HEPData Search

A search for the reactionsγγ→ωω andγγ→ρ0ω has been carried out at an averagee+e− CM energy of 34.6 GeV with an integrated luminosity of 45 pb−1. Upper limits are set for these two channels over the γγ CM Energy range of 1.6 to 2.5 GeV. The cross section is determined for the exclusive channelγγ→π+2π−π0.

3 data tables

Table 1

Data read from graph.

Table 2

Data read from graph.

Table 3

Data read from graph.

Tensor Meson Excitation in the Reaction $\gamma \gamma \to K^0_S K^0_S$

The PLUTO collaboration Berger, Christoph ; Genzel, H. ; Lackas, W. ; et al.

Z.Phys.C 37 (1988) 329, 1988.

Inspire Record 250982 DOI 10.17182/hepdata.15690

In the analysis of the reactione+e−→e+e−KS0Ks0 clear evidence for exclusive γγ→f2′ resonance production is observed. The productΓγγ ·B(f2′→K$\bar K$) is measured to be 0.10−0.03−0.02+0.04+0.03 keV independent of ana priori assumption on the helicity structure. Our data are consistent with a pure helicity 2 contribution and we derive an upper limit for the ratioΓγγ(0)/Γγγ. The absence of events in the mass region around 1.3 GeV clearly proves destructivef2−a2 interference and allows to measure the relative phases betweenf2,a2 andf2′. Upper limits on the production of the glueball candidate statesf2(1720) andX(2230) as well as theKS0KS0-continuum are given.

1 data table

Table 1

Data read from graph.

Measurement and Analysis of the Reaction $\gamma \gamma \to \pi^+ \pi^- \pi^+ \pi^-$

The PLUTO collaboration Berger, Christoph ; Genzel, H. ; Lackas, W. ; et al.

Z.Phys.C 38 (1988) 521, 1988.

Inspire Record 252632 DOI 10.17182/hepdata.1916

We have measured the cross section of four charged pion production in photon-photon interactions in the invariant mass range 1.0≦Wγγ≦3.2 GeV and up toQ2=16 GeV2. For 1.2 GeV≦Wγγ≦1.7 GeV the process is dominated by ρ0ρ0 production with a rapid rise in cross section around 1.2 GeV, well below the nominal ρ0ρ0 threshold. The observed distributions in the two particle masses and in the production and decay angles are well described by an incoherent sum of the phase-space subprocesses γγ →ρ0ρ0, →ρ0π+π−, and →π+π−π+π−. A spin-parity analysis of the ρ0ρ0 system showsJP=2+ to dominate, although 0+ is also possible forWγγ≦1.4 GeV. Negative partity states are excluded.

12 data tables

Table 1

Fractions of subprocesses from 3-parameter fit to the no-tag data.

Table 2

Fractions of subprocesses from 2-parameter fit to the no-tag data in limited energy range. The Q=1R contribution is set equal to zero.

Table 3

Fractions of subprocesses from 3-parameter fit to the single-tag data.

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W2 and Q2 dependence of charged hadron and pion multiplicities in neutrino p and anti-neutrino p charged current interactions

The WA21 collaboration Jones, G.T. ; Jones, R.W.L. ; Morrison, Douglas R.O. ; et al.

Z.Phys.C 46 (1990) 25-34, 1990.

Inspire Record 305244 DOI 10.17182/hepdata.1699

Using data onvp and$\bar vp$ charged current interactions from a bubble chamber experiment with BEBC at CERN, the average multiplicities of charged hadrons and pions are determined as functions ofW2 andQ2. The analysis is based on ∼20000 events with incidentv and ∼10000 events with incident$\bar v$. In addition to the known dependence of the average multiplicity onW2 a weak dependence onQ2 for fixed intervals ofW is observed. ForW>2 GeV andQ2>0.1 GeV2 the average multiplicity of charged hadrons is well described by〈n〉=a1+a2ln(W2/GeV2)+a3ln(Q2/GeV2) witha1=0.465±0.053,a2=1.211±0.021,a3=0.103±0.014 for thevp anda1=−0.372±0.073,a2=1.245±0.028,a3=0.093±0.015 for the$\bar vp$ reaction.

72 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Measurement of the isolated prompt photon cross-sections in anti-p p collisions at s**(1/2) = 1.8-TeV

The CDF collaboration Abe, F. ; Amidei, Dante E. ; Apollinari, G. ; et al.

Phys.Rev.Lett. 68 (1992) 2734-2738, 1992.

Inspire Record 333081 DOI 10.17182/hepdata.19869

We present a measurement of the cross section for production of isolated prompt photons in p¯p collisions at √s =1.8 TeV. The cross section, measured as a function of transverse momentum (PT), agrees qualitatively with QCD calculations but has a steeper slope at low PT.

1 data table

Table 1

Additional normalization systematic uncertainty of 27 pct for first eleven entries, and +32 pct(-46 pct) for last four entries.

First measurement of the polarization transfer on the proton in the reactions H (e (polarized), e-prime p (polarized)) and D (e (polarized), e-prime p (polarized))

Eyl, D. ; Frey, A. ; Andresen, H.G. ; et al.

Z.Phys.A 352 (1995) 211-214, 1995.

Inspire Record 406592 DOI 10.17182/hepdata.16499

The measurement of the polarisation transfer to the proton in the reactions$H(\vec e,e'\vec p)$ and$D(\vec e,e'\vec p)$ performed with longitudinally polarised electrons in quasi-free kinematics is presented. The coincidence measurement was executed atQ2≈8fm−2 using the 855 MeV, c.w. beam of the Mainz Microtron MAMI. The recoil polarisation was determined by means of a carbon analyser. The experiment shows that the binding of the nucleon does not modify the polarisationPx of the recoil proton within an error ofΔPx/Px≈10%. The measured polarisation agrees with recent theoretical predictions. Implications for the measurement of the electric form factor of the neutron using the$D(\vec e,e'\vec n)$ reaction are discussed.

1 data table

Table 1

No description provided.

Neutral pion photoproduction from the proton near threshold

Fuchs, M ; Ahrens, J ; Anton, G ; et al.

Phys.Lett.B 368 (1996) 20-25, 1996.

Inspire Record 428389 DOI 10.17182/hepdata.28430

Differential and total cross sections for the photoproduction of neutral pions from the proton have been measured for incident photon energies from 140–270 MeV, using the photon spectrometer TAPS at the tagged photon beam of the 855 MeV Mainz Microtron. The energy dependence of the s- and p-wave multipoles close to threshold was deduced from a multipole fit and a multipole analysis. The extracted s-wave amplitude E 0+ at threshold is found to be significantly smaller than the prediction of the classical low energy theorems, but is in reasonable agreement with the chiral perturbation theory.

1 data table

Table 1

No description provided.

Near threshold photoproduction of eta mesons from He-4.

Hejny, V. ; Achenbach, P. ; Ahrens, J. ; et al.

Eur.Phys.J.A 6 (1999) 83-89, 1999.

Inspire Record 509583 DOI 10.17182/hepdata.43494

None

1 data table

Table 1

SIG(Q=N) and SIG(Q=P) ratio is extracted from the data of scattering on HE4.

Date

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Reactions

Observables

CM Energies (GeV) Reset

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MEASUREMENT OF POLARIZATION OF RECOIL PROTONS IN PI0 PHOTOPRODUCTION FOR THETA* (PI0) = 60-degrees IN RESONANCE REGION. (IN RUSSIAN)

MEASUREMENT OF ASYMMETRY IN CROSS-SECTION OF GAMMA P ---> P PI0 REACTION IN THE RESONANCE REGION. (IN RUSSIAN)

Study of the Reaction $\gamma \gamma \to 2 \pi^+ 2 \pi^- \pi^0$ and Upper Limits on the Production of $\gamma \gamma \to \omega \omega$ and $\gamma \gamma \to \rho^0 \omega$

Tensor Meson Excitation in the Reaction $\gamma \gamma \to K^0_S K^0_S$

Measurement and Analysis of the Reaction $\gamma \gamma \to \pi^+ \pi^- \pi^+ \pi^-$

W2 and Q2 dependence of charged hadron and pion multiplicities in neutrino p and anti-neutrino p charged current interactions

Measurement of the isolated prompt photon cross-sections in anti-p p collisions at s**(1/2) = 1.8-TeV

First measurement of the polarization transfer on the proton in the reactions H (e (polarized), e-prime p (polarized)) and D (e (polarized), e-prime p (polarized))

Neutral pion photoproduction from the proton near threshold

Near threshold photoproduction of eta mesons from He-4.