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Measurement of the proton antiproton pair production from two-photon collisions at TRISTAN.

The VENUS collaboration Hamasaki, H. ; Abe, K. ; Amako, K. ; et al.
Phys.Lett.B 407 (1997) 185-192, 1997.
Inspire Record 443677 DOI 10.17182/hepdata.38332

The cross section of the γγ → p p reaction was measured at two-photon center-of-mass energy ( W γγ ) between 2.2 and 3.3 GeV, using the two-photon process at an e + e − collider, TRISTAN. The W γγ dependence of the cross section integrated over a c.m. angular region of | cos θ ∗ | < 0.6 is in good agreement with the previous measurements and the theoreticalv prediction based on diquark model in the high W γγ region.

2 data tables
Table 1

Numerical values supplied by Hirhoshi Hamasaki.

Table 2

Angular distributions.


D*+- inclusive production in two-photon process at s**(1/2) = 58-GeV in TRISTAN.

The VENUS collaboration Ohyama, H. ; Abe, K. ; Amako, K. ; et al.
Z.Phys.C 75 (1997) 209-214, 1997.
Inspire Record 428204 DOI 10.17182/hepdata.38337

Using the VENUS detector at TRISTAN we have investigated the charm-quark production by detecting D*+ - mesons in the two-photon process of e+et - collisions. The study has confirmed that the charm-quark production rate is larger than that predicted from direct cc̅ production alone. The distribution of the transverse momentum of the D*+ t- mesons and the forward energy flow associated with the D*+ - production suggest that the main part of the observed excess comes from the contribution of a resolved photon process.

1 data table
Table 1

D* production cross section in the given kinematic ranges under the anti-tagging condition |cos(theta(e+-))|>0.990.


Precise measurement of Bhabha scattering at a center-of-mass energy of 57.77-GeV.

The VENUS collaboration Arima, T. ; Odaka, S. ; Ogawa, K. ; et al.
Phys.Rev.D 55 (1997) 19-39, 1997.
Inspire Record 421762 DOI 10.17182/hepdata.38325

Bhabha scattering at a center-of-mass energy of 57.77 GeV has been measured using the VENUS detector at KEK TRISTAN. The precision is better than 1% in scattering angle regions of |cosθ|⩽0.743 and 0.822⩽cosθ⩽0.968. A model-independent scattering-angle distribution is extracted from the measurement. The distribution is in good agreement with the prediction of the standard electroweak theory. The sensitivity to underlying theories is examined, after unfolding the photon-radiation effect. The q2 dependence of the photon vacuum polarization, frequently interpreted as a running of the QED fine-structure constant, is directly observed with a significance of three standard deviations. The Z0 exchange effect is clearly seen when the distribution is compared with the prediction from QED (photon exchanges only). The agreement with the standard theory leads us to constraints on extensions of the standard theory. In all quantitative discussions, correlations in the systematic error between angular bins are taken into account by employing an error matrix technique.

1 data table
Table 1

Cross section is integrated over the cos(theta ) bin.


Study of inclusive baryon - anti-baryon pair production of P or Lambda in two photon processes

The VENUS collaboration Uehara, S. ; Abe, K. ; Amako, K. ; et al.
Z.Phys.C 69 (1996) 597-606, 1996.
Inspire Record 400152 DOI 10.17182/hepdata.38341

Inclusive baryon-antibaryon pair production was studied in two-photon events which were collected at the e+e− collider TRISTAN, and correspond to an integrated luminosity of 303 pbt?1. Correlations between a baryon and an antibaryon were studied for their flavors (p or Λ) and their momentum vectors. The experimental results were compared with the expectations from a jet-fragmentation Monte Carlo simulation. We have found that although the ratios of the cross sections of different baryon-flavor combinations are consistent with the Monte Carlo expectations, the cross section shows an excess over the Monte Carlo expectation in a low invariant-mass region of final-state particles at large angles, that indicates a significant contribution from higher-order QCD or non-perturbative effects. The experimental data show no narrow azimuthal-angle correlation, which is expected from a jet-fragmentation Monte Carlo. A search for exclusive Λ pair production has also been made. We have no candidates and have obtained the upper limit for the cross section.

4 data tables
Table 1

Topological cross section for events in anti-tagged two photon processes.

Table 2

Ratios of cross sections. Here 'p' includes the protons from the decay of any hadrons, except for lambdas. 'lambda' includes all decay products.

Table 3

Upper limits (95% CL) assuming shape of the W dependence is W**(-12)(BETA*(LAMBDA)) where BETA*(LAMBDA) is the velocity of the LAMBDA in the c.m. frame of the gamma-gamma.

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Study of Multi - Hadron Events With Isolated Leptons in $e^+ e^-$ Annihilation at $50\le \sqrt{s} \le 55$-{GeV}

The VENUS collaboration Abe, K. ; Amako, K. ; Arai, Y. ; et al.
Phys.Lett.B 207 (1988) 355-360, 1988.
Inspire Record 23570 DOI 10.17182/hepdata.29946

We have studied inclusive lepton production in e + e − annihilations into multihadrons in the energy range between √ s =50 and 55 GeV using the VENUS detector at TRISTAN, KEK. Though MARK-J and JADE groups at PETRA found an excess of isolated muon events at √ s ⩾46.3 GeV, we have not observed such an anomaly in muon nor in electron production. The observed rates of isolated leptons are consistent with the production and decay of five known quarks.

4 data tables
Table 1

Observed rates for whole event sample.

Table 2

No description provided.

Table 3

No description provided.

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Measurement of the Reactions $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \gamma \gamma$ at $\sqrt{s}=52$-{GeV}

The VENUS collaboration Abe, Koya ; Amako, Katsuya ; Arai, Yasuo ; et al.
J.Phys.Soc.Jap. 56 (1987) 3767-3770, 1987.
Inspire Record 251276 DOI 10.17182/hepdata.38511

None

2 data tables
Table 1

No description provided.

Table 2

No description provided.