Date

Measurement of the beam asymmetry $\Sigma$ for $\pi^0$ and $\eta$ photoproduction on the proton at $E_\gamma = 9$ GeV

The GlueX collaboration Al Ghoul, H. ; Anassontzis, E.G. ; Austregesilo, A. ; et al.
No Journal Information, 2017.
Inspire Record 1511149 DOI 10.17182/hepdata.76745

We report measurements of the photon beam asymmetry $\Sigma$ for the reactions $\vec{\gamma}p\to p\pi^0$ and $\vec{\gamma}p\to p\eta $ from the GlueX experiment using a 9 GeV linearly polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous $\pi^0$ measurements and are the first $\eta$ measurements in this energy regime. The results are compared with theoretical predictions based on $t$-channel, quasi-particle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models.

2 data tables

Measurement of the beam asymmetry $\Sigma$ for $\pi^0$ photoproduction on the proton at $E_\gamma = 9$ GeV. The uncorrelated systematic errors (syst) are given in the table below along with a correlated normalization uncertainty (norm) of 3.6% due to the beam polarization.

Measurement of the beam asymmetry $\Sigma$ for $\eta$ photoproduction on the proton at $E_\gamma = 9$ GeV. The uncorrelated systematic errors (syst) are given in the table below along with a correlated normalization uncertainty (norm) of 3.6% due to the beam polarization.


Eta photoproduction on the proton for photon energies from 0.75-GeV to 1.95-GeV

The CLAS collaboration Dugger, M. ; Ritchie, B.G. ; Ball, J. ; et al.
Phys.Rev.Lett. 89 (2002) 222002, 2002.
Inspire Record 603904 DOI 10.17182/hepdata.19406
6 data tables

Cross sections for photon energies 0.775 to 0.925 GeV.

Cross sections for photon energies 0.975 to 1.125 GeV.

Cross sections for photon energies 1.175 to 1.325 GeV.

More…

Study of the $\gamma p -> \eta p$ reaction with the Crystal Ball detector at the Mainz Microtron(MAMI-C)

The Crystal Ball at MAMI collaboration McNicoll, E.F. ; Prakhov, S. ; Strakovsky, I.I. ; et al.
Phys.Rev. C82 (2010) 035208, 2010.
Inspire Record 860725 DOI 10.17182/hepdata.56733

The gp-->etap reaction has been measured with the Crystal Ball and TAPS multiphoton spectrometers in the energy range from the production threshold of 707 MeV to 1.4 GeV (1.49 =< W >= 1.87 GeV). Bremsstrahlung photons produced by the 1.5-GeV electron beam of the Mainz Microtron MAMI-C and momentum analyzed by the Glasgow Tagging Spectrometer were used for the eta-meson production. Our accumulation of 3.8 x 10^6 gp-->etap-->3pi0p-->6gp events allows a detailed study of the reaction dynamics. The gp-->etap differential cross sections were determined for 120 energy bins and the full range of the production angles. Our data show a dip near W = 1680 MeV in the total cross section caused by a substantial dip in eta production at forward angles. The data are compared to predictions of previous SAID and MAID partial-wave analyses and to thelatest SAID and MAID fits that have included our data.

121 data tables

Total cross section for the reaction GAMMA P --> ETA P.

Differential cross section for the reaction GAMMA P --> ETA P at a photon energy of 710.4 MeV. The errors in the table are statistical only and there is an overall systematic uncertainty of 4.3 PCT.

Differential cross section for the reaction GAMMA P --> ETA P at a photon energy of 714.5 MeV. The errors in the table are statistical only and there is an overall systematic uncertainty of 4.3 PCT.

More…

Photoproduction of eta and eta-prime mesons off protons

The CBELSA/TAPS collaboration Crede, V. ; McVeigh, A. ; Anisovich, A.V. ; et al.
Phys.Rev. C80 (2009) 055202, 2009.
Inspire Record 836340 DOI 10.17182/hepdata.53229

Total and differential cross sections for $\eta$ and $\eta ^\prime$ photoproduction off the proton have been determined with the CBELSA/TAPS detector for photon energies between 0.85 and 2.55 GeV. The $\eta$ mesons are detected in their two neutral decay modes, $\eta\to\gamma\gamma$ and $\eta\to 3\pi^0\to 6\gamma$, and for the first time, cover the full angular range in $\rm cos \theta_{cm}$ of the $\eta$ meson. These new $\eta$ photoproduction data are consistent with the earlier CB-ELSA results. The $\eta ^\prime$ mesons are observed in their neutral decay to $\pi^0\pi^0\eta\to 6\gamma$ and also extend the coverage in angular range.

56 data tables

Differential cross section for ETA production at incident photon energy 0.850 to 0.900 GeV.

Differential cross section for ETA production at incident photon energy 0.900 to 0.950 GeV.

Differential cross section for ETA production at incident photon energy 0.950 to 1.000 GeV.

More…

Differential cross s ections for the reactions gamma p ---> p eta and gamma p ---> p eta-prime

The CLAS collaboration Williams, M. ; Krahn, Z. ; Applegate, D. ; et al.
Phys.Rev. C80 (2009) 045213, 2009.
Inspire Record 830257 DOI 10.17182/hepdata.52983

High-statistics differential cross sections for the reactions gamma p -> p eta and gamma p -> p eta-prime have been measured using the CLAS at Jefferson Lab for center-of-mass energies from near threshold up to 2.84 GeV. The eta-prime results are the most precise to date and provide the largest energy and angular coverage. The eta measurements extend the energy range of the world's large-angle results by approximately 300 MeV. These new data, in particular the eta-prime measurements, are likely to help constrain the analyses being performed to search for new baryon resonance states.

104 data tables

Differential cross section for the W range 1.68 to 1.69 GeV.

Differential cross section for the W range 1.69 to 1.70 GeV.

Differential cross section for the W range 1.70 to 1.71 GeV.

More…

Quasi-free photoproduction of eta-mesons of the neutron

The CBELSA TAPS collaborations Jaegle, I. ; Mertens, T. ; Anisovich, A.V. ; et al.
Phys.Rev.Lett. 100 (2008) 252002, 2008.
Inspire Record 784698 DOI 10.17182/hepdata.50884

Quasi-free photoproduction of eta-mesons off nucleons bound in the deuteron has been measured with the CBELSA/TAPS detector for incident photon energies up to 2.5 GeV at the Bonn ELSA accelerator. The eta-mesons have been detected in coincidence with recoil protons and recoil neutrons, which allows a detailed comparison of the quasi-free n(gamma,eta)n and p(gamma,eta)p reactions. The excitation function for eta-production off the neutron shows a pronounced bump-like structure at W=1.68 GeV (E_g ~ 1 GeV), which is absent for the proton.

22 data tables

Measured value of the quasi-free eta cross section off protons and neutrons as a function of incident photon energy.

Ratio of the measured quasi-free neutron to proton cross sections as a function of incident photon energy.

Measured angular distribution for an incident photon energy of 0.700 GeV.

More…

Measurement of eta photoproduction on the proton from threshold to 1500-MeV

The GRAAL collaboration Bartalini, O. ; Bellini, V. ; Bocquet, J.P. ; et al.
Eur.Phys.J. A33 (2007) 169-184, 2007.
Inspire Record 755415 DOI 10.17182/hepdata.51526

Beam asymmetry and differential cross section for the reaction gamma+p->eta+p were measured from production threshold to 1500 MeV photon laboratory energy. The two dominant neutral decay modes of the eta meson, eta->2g and eta->3pi0, were analyzed. The full set of measurements is in good agreement with previously published results. Our data were compared with three models. They all fit satisfactorily the results but their respective resonance contributions are quite different. The possible photoexcitation of a narrow state N(1670) was investigated and no evidence was found.

45 data tables

Measured beam asymmetry at photon energy 724 MeV as a function of the ETA centre of mass angle.

Measured beam asymmetry at photon energy 761 MeV as a function of the ETA centre of mass angle.

Measured beam asymmetry at photon energy 810 MeV as a function of the ETA centre of mass angle.

More…

Eta photoproduction on the proton revisited: Evidence for a narrow N(1685) resonance?

Kuznetsov, V. ; Polyakov, M. ; Boiko, T. ; et al.
No Journal Information, 2007.
Inspire Record 745642 DOI 10.17182/hepdata.41745

Revised analysis of $\Sigma$ beam asymmetry for $\eta$ photoproduction on the free proton reveals a resonant structure at $W\sim 1.69$ GeV. Comparison of experimental data with multipole decomposition based on the E429 solution of the SAID partial wave analysis and including narrow states, suggests a narrow ($\Gamma \leq 15$ MeV) resonance. Possible candidates are $P_{11}$, $P_{13}$, or $D_{13}$ resonances. The result is considered in conjunction with the recent evidence for a bump-like structure at $W\sim 1.67 - 1.68$ GeV in quasi-free $\eta$ photoproduction on the neutron.

5 data tables

Measured beam asymmetry for a mean scattering angle of 43 degrees.

Measured beam asymmetry for a mean scattering angle of 65 degrees.

Measured beam asymmetry for a mean scattering angle of 85 degrees.

More…

Evidence for a narrow structure at W~1.68-GeV in eta photoproduction on the neutron

The GRAAL collaboration Kuznetsov, Viacheslav ; Churikova, S. ; Gervino, G. ; et al.
Phys.Lett. B647 (2007) 23-29, 2007.
Inspire Record 720508 DOI 10.17182/hepdata.26995

New results on quasi-free $\eta$ photoproduction on the neutron and proton bound in a deuteron target are presented. The $\gamma n \to \eta n$ quasi-free cross section reveals a bump-like structure which is not seen in the cross section on the proton. This structure may signal the existence of a relatively narrow ($M\sim 1.68$ GeV, $\Gamma \leq 30$ MeV) baryon state.

6 data tables

Quasi free differential cross section for the reaction GAMMA N --> ETA N at COS(THETA(CM)) from -0.9 to -0.5.

Quasi free differential cross section for the reaction GAMMA N --> ETA N at COS(THETA(CM)) from -0.3 to 0.1.

Quasi free differential cross section for the reaction GAMMA N --> ETA N at COS(THETA(CM)) from 0.1 to 0.5.

More…

Measurement of the beam asymmetry in eta-photoproduction off the proton

The CBELSA TAPS collaborations Elsner, D. ; Anisovich, A.V. ; Anton, G. ; et al.
Eur.Phys.J. A33 (2007) 147-155, 2007.
Inspire Record 744568 DOI 10.17182/hepdata.43430

The beam asymmetry, $\Sigma$, was measured at ELSA in the reaction $\vec \gamma p \to \eta p$ using linearly polarised tagged photon beams, produced by coherent bremsstrahlung off a diamond. The crystal was oriented to provide polarised photons in the energy range $E_\gamma = 800$ to 1400 MeV with the maximum polarisation of $P_\gamma = 49$ % obtained at 1305 MeV. Both dominant decay modes of the $\eta$ into two photons and $3\pi^0$ were used to extract the beam asymmetry from the azimuthal modulation of the cross section. The measurements cover the angular range $\Theta_\text{cm}\simeq 50$ -- 150 degrees. Large asymmetries up to 80 % are observed, in agreement with a previous measurement. The eta-MAID model and the Bonn--Gatchina partial wave analysis describe the measurements, but the required partial waves differ significantly.

6 data tables

Photon asymmetry for eta photoproduction at incident photon energy of 850 MeV.

Photon asymmetry for eta photoproduction at incident photon energy of 950 MeV.

Photon asymmetry for eta photoproduction at incident photon energy of 1050 MeV.

More…

Photoproduction of eta mesons off protons for 0.75-GeV < E(gamma) < 3-GeV

The CB-ELSA collaboration Crede, Volker ; Bartholomy, Olivia ; Anisovich, A. ; et al.
Phys.Rev.Lett. 94 (2005) 012004, 2005.
Inspire Record 633776 DOI 10.17182/hepdata.41904

Total and differential cross sections for the reaction p(gamma, eta)p have been measured for photon energies in the range from 750 MeV to 3 GeV. The low-energy data are dominated by the S11 wave which has two poles in the energy region below 2 GeV. Eleven nucleon resonances are observed in their decay into p eta. At medium energies we find evidence for a new resonance N(2070)D15 with (mass, width) = (2068+-22, 295+-40) MeV. At photon energies above 1.5 GeV, a strong peak in forward direction develops, signalling the exchange of vector mesons in the t channel.

10 data tables

Total cross section determined by summing the angular bins and extrapolating outside the angular range of the experiment.

Differential cross section as a function of c.m. angle for the photon energy range 750 to 950 GeV.

Differential cross section as a function of c.m. angle for the photon energy range 950 to 1150 GeV.

More…

The Polarized Target Asymmetry in Photoproduction of $\Eta$ Mesons From Protons at 4-{GeV}

Bussey, P.J. ; Raine, C. ; Rutherglen, J.G. ; et al.
Nucl.Phys. B185 (1981) 269-273, 1981.
Inspire Record 155784 DOI 10.17182/hepdata.34276
1 data table

No description provided.


Measurements of Cross-section Asymmetry by Polarized Photons and Models of Eta0 Meson Photoproduction in the Energy Range $E_\gamma = 1$-{GeV} to 2-{GeV}

Vartapetian, G.A. ; Piliposian, S.E. ;
Sov.J.Nucl.Phys. 32 (1980) 804, 1980.
Inspire Record 154948 DOI 10.17182/hepdata.18828
20 data tables

No description provided.

Axis error includes +- 16/16 contribution.

No description provided.

More…

PHOTOPRODUCTION OF eta0 MESONS AT 4-Gev

Bellenger, D. ; Deutsch, S. ; Luckey, David ; et al.
Phys.Rev.Lett. 21 (1968) 1205, 1968.
Inspire Record 53018 DOI 10.17182/hepdata.21703
1 data table

Axis error includes +- 0.0/0.0 contribution (?////).


Differential cross-section and recoil proton polarization of eta-meson photoproduction at 890 mev

Hongoh, M. ; Kikuchi, K. ; Kobayakawa, H. ; et al.
Lett.Nuovo Cim. 2S2 (1971) 317-320, 1971.
Inspire Record 70913 DOI 10.17182/hepdata.37410
2 data tables

No description provided.

No description provided.


Photoproduction of eta mesons from hydrogen

Dewire, J. ; Gittelman, B. ; Loe, R. ; et al.
Phys.Lett. B37 (1971) 326-328, 1971.
Inspire Record 75928 DOI 10.17182/hepdata.28354
2 data tables

Axis error includes +- 9.4/9.4 contribution.

Axis error includes +- 9.4/9.4 contribution.


Photoproduction of eta meson between threshold and 900 mev

Delcourt, B. ; Lefrancois, J. ; Perez-Y-Jorba, J.P. ; et al.
Phys.Lett. B29 (1969) 75-78, 1969.
Inspire Record 56793 DOI 10.17182/hepdata.28963
6 data tables

No description provided.

No description provided.

No description provided.

More…

The photoproduction of eta mesons at small angles

Booth, P.S.L. ; Barton, J.S. ; Carroll, L.J. ; et al.
Nucl.Phys. B25 (1971) 510-518, 1971.
Inspire Record 68819 DOI 10.17182/hepdata.33806
4 data tables

No description provided.

No description provided.

No description provided.

More…

RECOIL PROTON POLARIZATION IN ETA PHOTOPRODUCTION

Heusch, C.A. ; Prescott, C.Y. ; Rochester, L.S. ; et al.
Phys.Rev.Lett. 25 (1970) 1381, 1970.
Inspire Record 61494 DOI 10.17182/hepdata.21581
1 data table

No description provided.


PHOTOPRODUCTION OF ETA MESONS FROM 950-MeV TO 1100-MeV

Heusch, C.A. ; Prescott, C.Y. ; Bloom, Elliott D. ; et al.
Phys.Rev.Lett. 17 (1966) 573, 1966.
Inspire Record 50081 DOI 10.17182/hepdata.21826
1 data table

No description provided.


Differential cross-sections for the photoproduction of eta mesons from protons near 2 gev

Booth, P.S.L. ; Carroll, L.J. ; Holt, J.R. ; et al.
Nucl.Phys. B71 (1974) 211-216, 1974.
Inspire Record 94714 DOI 10.17182/hepdata.32321
2 data tables

No description provided.

THESE DATA ARE A REANALYSIS OF THOSE REPORTED IN P. S. L. BOOTH ET AL., NP B25, 510 (1971). THE CORRECTED RESULTS ARE IN GENERAL ABOUT TWICE THE OLD VALUES.


Photoproduction of eta-mesons on hydrogen at photon energies between 1.5 and 2.2 gev

Christ, A. ; Husmann, D. ; Jansen, W. ; et al.
Lett.Nuovo Cim. 8S2 (1973) 1039-1043, 1973.
Inspire Record 86582 DOI 10.17182/hepdata.37327
1 data table

APPROXIMATELY CONSTANT MOMENTUM TRANSFER.


Cross-Section Asymmetry of eta Mesons Photoproduction by Polarized Photons in the Resonance Region

Abramian, L.O. ; Avakian, R.O. ; Aganyants, Aleksandr O. ; et al.
Pisma Zh.Eksp.Teor.Fiz. 25 (1977) 597-600, 1977.
Inspire Record 124683 DOI 10.17182/hepdata.39787
1 data table

No description provided.


The Polarized Beam Asymmetry in Photoproduction of eta Mesons from Protons at 2.5-GeV and 3.0-GeV

Bussey, P.J. ; Raine, C. ; Rutherglen, J.G. ; et al.
Phys.Lett. B61 (1976) 479-482, 1976.
Inspire Record 108515 DOI 10.17182/hepdata.27687
2 data tables

No description provided.

No description provided.


The photoproduction of eta-mesons between 950 mev and 2.2 gev

Booth, P.S.L. ; Butler, M.F. ; Carroll, L.J. ; et al.
Lett.Nuovo Cim. 2S1 (1969) 66-70, 1969.
Inspire Record 58277 DOI 10.17182/hepdata.37407
1 data table

No description provided.