HEPData Search

Angular distributions for π0 photoproduction from hydrogen at energies between 660 and 800 MeV and proton center-of-mass angles from 0° to 140° have been measured and analyzed. Some variation from a pure d32 state is seen in the resonance region. A possible high-momentum-transfer enhancement of the cross section is discussed.

13 data tables match query

Table 1

Axis error includes +- 0.0/0.0 contribution (3 TO 10////).

Table 2

Axis error includes +- 0.0/0.0 contribution (3 TO 10////).

Table 3

Axis error includes +- 0.0/0.0 contribution (3 TO 10////).

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MEASUREMENT OF THE RATIO OF THE PROTON FORM-FACTORS, G(E) / G(M), AT HIGH MOMENTUM TRANSFERS AND THE QUESTION OF SCALING

Litt, J. ; Buschhorn, G. ; Coward, D.H. ; et al.

Phys.Lett.B 31 (1970) 40-44, 1970.

Inspire Record 54895 DOI 10.17182/hepdata.28767

Electron-proton elastic scattering cross sections have been measured at the Stanford Linear Accelerator Center at four-momentum transfers squared (q 2 ) of 1.0, 1.5, 2.0, 2.5and 3.75 (GeV/ c ) 2 . The angular distributions at q 2 = 2.5 and 3.75 (GeV/ c ) 2 are sufficient to provide values of the ratio G E / G M independent of the results from other laboratories. Our results are compatible with scaling, G E (q 2 ) = G M (q 2 )/ μ , within the experimental errors.

6 data tables match query

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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First Measurements of Hadronic Decays of the $Z$ Boson

The MARK-II collaboration Abrams, G.S. ; Adolphsen, Chris ; Aleksan, R. ; et al.

Phys.Rev.Lett. 63 (1989) 1558, 1989.

Inspire Record 282670 DOI 10.17182/hepdata.20044

We have observed hadronic final states produced in the decays of Z bosons. In order to study the parton structure of these events, we compare the distributions in sphericity, thurst, aplanarity, and number of jets to the predictions of several QCD-based models and to data from lower energies. The data and models agree within the present statistical precision.

5 data tables match query

Table 1

Corrected event shape distributions.

Table 2

Corrected event shape distributions.

Table 3

Corrected event shape distributions.

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A Search for Elastic Nondiagonal Lepton Pair Production in $e^+ e^-$ Annihilation at $\sqrt{s}=29$-{GeV}

Gomez Cadenas, J.J. ; Heusch, C.A. ; Abrams, G.S. ; et al.

Phys.Rev.Lett. 66 (1991) 1007-1010, 1991.

Inspire Record 295203 DOI 10.17182/hepdata.19918

We have searched for the annihilation of e+e− into the exclusive channels e±τ∓ and μ±τ∓ at √s =29 GeV, using 226 and 133 pb−1, respectively, of data taken with the Mark II detector at the SLAC storage ring PEP. The resulting candidate sample is compatible with the expected background from τ pair production. Our analysis yields 95%-C.L. cross-section limits of σeτ/σμμ<1.8×10−3 and σμτ/σμμ<6.1×10−3, where σμμ is the QED cross section for production of a lepton pair. This is the first high-Q2 test of lepton-flavor conservation involving τ leptons.

1 data table match query

Table 1

95 pct confidence upper limits.

Determination of $\alpha^- s$ From a Differential Jet Multiplicity Distribution at {SLC} and {PEP}

Komamiya, Sachio ; Le Diberder, F. ; Abrams, G.S. ; et al.

Phys.Rev.Lett. 64 (1990) 987, 1990.

Inspire Record 283630 DOI 10.17182/hepdata.19937

We measured the differential jet-multiplicity distribution in e+e− annihilation with the Mark II detector. This distribution is compared with the second-order QCD prediction and αs is determined to be 0.123±0.009±0.005 at √s≊MZ (at the SLAC Linear Collider) and 0.149±0.002±0.007 at √s=29 GeV (at the SLAC storage ring PEP). The running of αs between these two center-of-mass energies is consistent with the QCD prediction.

2 data tables match query

Table 1

DIFFERENTIAL JET MULTIPLICITIES.

Table 2

DIFFERENTIAL JET MULTIPLICITIES.

Measurements of Charged Particle Inclusive Distributions in Hadronic Decays of the $Z$ Boson

Abrams, G.S. ; Adolphsen, Chris ; Averill, D. ; et al.

Phys.Rev.Lett. 64 (1990) 1334, 1990.

Inspire Record 283799 DOI 10.17182/hepdata.19999

We have measured inclusive distributions for charged particles in hadronic decays of the Z boson. The variables chosen for study were charged-particle multiplicity, scaled momentum, and momenta transverse to the sphericity axes. The distributions have been corrected for detector effects and are compared with data from e+e− annihilation at lower energies and with the predictions of several QCD-based models. The data are in reasonable agreement with expectations.

4 data tables match query

Table 1

Mean corrected charged particle multiplicity.

Table 2

Corrected charged particle X distributions. Errors are statistical and systematic combined.

Table 3

Corrected charged particle PTIN distributions. Errors are statistical and systematic combined.

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Initial Measurements of Z Boson Resonance Parameters in e+ e- Annihilation

Abrams, G.S. ; Adolphsen, Chris ; Aleksan, R. ; et al.

Phys.Rev.Lett. 63 (1989) 724, 1989.

Inspire Record 280007 DOI 10.17182/hepdata.20034

We have measured the mass of the Z boson to be 91.11±0.23 GeV/c2, and its width to be 1.61−0.43+0.60 GeV. If we constrain the visible width to its standard-model value, we find the partial width to invisible decay modes to be 0.62±0.23 GeV, corresponding to 3.8±1.4 neutrino species.

1 data table match query

Table 1

Data now superceded.

Measurements of Z Boson Resonance Parameters in e+ e- Annihilation

Abrams, G.S. ; Adolphsen, Chris ; Averill, D. ; et al.

Phys.Rev.Lett. 63 (1989) 2173, 1989.

Inspire Record 281818 DOI 10.17182/hepdata.20033

We have measured the mass of the Z boson to be 91.14±0.12 GeV/c2, and its width to be 2.42−0.35+0.45 GeV. If we constrain the visible width to its standard-model value, we find the partial width to invisible decay modes to be 0.46±0.10 GeV, corresponding to 2.8±0.6 neutrino species, with a 95%-confidence-level upper limit of 3.9.

1 data table match query

Table 1

No description provided.

Studies of Jet Production Rates in $e^+ e^-$ Annihilation at $e$({CM}) = 29-{GeV}

Bethke, S. ; Abrams, G. ; Adolphsen, C.E. ; et al.

Z.Phys.C 43 (1989) 325, 1989.

Inspire Record 277772 DOI 10.17182/hepdata.15472

Production rates of multijet hadronic final states are studied ine+e− annihilation at 29 GeV center of mass energy. QCD shower model calculations with exact first order matrix element weighting at the first gluon vertex are capable of reproducing the observed multijet event rates over a large range of jet pair masses. The method used to reconstruct jets is well suited for directly comparing experimental jet rates with parton rates calculated in perturbative QCD. Evidence for the energy dependene of αs is obtained by comparing the observed production rates of 3-jet events with results of similar studies performed at higher center of mass energies.

2 data tables match query

Table 1

Observed production rates relative to the total hadronic cross section.

Table 2

Production rates corrected for fragmentation, initial state radiation and detector effects.

Date

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Determination of the total photon - proton cross-section from high-energy inelastic electron scattering

Photoproduction of $\pi^0$ from Hydrogen near the Second Pion-Nucleon Resonance

MEASUREMENT OF THE RATIO OF THE PROTON FORM-FACTORS, G(E) / G(M), AT HIGH MOMENTUM TRANSFERS AND THE QUESTION OF SCALING

First Measurements of Hadronic Decays of the $Z$ Boson

A Search for Elastic Nondiagonal Lepton Pair Production in $e^+ e^-$ Annihilation at $\sqrt{s}=29$-{GeV}

Determination of $\alpha^- s$ From a Differential Jet Multiplicity Distribution at {SLC} and {PEP}

Measurements of Charged Particle Inclusive Distributions in Hadronic Decays of the $Z$ Boson

Initial Measurements of Z Boson Resonance Parameters in e+ e- Annihilation

Measurements of Z Boson Resonance Parameters in e+ e- Annihilation

Studies of Jet Production Rates in $e^+ e^-$ Annihilation at $e$({CM}) = 29-{GeV}