Akopov, N.Z.
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Asymmetry of the cross section of the reaction $\gamma$P $\rightarrow$ P$\pi^{0}$ in the energy interval 0.9-1.65 GeV at $\theta _{\pi}^{0 cms}$ = 110°

Abramyan, L.O. ; Avakyan, R.O. ; Akopov, N.Z. ; et al.
JETP Lett. 23 (1976) 375-378, 1976.
Inspire Record 1393126 DOI 10.17182/hepdata.39803

None

2 data tables
Table 1

THE ERRORS INCLUDE THE 10 PCT ERROR IN THE EFFECTIVE PHOTON POLARIZATION.

Table 2

No description provided.


Spin density matrix elements in exclusive $\omega$ electroproduction on $^1$H and $^2$H targets at 27.5 GeV beam energy

The HERMES collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Eur.Phys.J.C 74 (2014) 3110, 2014.
Inspire Record 1305286 DOI 10.17182/hepdata.70751

Exclusive electroproduction of $\omega$ mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of Q$^2$>1.0 GeV$^2$, 3.0 GeV < W < 6.3 GeV, and -t'< 0.2 GeV$^2$. Results on the angular distribution of the $\omega$ meson, including its decay products, are presented. The data were accumulated with the HERMES forward spectrometer during the 1996-2007 running period using the 27.6 GeV longitudinally polarized electron or positron beam of HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio reveals that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are presented in projections of Q$^2$ or -t'. 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 $\omega$ production by longitudinal and transverse virtual photons, $\gamma^{*}_{L} \to \omega_{T}$ and $\gamma^{*}_{T} \to \omega_{T}$, is determined for the first time. A hierarchy of helicity amplitudes is established, which mainly means that the unnatural-parity-exchange amplitude describing the $\gamma^*_T \to \omega_T$ transition dominates over the two natural-parity-exchange amplitudes describing the $\gamma^*_L \to \omega_L$ and $\gamma^*_T \to \omega_T$ transitions, with the latter two being of similar magnitude. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions, which are of unnatural parity.

9 data tables
Table 1

The 23 unpolarized and polarized $\omega$ SDMEs from the proton and deuteron data.

Table 2

The 23 unpolarized and polarized $\omega$ SDMEs for the proton data in $Q^2$ intervals: $1.00 - 1.57 - 2.55 - 10.00$ GeV$^2$.

Table 3

The 23 unpolarized and polarized $\omega$ SDMEs for the proton data in $-t'$ intervals: $0.000 - 0.044 - 0.105 - 0.200$ GeV$^2$.

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MEASUREMENT OF POLARIZATION OF RECOIL PROTONS IN PI0 PHOTOPRODUCTION FOR THETA* (PI0) = 60-degrees IN RESONANCE REGION. (IN RUSSIAN)

Avakian, R.O. ; Avakian, E.O. ; Avetisian, A.E. ; et al.
Sov.J.Nucl.Phys. 37 (1983) 199-201, 1983.
Inspire Record 183972 DOI 10.17182/hepdata.17739

None

1 data table
Table 1

Axis error includes +- 0.0/0.0 contribution (?////NO DISCUSSION OF ERRORS AT ALL).


Measurement of Asymmetry in Photoproduction of pi0 Meson in the Resonance Region

Avakian, R.O. ; Avakian, E.O. ; Avetisian, A.E. ; et al.
Yad.Fiz. 26 (1977) 1014-1017, 1977.
Inspire Record 126317 DOI 10.17182/hepdata.19036

None

1 data table
Table 1

Axis error includes +- 10/10 contribution.