scholarly journals DEEPLY VIRTUAL AND EXCLUSIVE PRODUCTION OF THE OMEGA MESON

2005 ◽  
Vol 20 (08n09) ◽  
pp. 1943-1946
Author(s):  
◽  
M. GARÇON ◽  
L. MORAND ◽  
D. DORÉ ◽  
J.-M. LAGET ◽  
...  
Keyword(s):  
Density Matrix ◽  
Momentum Transfer ◽  
Cross Sections ◽  
Spin Density Matrix ◽  
Matrix Elements ◽  
Photon Virtuality ◽  
Parton Distributions ◽  
Exclusive Production ◽  
Generalized Parton Distributions ◽  
Omega Meson

Exclusive ω electroproduction off the proton was measured at the highest possible four-momentum transfer with the (close to) 6 GeV beam now available at CEBAF. Cross sections are presented, together with an analysis of the ω spin density matrix elements. Indications are that π0 exchange in the t-channel (or rather the exchange of the corresponding saturating Regge trajectory) seems to dominate the process γ*p→ωp, even for photon virtuality Q2 as large as 5 GeV2. Contributions of the handbag type, related to Generalized Parton Distributions in the nucleon, are therefore difficult to extract from this particular process.

Study of cross sections and spin-density matrix elements in 5 GeV/c π+p four-pronged interactions

1971 ◽  
Vol 25 (1) ◽  
pp. 109-140 ◽  
Author(s):  
C.L. Pols ◽  
D.J. Schotanus ◽  
D.Z. Toet ◽  
R.T. Van de Walle ◽  
K. Böckmann ◽  
...  
Keyword(s):  
Density Matrix ◽  
Spin Density ◽  
Cross Sections ◽  
Spin Density Matrix ◽  
Matrix Elements

scholarly journals Differential cross sections and spin density matrix elements for the reactionγp→pω

2009 ◽  
Vol 80 (6) ◽  
Author(s):  
M. Williams ◽  
D. Applegate ◽  
M. Bellis ◽  
C. A. Meyer ◽  
K. P. Adhikari ◽  
...  
Keyword(s):  
Density Matrix ◽  
Spin Density ◽  
Cross Sections ◽  
Differential Cross ◽  
Spin Density Matrix ◽  
Differential Cross Sections ◽  
Matrix Elements

scholarly journals Differential cross sections and spin density matrix elements for γp → ϕp from CLAS

2011 ◽  
Author(s):  
Biplab Dey ◽  
Curtis A. Meyer ◽  
Atsushi Hosaka ◽  
Kanchan Khemchandani ◽  
Hideko Nagahiro ◽  
...  
Keyword(s):  
Density Matrix ◽  
Spin Density ◽  
Cross Sections ◽  
Differential Cross ◽  
Spin Density Matrix ◽  
Differential Cross Sections ◽  
Matrix Elements

scholarly journals Recent results from COMPASS on the GPD program

2018 ◽  
Vol 192 ◽  
pp. 00012
Author(s):  
Andrzej Sandacz
Keyword(s):  
Density Matrix ◽  
Cross Section ◽  
Cross Sections ◽  
Azimuthal Angle ◽  
Meson Production ◽  
Spin Density Matrix ◽  
Transverse Size ◽  
Matrix Elements ◽  
Absolute Value ◽  
First Results

The dedicated COMPASS GPD program started in 2012 with a short pilot ’DVCS run’ and the first results from this run on DVCS, exclusive π0 and exclusive ω channels have been obtained. From the sum of cross sections measured with positive and negative beam polarities the DVCS cross-section and its dependence on the squared four-momentum transfer t have been extracted. It allowed a first estimate of the transverse size of the partonic distribution of the nucleon √〈r2⊥〉 i in a range of intermediate xBj with a mean xBj value of 0.056. We report also on the absolute value of the cross section for exclusive π0 production and its dependence on t and azimuthal angle ϕ between the scattering plane and π0 production plane. These measurements are aiming to constrain the GPDs, in particular chiral-odd (transversity) GPDs. Further, we present results on the spin density matrix elements for exclusive ω meson production and discuss the contributions from unnaturaly parity exchanges and from transitions that do not conserve helicity.

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