density matrix elements for vector mesons produced in polarized

1999 ◽  
Vol 11 (3) ◽  
pp. 529 ◽  
Author(s):  
M. Anselmino ◽  
M. Bertini ◽  
F. Caruso ◽  
F. Murgia ◽  
P. Quintairos
Keyword(s):  
Density Matrix ◽  
Matrix Elements ◽  
Vector Mesons

scholarly journals Off-diagonal helicity density matrix elements for heavy vector mesons inclusively produced in NN,γN and ℓN interactions

1998 ◽  
Vol 438 (3-4) ◽  
pp. 347-352 ◽  
Author(s):  
M. Anselmino ◽  
M. Bertini ◽  
F. Murgia ◽  
B. Pire
Keyword(s):  
Density Matrix ◽  
Matrix Elements ◽  
Vector Mesons

Off-diagonal helicity density matrix elements for vector mesons produced at LEP

1998 ◽  
Vol 2 (3) ◽  
pp. 539-544 ◽  
Author(s):  
M. Anselmino ◽  
M. Bertini ◽  
F. Murgia ◽  
P. Quintairos
Keyword(s):  
Density Matrix ◽  
Matrix Elements ◽  
Vector Mesons

scholarly journals Off-diagonal helicity density matrix elements for vector mesons produced at LEP

1998 ◽  
Vol 2 (3) ◽  
pp. 539
Author(s):  
M. Anselmino ◽  
M. Bertini ◽  
F. Murgia ◽  
P. Quintairos
Keyword(s):  
Density Matrix ◽  
Matrix Elements ◽  
Vector Mesons

scholarly journals Spin Density Matrix Elements in Exclusive Production of Omega Mesons at HERMES

2016 ◽  
Vol 40 ◽  
pp. 1660063
Author(s):  
Hrachya Marukyan
Keyword(s):  
Density Matrix ◽  
Spin Density ◽  
Cross Section ◽  
Transverse Cross Section ◽  
Spin Density Matrix ◽  
Pion Pole ◽  
Matrix Elements ◽  
Unnatural Parity ◽  
Proton Data ◽  
Parity Exchange

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.

scholarly journals Exact density matrix elements for a driven dissipative system described by a quadratic Hamiltonian

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sh. Saedi ◽  
F. Kheirandish
Keyword(s):  
Density Matrix ◽  
Equations Of Motion ◽  
Dissipative System ◽  
Characteristic Functions ◽  
Matrix Elements ◽  
Exact Density ◽  
Quadratic Hamiltonian ◽  
Heisenberg Equations ◽  
Reduced Density ◽  
Heisenberg Equations Of Motion

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.

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