HEPData Search

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Diffractive Phi-meson photoproduction on proton near threshold.

The LEPS collaboration Mibe, T. ; Chang, W.C. ; Nakano, T. ; et al.

Phys.Rev.Lett. 95 (2005) 182001, 2005.

Inspire Record 684863 DOI 10.17182/hepdata.31587

Photoproduction of $\phi$-meson on protons was studied by means of linearly polarized photons at forward angles in the low-energy region from threshold to $E_{\gamma}$= 2.37 GeV. The differential cross sections at $t = -|t|_{min}$ do not increase smoothly as $E_{\gamma}$ increases, but show a local maximum at around 2.0 GeV. The angular distributions demonstrate that $\phi$-mesons are photo-produced predominantly by helicity-conserving processes, and the local maximum is not likely due to unnatural-parity processes.

14 data tables

Table 1

Differential cross section as a function of T+ABS(TMIN) in the photon energy range 1.57 to 1.67 GeV.

Table 2

Differential cross section as a function of T+ABS(TMIN) in the photon energy range 1.67 to 1.77 GeV.

Table 3

Differential cross section as a function of T+ABS(TMIN) in the photon energy range 1.77 to 1.87 GeV.

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Deeply virtual and exclusive electroproduction of omega mesons.

The CLAS collaboration Morand, L. ; Dore, D. ; Garcon, M. ; et al.

Eur.Phys.J.A 24 (2005) 445-458, 2005.

Inspire Record 681604 DOI 10.17182/hepdata.43499

The exclusive omega electroproduction off the proton was studied in a large kinematical domain above the nucleon resonance region and for the highest possible photon virtuality (Q2) with the 5.75 GeV beam at CEBAF and the CLAS spectrometer. Cross sections were measured up to large values of the four-momentum transfer (-t < 2.7 GeV2) to the proton. The contributions of the interference terms sigma_TT and sigma_TL to the cross sections, as well as an analysis of the omega spin density matrix, indicate that helicity is not conserved in this process. The t-channel pi0 exchange, or more generally the exchange of the associated Regge trajectory, seems to dominate the reaction gamma* p -> omega p, even for Q2 as large as 5 GeV2. Contributions of handbag diagrams, related to Generalized Parton Distributions in the nucleon, are therefore difficult to extract for this process. Remarkably, the high-t behaviour of the cross sections is nearly Q2-independent, which may be interpreted as a coupling of the photon to a point-like object in this kinematical limit.

85 data tables

Table 1

Total cross sections and interference terms (TT and TL).

Table 2

Differential cross sections DSIG/DT for Q**2 = 1.725 GeV**2 and W = 2.77 GeV.

Table 3

Differential cross sections DSIG/DT for Q**2 = 1.752 GeV**2 and W = 2.48 GeV.

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Delbrueck scattering at energies 140-MeV to 450-MeV.

Akhmadalev, S.Z. ; Kezerashvili, G.Ya. ; Klimenko, S.G. ; et al.

BUDKER-INP-1998-51, 1998.

Inspire Record 472470 DOI 10.17182/hepdata.50144

The differential cross section of Delbr\"{u}ck scattering is measured on a bismuth germanate $Bi_4Ge_3O_{12}$ target at photon energies $140 - 450 MeV$ and scattering angles $2.6 - 16.6 mrad$. A good agreement with the theoretical results, obtained exactly in a Coulomb field, is found.

1 data table

Table 1

Axis error includes +- 1.5/1.5 contribution (Error of measurement of the initial photons intensity).

ELASTIC SCATTERING OF pi- AND K- MESONS ON PROTONS AT 43-GeV/c MOMENTUM

The SIGMA-AYaKS & Dubna-Serpukhov-Tbilisi collaborations Antipov, Yu.M. ; Batarin, V.A. ; Bezzubov, V.A. ; et al.

Sov.J.Nucl.Phys. 48 (1988) 85, 1988.

Inspire Record 253399 DOI 10.17182/hepdata.38881

None

3 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

FROM EXPONENTIAL FIT OF D(SIG)/D(T) IN RANGE 0. < ABS(T) < 1. GEV.

Study of Elastic $\pi^+ p$, $K^+ p$ and $p p$ Scattering at 250-{GeV}/$c$

The NA22 collaboration Adamus, M. ; Ajinenko, I.V. ; Agababyan, N.M. ; et al.

Phys.Lett.B 186 (1987) 223-226, 1987.

Inspire Record 246909 DOI 10.17182/hepdata.40833

Results are presented on π + p and K + p elastic scattering at 250 GeV/ c , the highest momentum so far reached for positive meson beams. The experiment (NA22) was performed with the european hybrid spectrometer. The π + p elastic cross section stays constant with energy while the K + p cross section increases.

4 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

ERRORS IN ELASTIC CROSS SECTIONS INCLUDE SYSTEMATIC ERRORS.

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