Coincidence electroproduction of single neutral pions in the resonance region at q 2 = 0.5 (GeV/ c ) 2

Latham, A. ; Allison, J. ; Booth, I. ; et al.
Nucl.Phys.B 156 (1979) 58-92, 1979.
Inspire Record 1392686 DOI 10.17182/hepdata.836

Data are presented for the reaction ep → ep π 0 at a nominal four-momentum transfer squared of 0.5 (GeV/ c ) 2 . The data were obtained using an extracted electron beam from NINA and two magnetic spectrometers for coincidence detection of the electron and proton. Details are given of the experimental method and the results are given for isobar masses in the range 1.19 – 1.73 GeV/ c 2 .

21 data tables

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Measurements of the cross-sections for the photoproduction of positive pions on hydrogen in the region of the first resonance

Freytag, D. ; Schwille, W.J. ; Wedemeyer, R.J. ;
Z.Phys. 186 (1965) 1-22, 1965.
Inspire Record 1385262 DOI 10.17182/hepdata.16671

Die differentiellen Wirkungsquerschnitte der Reaktionγ+p→π ++n wurden mit einem verbesserten Reichweiteteleskop für die Laborwinkel zwischen 20 und 160° in Abständen von 10° absolut gemessen. Die Meßp

44 data tables

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Cross sections for the reactions $e^+ e^-\to K_S^0 K_L^0$, $K_S^0 K_L^0 \pi^+\pi^-$, $K_S^0 K_S^0 \pi^+\pi^-$, and $K_S^0 K_S^0 K^+K^-$ from events with initial-state radiation

The BaBar collaboration Lees, J.P. ; Poireau, V. ; Tisserand, V. ; et al.
Phys.Rev.D 89 (2014) 092002, 2014.
Inspire Record 1287920 DOI 10.17182/hepdata.64506

We study the processes $e^+ e^-\to K_S^0 K_L^0 \gamma$, $K_S^0 K_L^0 \pi^+\pi^-\gamma$, $K_S^0 K_S^0 \pi^+\pi^-\gamma$, and $K_S^0 K_S^0 K^+K^-\gamma$, where the photon is radiated from the initial state, providing cross section measurements for the hadronic states over a continuum of center-of-mass energies. The results are based on 469 fb$^{-1}$ of data collected with the BaBar detector at SLAC. We observe the $\phi(1020)$ resonance in the $K_S^0 K_L^0$ final state and measure the product of its electronic width and branching fraction with about 3% uncertainty. We present a measurement of the $e^+ e^-\to K_S^0 K_L^0 $ cross section in the energy range from 1.06 to 2.2 GeV and observe the production of a resonance at 1.67 GeV. We present the first measurements of the $e^+ e^-\to K_S^0 K_L^0 \pi^+\pi^-$, $K_S^0 K_S^0 \pi^+\pi^-$, and $K_S^0 K_S^0 K^+K^-$ cross sections, and study the intermediate resonance structures. We obtain the first observations of \jpsi decay to the $K_S^0 K_L^0 \pi^+\pi^-$, $K_S^0 K_S^0 \pi^+\pi^-$, and $K_S^0 K_S^0 K^+K^-$ final states.

22 data tables

Cross section measurement for PHI(1020).

Mass measurement for PHI(1020).

Measurement of the PHI(1020) width.

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Study of e+e- --> p anti-p via initial-state radiation at BABAR

The BaBar collaboration Lees, J.P. ; Poireau, V. ; Tisserand, V. ; et al.
Phys.Rev.D 87 (2013) 092005, 2013.
Inspire Record 1217421 DOI 10.17182/hepdata.62678

The process e+e- --> p anti-p gamma is studied using 469 fb-1 of integrated luminosity collected with the BABAR detector at the PEP-II collider, at an e+e- center-of-mass energy of 10.6 GeV. From the analysis of the p anti-p invariant mass spectrum, the energy dependence of the cross section for e+e- --> p anti-p is measured from threshold to 4.5 GeV. The energy dependence of the ratio of electric and magnetic form factors, |G_E/G_M|, and the asymmetry in the proton angular distribution are measured for p anti-p masses below 3 GeV. We also measure the branching fractions for the decays J/psi --> p anti-p and psi(2S) --> p anti p.

1 data table

Measurement of the cross section as a function of the invariant mass of the PBAR-P system and the effective form factor for the reaction E+ E- --> PBAR P. The contributions from J/PSI and PSI(25) decaying to PBAR-P have been subtracted. The form factor error is the combined statistical and systematic.


Cross Sections for the Reactions e+e- --> K+ K- pi+pi-, K+ K- pi0pi0, and K+ K- K+ K- Measured Using Initial-State Radiation Events

The BaBar collaboration Lees, J.P. ; Poireau, V. ; Prencipe, E. ; et al.
Phys.Rev.D 86 (2012) 012008, 2012.
Inspire Record 892684 DOI 10.17182/hepdata.62222

We study the processes e+e- --> K+ K- pi+pi-gamma, K+ K- pi0pi0gamma, and K+ K- K+ K-gamma, where the photon is radiated from the initial state. About 84000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb-1 of BaBar data. The invariant mass of the hadronic final state defines the \epem center-of-mass energy, so that the K+ K- pi+pi- data can be compared with direct measurements of the e+e- --> K+ K- pi+pi- reaction. No direct measurements exist for the e+e- --> K+ K-pi0pi0 or e+e- --> K+ K-K+ K- reactions, and we present an update of our previous result with doubled statistics. Studying the structure of these events, we find contributions from a number of intermediate states, and extract their cross sections. In particular, we perform a more detailed study of the e+e- --> phi(1020)pipigamma reaction, and confirm the presence of the Y(2175) resonance in the phi(1020) f0(980) and K+K-f0(980) modes. In the charmonium region, we observe the J/psi in all three final states and in several intermediate states, as well as the psi(2S) in some modes, and measure the corresponding product of branching fraction and electron width.

8 data tables

The cross section for the reaction E+ E- --> K+ K- PI+ PI- measured with ISR data. Statistical errors only.

Cross section measurements for the reaction E+ E- --> K*(892)0 K- PI+. Statistical errors only.

Cross section measurements for the reaction E+ E- --> PHI PI+ PI-. Statistical errors only.

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Neutral Pion Electroproduction in the Resonance Region at High $Q^2$

Villano, A.N. ; Stoler, P. ; Bosted, P.E. ; et al.
Phys.Rev.C 80 (2009) 035203, 2009.
Inspire Record 823260 DOI 10.17182/hepdata.54189

The process $ep \to e^{\prime}p^{\prime}\pi^0$ has been measured at $Q^2$ = 6.4 and 7.7 \ufourmomts in Jefferson Lab's Hall C. Unpolarized differential cross sections are reported in the virtual photon-proton center of mass frame considering the process $\gamma^{\ast}p \to p^{\prime}\pi^0$. Various details relating to the background subtractions, radiative corrections and systematic errors are discussed. The usefulness of the data with regard to the measurement of the electromagnetic properties of the well known $\Delta(1232)$ resonance is covered in detail. Specifically considered are the electromagnetic and scalar-magnetic ratios $R_{EM}$ and $R_{SM}$ along with the magnetic transition form factor $G_M^{\ast}$. It is found that the rapid fall off of the $\Delta(1232)$ contribution continues into this region of momentum transfer and that other resonances

125 data tables

Differential cross sections at Q**2=6.564 GeV**2, EPSILON=0.4523, W=1.112 GeV and COS(THETA(*))=-0.9 for the small SOS spectrometer.

Differential cross sections at Q**2=6.564 GeV**2, EPSILON=0.4523, W=1.112 GeV and COS(THETA(*))=-0.7 for the small SOS spectrometer.

Differential cross sections at Q**2=6.564 GeV**2, EPSILON=0.4523, W=1.112 GeV and COS(THETA(*))=-0.5 for the small SOS spectrometer.

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Electroproduction of Eta Mesons in the S11(1535) Resonance Region at High Momentum Transfer

Dalton, M.M. ; Adams, G.S. ; Ahmidouch, A. ; et al.
Phys.Rev.C 80 (2009) 015205, 2009.
Inspire Record 783943 DOI 10.17182/hepdata.50548

The differential cross-section for the process p(e,e'p)eta has been measured at Q2 ~ 5.7 and 7.0 (GeV/c)2 for centre-of-mass energies from threshold to 1.8 GeV, encompassing the S11(1535) resonance, which dominates the channel. This is the highest momentum transfer measurement of this exclusive process to date. The helicity-conserving transition amplitude A_1/2, for the production of the S11(1535) resonance, is extracted from the data. This quantity appears to begin scaling as 1/Q3, a predicted signal of the dominance of perturbative QCD, at Q2 ~ 5 (GeV/c)2.

39 data tables

Total cross section for the lower Q**2 data as a function of W. The errors are statistics and systematic added in quadrature.

Total cross section for the higher Q**2 data as a function of W. The errors are statistics and systematic added in quadrature.

Lower Q**2 extracted differential cross section at W = 1.500 GeV and cos(theta(eta) = -0.917, -0.750 and -0.583.

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Measurements of e+ e- ---> K+ K- eta, K+ K- pi0 and K0(s) K+- pi-+ cross- sections using initial state radiation events

The BaBar collaboration Aubert, Bernard ; Bona, M. ; Boutigny, D. ; et al.
Phys.Rev.D 77 (2008) 092002, 2008.
Inspire Record 765258 DOI 10.17182/hepdata.50372

This paper reports measurements of processes: e+e- -> gamma KsK+pi-, e+e- -> gamma K+K-pi0, e+e- -> gamma phi eta, and e+e- -> gamma phi pi0. The initial state radiated photon allows to cover the hadronic final state in the energy range from thresholds up to ~4.6 GeV. The overall size of the data sample analyzed is 232 fb-1, collected by the BaBar detector running at the PEP-II e+e- storage ring. From the Dalitz plot analysis of the KsK+pi- final state, moduli and relative phase of the isoscalar and the isovector components of the e+e- -> K K*(892) cross section are determined. Parameters of phi and rho recurrences are also measured, using a global fitting procedure which exploits the interconnection among amplitudes, moduli and phases of the e+e- -> KsK+pi-, K+K-pi0, phi eta final states. The cross section for the OZI-forbidden process e+e- -> phi pi0, and the J/psi branching fractions to KK*(892) and K+K-eta are also measured.

9 data tables

The cross section for E+ E- --> K0S K+ PI- + CC with statistical errors only.

The cross section for E+ E- --> K+ K- PI0 with statistical errors only.

The cross section for E+ E- --> PHI PI0 with statistical errors only.

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The $e^+ e^-\to 2(\pi^+\pi^-)\pi^0$, 2(\pi^+\pi^-)\eta$, $K^+ K^-\pi^+\pi^-\pi^0$ and $K^+ K^-\pi^+\pi^-\eta$ Cross Sections Measured with Initial-State Radiation

The BaBar collaboration Aubert, Bernard ; Bona, M. ; Boutigny, D. ; et al.
Phys.Rev.D 76 (2007) 092005, 2007.
Inspire Record 758568 DOI 10.17182/hepdata.51824

We study the processes $e^+ e^-\to 2(\pi^+\pi^-)\pi^0\gamma$, $2(\pi^+\pi^-)\eta\gamma$, $K^+ K^-\pi^+\pi^-\pi^0\gamma$ and $K^+ K^-\pi^+\pi^-\eta\gamma$ with the hard photon radiated from the initial state. About 20000, 4300, 5500 and 375 fully reconstructed events, respectively, are selected from 232 fb$^{-1}$ of BaBar data. The invariant mass of the hadronic final state defines the effective $e^+ e^-$ center-of-mass energy, so that the obtained cross sections from the threshold to about 5 GeV can be compared with corresponding direct \epem measurements, currently available only for the $\eta\pi^+\pi^-$ and $\omega\pi^+\pi^-$ submodes of the $e^+ e^-\to 2(\pi^+\pi^-)\pi^0$ channel. Studying the structure of these events, we find contributions from a number of intermediate states, and we extract their cross sections where possible. In particular, we isolate the contribution from $e^+ e^-\to\omega(782)\pi^+\pi^-$ and study the $\omega(1420)$ and $\omega(1650)$ resonances. In the charmonium region, we observe the $J/\psi$ in all these final states and several intermediate states, as well as the $\psi(2S)$ in some modes, and we measure the corresponding branching fractions.

11 data tables

Measured cross section for E+ E- --> 2(PI+ PI-) PI0 with statistical errorsonly.

Measured cross section for E+ E- --> ETA PI+ PI- with statistical errors only.

Measured cross section for E+ E- --> OMEGA PI+ PI- with statistical errors only.

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pi0 photoproduction on the proton for photon energies from 0.675-GeV to 2.875-GeV.

Dugger, M. ; Ritchie, Barry G. ; Ball, J.P. ; et al.
Phys.Rev.C 76 (2007) 025211, 2007.
Inspire Record 749989 DOI 10.17182/hepdata.51855

Differential cross sections for the reaction $\gamma p \to p \pi^0$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.675 to 2.875 GeV. The results reported here possess greater accuracy in the absolute normalization than previous measurements. They disagree with recent CB-ELSA measurements for the process at forward scattering angles. Agreement with the SAID and MAID fits is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been extended to 3 GeV. Resonance couplings have been extracted and compared to previous determinations.

45 data tables

Differential cross section for indicent photon energy 675 MeV.

Differential cross section for indicent photon energy 725 MeV.

Differential cross section for indicent photon energy 775 MeV.

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