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Study on the cross section asymmetry of deuteron photodisintegration induced by low energy polarized γ quanta

Barannik, V.P. ; Gorbenko, V.G. ; Gushchin, V.A. ; et al.

Yad.Fiz. 38 (1983) 1108-1100, 1983.

Inspire Record 1408810 DOI 10.17182/hepdata.17732

Results are presented on measured asymmetry parameter in the cross sections of the deuteron photodesintegration by linearly polarized photon beam in the energy range 40-70 MeV for the proton emission angles of 75 and 90 deg in the c. m. s. The experimental data are compared with the theoretical calculations by Partovi, Arenhovel, as well as with calculations performed within an invariant approach with gauge-invariant amplitudes in the pole approximation. The results of the calculation by Arenhovel and the present calculations satisfactorily agree with the experimental data, while the Partovi theory does not describe the asymmetry parameter measurements for photon energies above 40 MeV

1 data table

Table 1

No description provided.

Measurement of the polarization parameter P in elastic π+p scattering at 335, 370, and 410 MeV

Bekrenev, V.S. ; Beloglazov, Yu.A. ; Gaditskii, V.G. ; et al.

JETP Lett. 35 (1982) 148, 1982.

Inspire Record 1408359 DOI 10.17182/hepdata.70446

None

7 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Cross-section asymmetry in two-particle photodisintegration of helium-3 by linearly polarized protons

Belyaev, A.A. ; Ganenko, V.B. ; Get'man, V.A. ; et al.

Sov.J.Nucl.Phys. 44 (1986) 181-183, 1986.

Inspire Record 1392511 DOI 10.17182/hepdata.17441

None

2 data tables

Table 1

No description provided.

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$^2$.