Date

Polarization Parameters in Neutral Pion Photoproduction

Bussey, P.J. ; Raine, C. ; Rutherglen, J.G. ; et al.
Nucl.Phys.B 154 (1979) 492-502, 1979.
Inspire Record 140230 DOI 10.17182/hepdata.34681

The polarisation parameters Σ, P and T have been measured for the process γ p→ π 0 p in the photon energy range 1300–2100 MeV and c.m. angles between 30° and 110°, in an experiment with a polarised beam and polarised target. The results are compared with a recent theoretical analysis which fits data from threshold to 16 GeV. The new data are in general agreement with the analysis, but with some significant discrepancies in detail.

9 data tables

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Production of $J/\psi$ in 16-{GeV} and 22-{GeV} $\pi^-$ Cu Collisions

LeBritton, J. ; McCal, D. ; Melissinos, A.C. ; et al.
Phys.Lett.B 81 (1979) 401-404, 1979.
Inspire Record 7053 DOI 10.17182/hepdata.50278

We have measured the inclusive production of J ψ in 16 and 22 GeV π − copper collisions in a wide aperture magnetic spectrometer. The cross section per Cu nucleus for x > 0 corrected for branching ratio is 64 ± 38 nb at 16 GeV and 196 ± 38 nb at 22 GeV. As threshold is approached, the mean values of the Feynman x distribution increase and the cross section for J ψ production drops steeply. This can be understood in terms of the quark-fusion model where the antiquark content of the pion makes an increasingly significant contribution as M 2 s increases.

2 data tables

Cross-section Measurements for the Reactions $\nu p \to \mu^- \pi^+ p$ and $\nu p \to \mu^- K^+ p$ at High-Energies

Bell, J. ; Coffin, C.T. ; Diamond, R.N. ; et al.
Phys.Rev.Lett. 41 (1978) 1008, 1978.
Inspire Record 131344 DOI 10.17182/hepdata.24326

We present results for the reactions νp→μ−π+p and νp→μ−K+p at energies above 5 GeV. The average cross section for the first reaction between 15 and 40 GeV is (0.80±0.12) × 10−38 cm2 and for events with Mπ+p<1.4 GeV is (0.55±0.08) × 10−38 cm2. The ratio of the cross section for the second reaction to that for the first is 0.017±0.010.

4 data tables

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RAPIDITY IS MEASURED IN 'QUARK' REST FRAME DEFINED AS Y(Q)=Y(LAB)-LOG(W**2/M**2) WHERE Y(LAB)=0.5*LOG((E+PL)/(E-PL)).

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Forward and Wide Angle Elastic $\phi$ - Meson Photoproduction on Hydrogen Between 2.8-{GeV} and 4.8-{GeV}

The LAMP2 Group collaboration Barber, D.P. ; Dainton, J.B. ; Lee, L.C.Y. ; et al.
Phys.Lett.B 79 (1978) 150-156, 1978.
Inspire Record 131968 DOI 10.17182/hepdata.27382

The s and t dependence of φ (1019) photoproduction has been investigated in the incident photon energy range 2.8 to to 4.8 GeV. Differential cross-sections and density matrix elements are presented for a t range extending from t min out to −1.3 (GeV/ c ) 2 . The results are discussed in terms discussed in terms of an effective Regge trajectory in the t -channel.

5 data tables

DIFFERENTIAL CROSS SECTIONS AVERAGED OVER TWO RANGES OF INCIDENT PHOTON ENERGY.

VARIATION OF SMALL -T DIFFERENTIAL CROSS SECTION WITH PHOTON ENERGY.

INTERCEPT AND SLOPE FROM FITS TO D(SIG)/DT AT SMALL -T.

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INCLUSIVE pi0 PHOTOPRODUCTION AND THE QUARK - PARTON MODEL

The LAMP2 Group collaboration Barber, D.P. ; Dainton, J.B. ; Lee, L.C.Y. ; et al.
Phys.Lett.B 77 (1978) 233-239, 1978.
Inspire Record 129937 DOI 10.17182/hepdata.27429

We present measurements on the inclusive structure function for π 0 photoproduction for the incident photon energy range of 2.8–4.8 GeV. Comparisons are made with electroproduction data and it is found that the scaling behaviour already observed for finite q 2 continues to be valid at q 2 = 0.

1 data table

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Backward Resonance Production in pi- p --> n pi+ pi- at 8-GeV/c

Eisenstein, Bob I. ; Elliott, J. ; Mollet, W. ; et al.
Phys.Rev.D 18 (1978) 1370-1381, 1978.
Inspire Record 136306 DOI 10.17182/hepdata.24374

We have studied backward meson and baryon production in π−p→nπ+π− at 8 GeV/c using a streamer chamber triggered by the detection of the interaction of the neutron in thick-plate optical spark chambers. Our data sample of 866 events is dominated by the quasi-two-body final states Δ−(1232)π+, nρ0, and nf0. We study the differential and total backward cross sections for these states and the decay angular distributions of the resonances. The results for the Δ− and ρ0 indicate that both nucleon and Δ exchange in the u channel are important in their production, while f0 production is, as expected, consistent with nucleon exchange.

5 data tables

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BACKWARD DIP.

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Evidence for a Resonant Structure of the Hadron Production from e+ e- Annihilations in the 1700-MeV-1950-MeV Center-Of-Mass Energy Region

Ambrosio, M. ; Barbarino, G. ; Barbiellini, G. ; et al.
Phys.Lett.B 68 (1977) 397-401, 1977.
Inspire Record 119882 DOI 10.17182/hepdata.27553

We present experimental evidence for a resonant behaviour of the hadron production from e + e − annihilations at the e + e − storage ring ADONE. A Breit-Wigner fit to the enhancement present between 1800 and 1850 MeV gives the following parameters M = 1812 −13 +7 MeV, Γ = 34 −15 +21 MeV.

1 data table

MULTIHADRON EVENTS (AT LEAST THREE CHARGED TRACKS) PER UNIT LUMINOSITY.


The Polarized Target Asymmetry for Neutral Pion Photoproduction from Protons in the Photon Energy Range 0.7-GeV-1.45-GeV

Booth, P.S.L. ; Carroll, L.J. ; Court, G.R. ; et al.
Nucl.Phys.B 121 (1977) 45-57, 1977.
Inspire Record 111591 DOI 10.17182/hepdata.35454

Measurements have been made of the target asymmetry parameter for photoproduction of π 0 mesons from protons, using a butanol polarised target with a 3 He cryostat. Results were obtained at 14 incident photon energies between 0.7 GeV and 1.45 GeV over an angular range ∼40° to 145° c.m. The recent analysis of Barbour and Crawford provides a very good fit to the data.

14 data tables

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Backward Photoproduction of rho0 and f Between 2.8-GeV and 4.8-GeV

Clifft, R.W. ; Dainton, J.B. ; Gabathuler, E. ; et al.
Phys.Lett.B 64 (1976) 213-216, 1976.
Inspire Record 109693 DOI 10.17182/hepdata.27627

A measurement of backward photoproduction of charged pion pairs on protons is reported. The pion pair mass spectrum shows strong ϱ ° and f production. Data are presented on the u and s dependence for ϱ O and f, together with the decay polarisation for the ϱ O .

3 data tables

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AVERAGED OVER U RANGE OF EXPERIMENT. NO EVIDENCE FOR ANY LARGE S-WAVE CONTRIBUTION TO THE PI PI SYSTEM IN THE RHO0 MASS REGION (RHO(0S) < -0.03 +- 0.13). U CHANNEL FRAME: Z AXIS IN INCIDENT PROTON DIRECTION IN THE DIPION REST FRAME.


Search for Parity Nonconservation in Atomic Bismuth

Soreide, D.C. ; Roberts, D.E. ; Lindahl, E.G. ; et al.
Phys.Rev.Lett. 36 (1976) 352-355, 1976.
Inspire Record 112866 DOI 10.17182/hepdata.21089

In a search for optical rotation near the 8755-Å magnetic-dipole absorption line in atomic Bi, our first results set an upper limit F<10−6 on a parity nonconserving amplitude associated with the line. This limit improves upon earlier parity tests in atoms by three orders of magnitude. Further improvement of at least another order of magnitude appears possible by this method which should then provide an exacting test of parity conservation in the neutral weak-current interaction in atoms.

1 data table

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