Measurements of the magnetic form factor of the proton in the timelike region at large momentum transfer.

The E835 collaboration Ambrogiani, M. ; Bagnasco, S. ; Baldini, W. ; et al.
Phys.Rev.D 60 (1999) 032002, 1999.
Inspire Record 496464 DOI 10.17182/hepdata.42105

The cross section for the reaction p¯p→e+e− has been measured at s=8.8, 10.8, 12.4, 13.1, and 14.4 GeV2 by Fermilab experiment E835. A non-magnetic spectrometer is used to identify the e+e− final states generated by the antiproton beam intersecting an internal hydrogen gas jet target. From the analysis of the 144 observed events, new high-precision measurements of the proton magnetic form factor for timelike momentum transfers are obtained.

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Study of the gamma gamma decays of the chi(c2) (1**3 P(2)) and chi(c0) (1**3 P(0)) charmonium resonances

Ambrogiani, M. ; Argiro, S. ; Bagnasco, S. ; et al.
Phys.Rev.D 62 (2000) 052002, 2000.
Inspire Record 531059 DOI 10.17182/hepdata.3517

We report the branching ratios of the χc2(13P2) and χc0(13P0) charmonium resonances to two photons using event samples collected by Fermilab experiment E835 in the reactions p¯p→χc2(13P2)[χc0(13P0)]. Our result for the χc2 is B(χc2→γγ)=(1.35±0.25±0.12)×10−4. We set a 95% upper limit for the χc0 branching ratio B(χc0→γγ) at 2.09×10−4.

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Measurements of the magnetic form-factor of the proton for timelike momentum transfers

Andreotti, M ; Bagnasco, S ; Baldini, W ; et al.
Phys.Lett.B 559 (2003) 20-25, 2003.
Inspire Record 617594 DOI 10.17182/hepdata.27006

Fermilab experiment E835 has measured the cross section for the reaction p ̄ p→e + e − at s =11.63, 12.43, 14.40 and 18.22 GeV 2 . From the analysis of the 66 observed events new high-precision measurements of the proton magnetic form factor are obtained.

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p p Interactions at 303-GeV/c: Multiplicity and Total Cross-Section.

Dao, F.T. ; Gordon, D. ; Lach, J. ; et al.
Phys.Rev.Lett. 29 (1972) 1627-1630, 1972.
Inspire Record 73776 DOI 10.17182/hepdata.21429

In an exposure of the 30-in. hydrogen bubble chamber to a 303−GeVc proton beam, 2245 interactions have been observed. The measured total cross section is 39.0±1.0 mb and the average charged particle multiplicity 〈nch〉=8.86±0.16.

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A Search for Direct Photon Production in 200 GeV/c and 300 GeV/c Proton - Beryllium Interactions

Baltrusaitis, R.M. ; Binkley, Morris E. ; Cox, B. ; et al.
Phys.Lett.B 88 (1979) 372-378, 1979.
Inspire Record 142314 DOI 10.17182/hepdata.27292

A search has been made for direct photon production in pBe interactions at 200 and 300 GeV/ c over the kinematic region 1.5 < P ⊥ < 4.0 GeV/ c and −0.7 < X F < 0 (90° < θ cms < 160°). An excess of single photons above that which is predicted from the measured π 0 and η 0 production is observed. Theratio of γ / π 0 production is calculated assuming that the excess arises from direct photon production. We find that this ratio averages 0.070 ± 0.025 (including systematic errors) in this region of X F and P ⊥ for our 200 and 300 GeV/ c data. We have used our measured value of the η / π 0 ratio of 0.47 ± 0.10 in the determination of the γ / π 0 ratio. The variation of γ / π 0 with X F , P ⊥ , X R and θ cms presented.

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Inclusive $\pi^0$ Production Over Large $X_{\perp}$ Transverse and $X_F$ Ranges in 200 GeV/c, 300 GeV/c and 400 GeV/c Proton - Beryllium Interactions

Baltrusaitis, R.M. ; Binkley, Morris E. ; Cox, B. ; et al.
Phys.Rev.Lett. 44 (1980) 122, 1980.
Inspire Record 141769 DOI 10.17182/hepdata.42706

Measurements of recognized π0 production in p-Be collisions for 0.1<X⊥<0.5 and −0.8<XF<0.0 at 200, 300, and 400 GeV/c are presented. These invariant cross sections are fitted by Edσdp3=A(1−XR)MP⊥−N over this range of X⊥ and XF with M=4.88±0.14 and N=8.90±0.10 independent of energy. No significant evidence for breaking of this scaling is observed over this large kinematic region at these energies.

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$pp$ Interactions at 300-GeV/c: Measurement of the Charged Multiplicity, Total and Elastic Cross-Sections

Firestone, A. ; Davidson, V. ; Lam, D. ; et al.
Phys.Rev.D 10 (1974) 2080, 1974.
Inspire Record 1242 DOI 10.17182/hepdata.25012

In a 35 000-picture exposure of the 30-in. hydrogen bubble chamber to a 300-GeV/c proton beam at the Fermi National Accelerator Laboratory, 10054 interactions have been observed. The measured total cross section is $40.68 \pm 0.55$ mb, the elastic cross section is $7.89 \pm 0.52$ mb, and the average charged-particle multiplicity for inelastic events is $8.S0 \pm 0.12$.

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psi production and anti-p N and pi- N interactions at 125-GeV/c and a determination of the gluon structure functions of the anti-p and the pi-

Tzamarias, S. ; Katsanevas, S. ; Kourkoumelis, C. ; et al.
Phys.Rev.D 48 (1993) 5067-5080, 1993.
Inspire Record 297586 DOI 10.17182/hepdata.22578

We have measured the cross section for production of ψ and ψ′ in p¯ and π− interactions with Be, Cu, and W targets in experiment E537 at Fermilab. The measurements were performed at 125 GeV/c using a forward dimuon spectrometer in a closed geometry configuration. The gluon structure functions of the p¯ and π− have been extracted from the measured dσdxF spectra of the produced ψ's. From the p¯W data we obtain, for p¯, xG(x)=(2.15±0.7)[1−x](6.83±0.5)[1+(5.85±0.95)x]. In the π− case, we obtain, from the W and the Be data separately, xG(x)=(1.49±0.03)[1−x](1.98±0.06) (for π−W), xG(x)=(1.10±0.10)[1−x](1.20±0.20) (for π−Be).

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Nuclear Target Effects in J/psi Production in 125-GeV/c anti-Proton and pi- Interactions

Katsanevas, S. ; Kourkoumelis, C. ; Markou, A. ; et al.
Phys.Rev.Lett. 60 (1988) 2121, 1988.
Inspire Record 252806 DOI 10.17182/hepdata.20104

The production of the Jψ resonance in 125-GeV/c p¯ and φ− interactions with Be, Cu, and W targets has been measured. The cross section per nucleon for Jψ production is suppressed in W interactions relative to the lighter targets, especially at large values of Feynman x, which is opposite to the expectation from the various explanations of the European Muon Collaboration effect. Models incorporating modifications of the gluon structure functions in heavy targets show qualitative agreement with the data.

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Continuum Dimuon Production in anti-p W Collisions at 125-GeV/c

Anassontzis, E. ; Katsanevas, S. ; Kostarakis, P. ; et al.
Phys.Rev.Lett. 54 (1985) 2572, 1985.
Inspire Record 213694 DOI 10.17182/hepdata.20379

The cross section for the reaction p¯N→μ+μ−X with muon pairs in the mass range 4<M<9 GeV/c2 and xF>0 was measured to be σ=0.104±0.005±0.008 nb/nucleon. The distributions dσdxF and M3dσdM were compared to the QCD-improved Drell-Yan model and to calculations including first-order QCD corrections, with use of deep-inelastic structure functions. Excellent agreement with the data was obtained if the calculations were multiplied by factors of 2.45 and 1.41, respectively.

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