Date

Photoproduction of meson pairs: First measurement of the polarization observable I^s

The CBELSA & TAPS collaborations Gutz, E. ; Sokhoyan, V. ; van Pee, H. ; et al.
Phys.Lett.B 687 (2010) 11-15, 2010.
Inspire Record 840021 DOI 10.17182/hepdata.42248

The polarization observable I^s, a feature exclusive to the acoplanar kinematics of multi-meson final states produced via linearly polarized photons, has been measured for the first time. Results for the reaction g p -> p pi0 eta are presented for incoming photon energies between 970 MeV and 1650 MeV along with the beam asymmetry I^c. The comparably large asymmetries demonstrate a high sensitivity of I^s to the dynamics of the reaction. Fits using Bonn-Gatchina partial wave analysis demonstrate that the new polarization observables carry significant information on the contributing partial waves.

18 data tables match query

Measured beam asymmetry I_S as a function of the angle between the reaction plane and the plane of the two final state particles with the the proton as the recoiling particle for the cm energy range 1642 to 1770 MeV.

Measured beam asymmetry I_S as a function of the angle between the reaction plane and the plane of the two final state particles with the the proton as the recoiling particle for the cm energy range 1770 to 1898 MeV.

Measured beam asymmetry I_S as a function of the angle between the reaction plane and the plane of the two final state particles with the the proton as the recoiling particle for the cm energy range 1898 to 1994 MeV.

More…

Photoproduction of $\omega$ mesons off protons and neutrons

The CBELSA/TAPS collaboration Dietz, F. ; Metag, V. ; Anisovich, A.V. ; et al.
Eur.Phys.J.A 51 (2015) 6, 2015.
Inspire Record 1340913 DOI 10.17182/hepdata.69767

ω photoproduction off hydrogen and deuterium has been studied with the tagged photon beam of the ELSA accelerator in Bonn for photon energies up to 2.0 GeV. The ω meson has been identified via the ω → π$^{0}$ γ → γγγ decay mode, using the combined setup of the Crystal Barrel/TAPS detector systems. Both inclusive and exclusive analyses have been carried out. Differential and total cross-sections have been derived for ω mesons produced off free protons and off protons and neutrons bound in deuterium. The cross-section for the production off the bound neutron is found to be a factor of ≈ 1.3 larger than the one off the bound proton in the incident beam energy region 1.2 GeV < E$_{γ}$ < 1.6 GeV. For higher incident beam energies this factor goes down to ≈ 1.1 at 2.0 GeV. The cross-sections of this work have been used as normalization for transparency ratio measurements.

85 data tables match query

Differential cross-sections of $\omega$ mesons produced off the free proton versus $\cos(\theta^\omega_{\mathrm{c.m.}})$ and versus the momentum transfer to the nucleon, $t$, for incident photon energy $E_\gamma$ = 1.125-1.150 GeV.

Differential cross-sections of $\omega$ mesons produced off the free proton versus $\cos(\theta^\omega_{\mathrm{c.m.}})$ and versus the momentum transfer to the nucleon, $t$, for incident photon energy $E_\gamma$ = 1.150-1.175 GeV.

Differential cross-sections of $\omega$ mesons produced off the free proton versus $\cos(\theta^\omega_{\mathrm{c.m.}})$ and versus the momentum transfer to the nucleon, $t$, for incident photon energy $E_\gamma$ = 1.175-1.200 GeV.

More…

Measurement of the Helicity Asymmetry $E$ for the reaction $ \gamma p\to \pi^0 p$

The CBELSA/TAPS collaboration Gottschall, M. ; Afzal, F. ; Anisovich, A.V. ; et al.
Eur.Phys.J.A 57 (2021) 40, 2021.
Inspire Record 1731795 DOI 10.17182/hepdata.100433

A measurement of the double-polarization observable $E$ for the reaction $\gamma p\to \pi^0 p$ is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$_4$H$_9$OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from $E_\gamma =600$~MeV to $E_\gamma =2310$~MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.

1 data table match query

Double-polarization observable E for different beam energies from 600 to 2310 MeV


Polarization observables in double neutral pion photoproduction

The CBELSA/TAPS collaboration Seifen, T. ; Hartmann, J. ; Afzal, F. ; et al.
2022.
Inspire Record 2106042 DOI 10.17182/hepdata.137817

Measurements of target asymmetries and double-polarization observables for the reaction $\gamma p\to p\pi^0\pi^0$ are reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility (Bonn University) using the Bonn frozen-spin butanol (C$_4$H$_9$OH) target, which provided transversely polarized protons. Linearly polarized photons were produced via bremsstrahlung off a diamond crystal. The data cover the photon energy range from $E_{\gamma}$=650 MeV to $E_{\gamma}$=2600 MeV and nearly the complete angular range. The results have been included in the BnGa partial wave analysis. Experimental results and the fit agree very well. Observed systematic differences in the branching ratios for decays of $N^*$ and $\Delta^*$ resonances are attributed to the internal structure of these excited nucleon states. Resonances which can be assigned to SU(6)$\times$O(3) two-oscillator configurations show larger branching ratios to intermediate states with non-zero intrinsic orbital angular momenta than resonances assigned to one-oscillator configurations.

24 data tables match query

Target asymmetry for $\pi^0\pi^0$ as a function of the polar angle for bins of the incident photon energy in the range of $E_\gamma$ = 650-2600 MeV.

Target asymmetry for $\pi^0\pi^0$ as a function of the $\pi^0\pi^0$ invariant mass for bins of the incident photon energy in the range of $E_\gamma$ = 650-2600 MeV.

Target asymmetry for $\pi^0\pi^0$ as a function of the $\phi^*$ angle for bins of the incident photon energy in the range of $E_\gamma$ = 650-2600 MeV.

More…

Measurement of the beam asymmetry $\Sigma$ in $\pi^°\eta$ production off the proton with the CBELSA/TAPS experiment

The CBELSA collaboration Gutz, E. ; Sokhoyan, V. ; van Pee, H. ; et al.
Eur.Phys.J.A 35 (2008) 291-293, 2008.
Inspire Record 788569 DOI 10.17182/hepdata.54889

In photoproduction experiments, a large number of final states yielding various resonance contributions are accessible. To extract resonance parameters via partial-wave analysis not only the measurement of differential cross-sections is necessary, but also the determination of polarization observables. At the electron accelerator ELSA (Bonn) the coherent bremsstrahlung method was used to generate a linearly polarized photon beam. Using the CBELSA/TAPS detector setup, the beam asymmetry Σ in the reaction γp → pπ 0 η was determined as a function of various masses and angles for photon energies between 970MeV and 1650MeV.

12 data tables match query

Measured beam asymmetry as a function of the cosine of the scattered proton angle for beam energies 0.970 to 1.200 GeV.

Measured beam asymmetry as a function of the cosine of the scattered proton angle for beam energies 1.200 to 1.450 GeV.

Measured beam asymmetry as a function of the cosine of the scattered proton angle for beam energies 1.450 to 1.650 GeV.

More…

Resonances in anti-p p --> f2(1270) pi.

The Crystal Barrel collaboration Anisovich, A.V. ; Nikonov, V.A. ; Sarantsev, A.V. ; et al.
Phys.Lett.B 452 (1999) 187-193, 1999.
Inspire Record 501658 DOI 10.17182/hepdata.28093

We present data on p ̄ p→3π 0 at nine p̄ momenta from 600 to 1940 MeV/c. This process is dominated by the f 2 (1270) π 0 channel, where we observe I =1 resonances with the following masses and widths: 4 ++ (2260±15), Γ =180±20 MeV, 4 ++ (2005±25), Γ =360±80 MeV, 3 ++ (2310±40), Γ =180 +120 −60 MeV, 3 ++ (2070±20), Γ =170±40 MeV, 2 ++ (2280±30), Γ =280±50 MeV, 2 ++ (2100 +10 −30 ), Γ =360 +40 −100 MeV, 1 ++ (2100±20), Γ =300 +30 −60 MeV, and 1 ++ (2340±40), Γ =230±70 MeV.

1 data table match query

No description provided.


Study of anti-p p --> pi0 pi0 eta from 600-MeV/c to 1940-MeV/c.

The Crystal Barrel collaboration Anisovich, A.V. ; Nikonov, V.A. ; Sarantsev, A.V. ; et al.
Phys.Lett.B 452 (1999) 180-186, 1999.
Inspire Record 501657 DOI 10.17182/hepdata.28094

Antiproton-proton annihilation into π 0 π 0 η has been studied with incident beam momenta of 0.6 to 1.94 GeV/c. The main aim is to look for resonances formed by p ̄ p and decaying into π 0 π 0 η . Resonances observed are: two 4 ++ resonances with mass and width (M, Γ ) at (2044, 208) MeV and (2320±30, 220±30) MeV; three 2 ++ resonances at (2020±50, 220±70) MeV, (2240±40, 170±50) MeV and (2370±50, 320±50) MeV; two 3 ++ resonances at (2000±40, 250±40) MeV and (2280±30, 210±30) MeV; a 1 ++ resonance at (2340±40, 340±40) MeV; and two 2 −+ resonances at (2040±40, 190±40) MeV and (2300±40, 270±40) MeV.

1 data table match query

No description provided.


Resonances formed by anti-p p and decaying into pi0 pi0 eta for masses 1960-MeV to 2410-MeV.

Anisovich, A.V. ; Baker, C.A. ; Batty, C.J. ; et al.
Nucl.Phys.A 651 (1999) 253-276, 1999.
Inspire Record 504411 DOI 10.17182/hepdata.36177

Data on pbar-b annihilation in flight into pizero-pizero-eta are presented for nine beam momenta 600 to 1940 MeV/c. The strongest four intermediate states are found to be f_2(1270)-eta, a_2(1320)-pi, sigma-eta and a_0(980)-pi. Partial wave analysis is performed mainly to look for resonances formed by pbar-p and decaying into pizero-pizero-eta through these intermediate states. There is evidence for the following s-channel I = 0 resonances : two 4^{++} resonances with mass and width (M,Gamma) at (2044, 208) MeV and (2320+-30, 220+-30) MeV/ three 2^{++} resonances at (2020+-50, 200+-70) MeV, (2240+-40, 170+-50) MeV and (2370+-50, 320+-50) MeV/ two 3^{++} resonances at (2000+-40, 250+-40) MeV and (2280+-30, 210+-30) MeV/ a 1^{++} resonance at (2340+-40, 340+-40) MeV/ and two 2^{-+} resonances at (2040+-40, 190+-40) MeV and (2300+-40, 270+-40) MeV.

1 data table match query

No description provided.


Neutral pion photoproduction off protons in the energy range 0.3-GeV < E(gamma) < 3-GeV.

The CB-ELSA collaboration Bartholomy, O. ; Crede, V. ; van Pee, H. ; et al.
Phys.Rev.Lett. 94 (2005) 012003, 2005.
Inspire Record 654179 DOI 10.17182/hepdata.41902

Single pi0 photoproduction has been studied with the CB-ELSA experiment at Bonn using tagged photon energies between 0.3 and 3.0 GeV. The experimental setup covers a very large solid angle of about 98% of 4 pi. Differential cross sections (d sigma)/(d Omega) have been measured. Complicated structures in the angular distributions indicate a variety of different resonances being produced in the s channel intermediate state gamma p --> N* (Delta*) --> p pi0. A combined analysis including the data presented in this letter along with other data sets reveals contributions from known resonances and evidence for a new resonance N(2070)D15.

14 data tables match query

Total cross section for GAMMA P --> P PI0 obtained by integration of the angular distributions and extrapolation into the forward and backward regions using the PWA result.

Differential cross section as a function of c.m. angle for the photon energy range 300 to 425 GeV.

Differential cross section as a function of c.m. angle for the photon energy range 425 to 550 GeV.

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.A 33 (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 match query

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…