Gather, K.
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Rho rho Production by Two Photon Scattering

The TASSO collaboration Brandelik, R. ; Braunschweig, W. ; Gather, K. ; et al.
Phys.Lett.B 97 (1980) 448, 1980.
Inspire Record 154418 DOI 10.17182/hepdata.27137
1 data table
Table 1

Additional systematic uncertainty 25% not included.


INELASTIC ELECTRON PHOTON SCATTERING AT MODERATE FOUR MOMENTUM TRANSFERS

The PLUTO collaboration Berger, Christoph ; Genzel, H. ; Grigull, R. ; et al.
Phys.Lett.B 99 (1981) 287-291, 1981.
Inspire Record 155594 DOI 10.17182/hepdata.27125

We present new high statistics data on hadron production in photon-photon reactions. The data are analyzed in terms of an electron-photon scattering formalism. The dependence of the total cross section of Q 2 , the four-momentum transfer squared of the scattered electron, and on the mass W of the hadronic system is investigated. The data are compared to predictions from Vector-Meson Dominance and the quark model.

3 data tables
Table 1

No description provided.

Table 2

DEPENDENCE ON VISIBLE HADRONIC INVARIANT MASS.

Table 3

Data read from graph.


High $p_T$ Hadron Production in Photon - Photon Collisions

The TASSO collaboration Brandelik, R. ; Braunschweig, W. ; Gather, K. ; et al.
Phys.Lett.B 107 (1981) 290-296, 1981.
Inspire Record 167417 DOI 10.17182/hepdata.31027

We have studied the properties of hadron production in photon-photon scattering with tagged photons at the e + e − storage ring PETRA. A tail in the p T distribution of particles consistent with p T −4 has been observed. We show that this tail cannot be due to the hadronic part of the photon. Selected events with high p T particles are found to be consistent with a two-jet structure as expected from a point-like coupling of the photons to quarks. The lowest-order cross section predicted for γγ → q q , σ = 3 Σ e q 4 · σ γγ → μμ , is approached from above by the data at large transverse momenta.

1 data table
Table 1

No description provided.


First Measurement of the Photon Structure Function F2

The PLUTO collaboration Berger, Christoph ; Genzel, H. ; Grigull, R. ; et al.
Phys.Lett.B 107 (1981) 168-172, 1981.
Inspire Record 167681 DOI 10.17182/hepdata.31043

Using data taken at PETRA we present results on deep inelastic electron photon scattering at momentum transfers 1 < Q 2 < 15 GeV 2 . The results are expressed in terms of the photon structure function F 2 and are compared with QCD predictions and “hadronic” models of the photon. The pointlike component of the photon is found to be dominant.

2 data tables
Table 1

Data read from graph.. Data for W < 3.5 in Berger et al. 1981, PL 99B,287 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1164> RED = 1164 </a>).

Table 2

PHOTON STRUCTURE FUNCTION. NUMERICAL VALUES OF DATA ON FIGURE SUPPLIED BY W. WAGNER.


Exclusive Proton - Anti-proton Production in Two Photon Collisions

The TASSO collaboration Brandelik, R. ; Braunschweig, W. ; Gather, K. ; et al.
Phys.Lett.B 108 (1982) 67-70, 1982.
Inspire Record 167679 DOI 10.17182/hepdata.31000

Production of proton-antiproton pairs by two-photon scattering has been observed at the electron-position storage ring PETRA. A total of eight proton-antiproton pairs have been identified using the time-of-flight technique. We have measured a total cross section of 4.5 ± 0.8 nb in the photon-photon c.m. energy range 2.0–2.6 GeV.

1 data table
Table 1

No description provided.


Experimental Study of the Photon Structure Function F(2) in the High $Q^2$ Region

The JADE collaboration Bartel, W. ; Cords, D. ; Dietrich, G. ; et al.
Phys.Lett.B 121 (1983) 203-208, 1983.
Inspire Record 180758 DOI 10.17182/hepdata.30781

We report on a measurement of the process e + e − →e + e − + hadrons, where one of the scattered electrons is detected at large angles, with an average Q 2 of 23 GeV. The results are analysed in terms of the photon structure function F 2 and are compared with QCD predictions.

3 data tables
Table 1

Data read off graph.

Table 2

Data read off graph.

Table 3

Data read off graph.


Production of $K \bar{K}$ Pairs in Photon-photon Collisions and the Excitation of the Tensor Meson F-prime (1515)

The TASSO collaboration Althoff, M. ; Brandelik, R. ; Braunschweig, W. ; et al.
Phys.Lett.B 121 (1983) 216-222, 1983.
Inspire Record 181468 DOI 10.17182/hepdata.30814

We have observed exclusive production of K + K − and K S O K S O pairs and the excitation of the f′(1515) tensor meson in photon-photon collisions. Assuming the f′ to be production in a helicity 2 state, we determine Λ( f ′ → γγ) B( f ′ → K K ) = 0.11 ± 0.02 ± 0.04 keV . The non-strange quark of the f′ is found to be less than 3% (95% CL). For the θ(1640) we derive an upper limit for the product Λ(θ rarr; γγ K K ) < 0.03 keV (95% CL ) .

2 data tables
Table 1

Data read from graph.. Errors are the square roots of the number of events.

Table 2

Data read from graph.. Errors are the square roots of the number of events.


Experimental Study of the Hadronic Photon Structure Function

The CELLO collaboration Behrend, H.J. ; Fenner, H. ; Gumpel, U. ; et al.
Phys.Lett.B 126 (1983) 391-397, 1983.
Inspire Record 198110 DOI 10.17182/hepdata.30720

We have measured at PETRA the process e γ → e + hadrons at an average Q 2 value of 9 GeV 2 / c 2 . The total number of observed events attributed to this process is 215. Our data are compared to calculations based on the estimation of the photon structure function F 2 in the quark parton model and in QCD.

1 data table
Table 1

No description provided.


Measurement of the Reaction gamma gamma ---> pi+ pi+ pi- pi- at PETRA

The CELLO collaboration Behrend, H.J. ; Fenner, H. ; Schachter, M.J. ; et al.
Z.Phys.C 21 (1984) 205, 1984.
Inspire Record 191578 DOI 10.17182/hepdata.16344

We have determined the cross section for γγ→π+π+π−π− in a way free of assumptions about the relative contributions fromρ0ρ0,ρ02π and 4π (uncorrelated phase space). We find a sharp onset above threshold and a rather high cross section of about 200 nb aroundWγγ=1.5 GeV which consists to about 40% ofρ0ρ0 production with sizeable contributions fromρ02π and 4π (PS). The total cross section as well as theρ0ρ0 content fall rather fast at higher c.m. energies. Attempts to explain this behaviour in terms of production of known resonances are not successful so far. The angular distributions do not show any significant structure pointing to resonance formation in the 4π-system. Only theρ0-meson is observed in the moment analysis. The decay distributions of theρ0 for forward produced rhos are fairly consistent with helicity conservation of the produced rhos in accordance with the VDM picture.

5 data tables
Table 1

No description provided.

Table 2

RESULTS OF DECOMPOSITION OF THE CROSS SECTION INTO RHO RHO, RHO 2PI, AND 4PI(PHASE SPACE) USING TWO WIDE W BINS. SEE TEXT OF PAPER FOR DISCUSSION OF FITS.

Table 3

RESULTS OF DECOMPOSITION OF THE CROSS SECTION INTO THE RHO RHO, RHO PI, AND 4PI (PHASE SPACE) USING SMALL W BINS. SEE TEXT OF PAPER FOR DISCUSSION OF FITS.

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Observation of the Production of $\eta$ Mesons in Two Photon Collisions

Weinstein, A. ; Antreasyan, D. ; Gu, Y.F. ; et al.
Phys.Rev.D 28 (1983) 2896, 1983.
Inspire Record 192651 DOI 10.17182/hepdata.23791

Using 2674 nb−1 of data taken at s from 5.00 to 7.25 GeV with a trigger sensitive to decays of lower-mass particles produced in two-photon collisions, we have observed 56±12 events consistent with the reaction e+e−→e+e−η, η→γγ. Background has been subtracted using separated-beam data. We obtain Γγγ(η)=0.56±0.16 keV and the pseudoscalar-nonet mixing angle θP=−17.6°±3.6°.

1 data table
Table 1

No description provided.