HEPData Search

The e + e − → p p cross section has been measured in the energy interval (1975 ⩽ 2 E ⩽ 2250) MeV for |cos θ | < 0.7. The measurement is based on ∼ 100 events, thus improving by a factor 3 on the previous existing statistics in this energy interval. The form factor | G | 2 is given as a function of energy under the assumption | G E | = | G M |. We also give the first measurement of the differential cross section, averaged over the energy interval, and estimate the ratio G M |/| G E | from it.

3 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

A Measurement of $\pi^0 \pi^0$ Production in Two Photon Collisions

The Crystal Ball collaboration Marsiske, H. ; Antreasyan, D. ; Bartels, H.W. ; et al.

Phys.Rev.D 41 (1990) 3324, 1990.

Inspire Record 294492 DOI 10.17182/hepdata.22923

The reaction e+e−→e+e−π0π0 has been analyzed using 97 pb−1 of data taken with the Crystal Ball detector at the DESY e−e+ storage ring DORIS II at beam energies around 5.3 GeV. For the first time we have measured the cross section for γγ→π0π0 for π0π0 mvariant masses ranging from threshold to about 2 GeV. We measure an approximately flat cross section of about 10 nb for W=mπ0π0<0.8 GeV, which is below 0.6 GeV, in good agreement with a theoretical prediction based on an unitarized Born-term model. At higher invariant masses we observe formation of the f2(1270) resonance and a hint of the f0(975). We deduce the following two-photon widths: Γγγ(f2(1270))=3.19±0.16±0.280.29 keV and Γγγ(f0(975))<0.53 keV at 90% C.L. The decay-angular distributions show the π0π0 system to be dominantly spin 0 for W<0.7 GeV and spin 2, helicity 2 in the f2(1270) region, with helicity 0 contributing at most 22% (90% C.L.).

2 data tables

Table 1

Statistical errors only.

Table 2

Statistical errors only.

A Measurement of the Electroweak Induced Charge Asymmetry in e+ e- ---> B anti-B

The JADE collaboration Bartel, W. ; Becker, L. ; Bowdery, C. ; et al.

Phys.Lett.B 146 (1984) 437-442, 1984.

Inspire Record 203144 DOI 10.17182/hepdata.6565

The forward-backward charge asymmetry for the process e + e − → b b ̄ → μ ± + hadrons has been measured using the JADE detector at PETRA. An asymmetry of (−22.8 ± 6.0 ± 2.5)% was observed at an average center of mass energy of 34.6 GeV. For comparison, an asymmetry of −25.2% is expected on the basis of the standard Glashow-Salam-Weinberg model.

4 data tables

Table 1

THE VALUE OF CONST HAVE BEEN RESCALED TO DEFINITION I3(Q) = 1/2 BY OPY.

Table 2

No description provided.

Table 3

No description provided.

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A STUDY OF DELTA++ AND DELTA0 ISOBAR INCLUSIVE PRODUCTION IN K- p INTERACTIONS AT 32-GeV/c

Babintsev, V.V. ; Bogolyubsky, M.Yu. ; Bumazhnov, V.A. ; et al.

Sov.J.Nucl.Phys. 39 (1984) 414, 1984.

Inspire Record 190556 DOI 10.17182/hepdata.41019

22 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

EVENTS WITH IDENTIFIED PROTONS.

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A STUDY OF e+ e- ANNIHILATION IN THE 1400-MeV TO 2250-MeV ENERGY RANGE WITH THE MAGNETIC DETECTOR DM2 AT DCI

Augustin, J.E. ; Ayach, L. ; Calcaterra, A. ; et al.

LAL-83-21, 1983.

Inspire Record 192321 DOI 10.17182/hepdata.13242

None

5 data tables

Table 1

ASSUMING ABS(GE)=ABS(GM).

Table 2

No description provided.

Table 3

No description provided.

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rivet Analysis
A Summary of Recent Experimental Results From Mark-$J$: High-energy $e^+ e^-$ Collisions at {PETRA}

The Mark-J collaboration Adeva, B. ; Barber, D.P. ; Becker, U. ; et al.

Phys.Rept. 109 (1984) 131, 1984.

Inspire Record 196567 DOI 10.17182/hepdata.30997

None

6 data tables

Table 1

DATA ARE CORRECTED FOR TWO-PHOTON AND TAU PRODUCTION EFFECTS, ACCEPTANCE AND QED RADIATIVE EFFECTS UP TO ORDER ALPHA**3. THERE IS ALSO A 6 PCT NORMALISATION ERROR NOT INCLUDED. THE OVERALL AVERAGE VALUE OF R FROM THIS DATA IS 3.88 +- 0.04 +- 0.22.

Table 2

No description provided.

Table 3

SEE PRL 55, 665 FOR MOST RECENT VALUES OF THE MU+ MU- CROSS SECTIONS.

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A Test of Universality of Charged Leptons

Barber, D.P. ; Becker, U. ; Benda, H. ; et al.

Phys.Rev.Lett. 43 (1979) 1915, 1979.

Inspire Record 142012 DOI 10.17182/hepdata.20759

Measurements of the reactions e++e−→e++e−, μ++μ−, and τ++τ− at PETRA energies (s12=13,17,27.4,30 and 31.6 GeV) are reported. The results show that these reactions agree well with the predictions of quantum electrodynamics thus determining that all the known charged leptons are pointlike particles to a distance < × 10−16 cm.

2 data tables

Table 1

No description provided.

Table 2

No description provided.

A study of gamma gamma -> Ks Ks production at energies of 2.4-4.0GeV at Belle

The Belle collaboration Chen, W.T. ; Abe, Kazuo ; Abe, K. ; et al.

Phys.Lett.B 651 (2007) 15-21, 2007.

Inspire Record 726900 DOI 10.17182/hepdata.38419

$K^0_SK^0_S$ production in two-photon collisions has been studied using a 397.6 fb$^{-1}$ data sample collected with the Belle detector at the KEKB $e^+e^-$ collider. For the first time the cross sections are measured in the two-photon center-of-mass energy range between 2.4 GeV and 4.0 GeV and angular range $|\cos\theta^*|<0.6$. Combining the results with measurements of $\gamma\gamma\to K^+K^-$ from Belle, we observe that the cross section ratio $\sigma(K^0_SK^0_S)/\sigma(K^+K^-)$ decreases from ~0.13 to ~0.01 with increasing energy. Signals for the $\chi_{c0}$ and $\chi_{c2}$ charmonium states are also observed.

7 data tables

Table 1

Total cross section for the process GAMMA GAMMA --> K0S K0S.

Table 2

Angular distribution of the cross section in the W range 2.4 to 2.5 GeV.

Table 3

Angular distribution of the cross section in the W range 2.5 to 2.6 GeV.