Ansari, S.
E+ E- Scattering
Max results
Sort by Reverse order

Showing 10 of 965 results

Date

rivet Analysis
Study of Hadron and Inclusive Muon Production From Electron Positron Annihilation at 39.79-{GeV} $\le \sqrt{s} \le$ 46.78-{GeV}

The Mark-J collaboration Adeva, B. ; Ansari, S. ; Becker, U. ; et al.
Phys.Rev.D 34 (1986) 681-691, 1986.
Inspire Record 230297 DOI 10.17182/hepdata.23423

We use the reaction e+e−→hadrons, in the Mark J detector at the DESY electron-positron collider PETRA, to determine the hadronic cross section up to 46.78 GeV. The production of a top quark with a charge equal to (2/3) is excluded up to 46.6 GeV with 95% C.L. The observed rise in the cross section at higher energies is consistent with the electroweak prediction for a Z0 mass of 93 GeV. We describe some unusual muon inclusive events.

3 data tables
Table 1

Errors are statistical only.

Table 2

Energy scan of R.

Table 3

Inclusive muon cross section.


Direct Measurements of Charmed d Meson Hadronic Branching Fractions

The MARK-III collaboration Baltrusaitis, R.M. ; Becker, J. ; Blaylock, G. ; et al.
Phys.Rev.Lett. 56 (1986) 2140, 1986.
Inspire Record 220653 DOI 10.17182/hepdata.20248

A new technique is applied to data collected at the ψ(3770) resonance to derive charmed-D-meson branching fractions without relying on the measurement of D-production cross sections. Measurements are presented for three decay modes of the D0 (K−π+, D−π−π+π+, and K−π+π0 and four decay modes of the D+ (K−π+π+,K−π+π+π0,KS0π+, and KS0π+π0). The resulting branching fractions are significantly larger than previous measurements.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


rivet Analysis
A Measurement of the Direct Photon Spectrum From the $\Upsilon$ (1s)

The CLEO collaboration Csorna, S.E. ; Mestayer, M.D. ; Panvini, R.S. ; et al.
Phys.Rev.Lett. 56 (1986) 1222, 1986.
Inspire Record 220652 DOI 10.17182/hepdata.20260

We have observed decays of the ϒ(1S) into hadronic final states containing high-energy photons. These are interpreted as coming from the decay ϒ(1S)→γ+gluon+gluon. We compare the shape of the observed photon energy spectrum with several theoretical predictions and deduce the value of the strong-coupling constant αs and the QCD scale parameter ΛMS― (MS― denotes the modified minimal-subtraction scheme) associated with each prediction.

2 data tables
Table 1

DATA TAKEN ON THE PEAK OF THE UPSI(9460).

Table 2

DATA TAKEN ON THE PEAK OF THE UPSI(9460).


Precision Test of {QED} by Direct Comparison of $e^+ e^- \to \gamma \gamma$ and $e^+ e^- \to e^+ e^-$ at 29-{GeV}

Derrick, M. ; Gan, K.K. ; Kooijman, P. ; et al.
Phys.Lett.B 166 (1986) 468-472, 1986.
Inspire Record 17510 DOI 10.17182/hepdata.30311

The ratio of differential cross sections for the reactions e + e − → γγ and e + e − → e + e − is measured at s = 29 GeV in the central polar angle region, |cos θ | < 0.55, and compared to the same ratio calculated by QED to order α 3 . The ratio of these ratios, integrated over this angular region, is 1.007±0.009±0.008, demonstrating excellent agreement between theory and experiment. The 95% confidence limits on the QED cut-off parameters for the γγ final state are Λ + > 59 GeV and Λ - > 59 GeV.

1 data table
Table 1

No description provided.


Observation of a New Charmed Meson.

The ARGUS collaboration Albrecht, H. ; Binder, U. ; Harder, G. ; et al.
Phys.Rev.Lett. 56 (1986) 549, 1986.
Inspire Record 222219 DOI 10.17182/hepdata.20225

Using the ARGUS detector at the DORIS II e+e− storage ring at DESY, we have obtained evidence for a new charmed resonance which decays into D*±(2010)π∓. The observed mass and width are 2420±6 MeV/c2 and 70±21 MeV/c2, respectively. The fragmentation function is found to be hard, as expected for a state containing a leading charm quark produced by nonresonant e+e− annihilation.

2 data tables
Table 1

No description provided.

Table 2

Estimated production cross section obtained by comparison with observed D*(2010) production rate.


New Results From Bhabha Scattering at 29-{GeV}

Derrick, M. ; Gan, K.K. ; Kooijman, P. ; et al.
Phys.Lett.B 166 (1986) 463-467, 1986.
Inspire Record 17511 DOI 10.17182/hepdata.6636

Results are reported on a high statistics study of Bhabha scattering at 29 GeV in the polar angle region, |cos θ | < 0.55. The data are consistent with the standard model, and measure vector and axial-vector coupling constants of g v 2 = 0.03 ± 0.09 and g a 2 = 0.46±0.14. Limits on the QED-cutoff parameters are Λ + > 154 GeV and Λ - > 220 GeV. Lower limits on scale parameters of composite models are in the range 0.9–2.8 TeV. The partial width of a hypothetical spin-zero boson decaying to e + e − has an upper limit which varies from 6 to 57 MeV corresponding to a boson mass in the range 45–80 GeV/ c 2 .

2 data tables
Table 1

No description provided.

Table 2

No description provided.


Tests of the Standard Model in Leptonic Reactions at {PETRA} Energies

The JADE collaboration Bartel, W. ; Becker, L. ; Cords, D. ; et al.
Z.Phys.C 30 (1986) 371, 1986.
Inspire Record 222566 DOI 10.17182/hepdata.48419

An analysis of the three leptonic reactionse+e−→e+e−,μ+μ− andτ+τ− over a wide range of energy,\(12< \sqrt s< 46.78 GeV\) is presented. The data were obtained with the JADE detector at thee+e− storage ring PETRA. They are compared to predictions of electroweak theories, in particular the standard model. For the total cross-sections of all three reactions and for the differential cross-section of Bhabha scattering no deviation from QED is found over the entire energy range. The differential cross-sections of μ and τ pairs at high energies show the angular asymmetry predicted by electroweak interference. The axial-vector and vector weak coupling constant, sin2θW andMZ are determined and compared to other measurements. Finally, limits on deviations from the standard model are given.

36 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

More…

Comparison of Charged Particle Multiplicities in Quark and Gluon Jets Produced in $e^+ e^-$ Annihilation at 29-{GeV}

Derrick, M. ; Gan, K.K. ; Kooijman, P. ; et al.
Phys.Lett.B 165 (1985) 449-453, 1985.
Inspire Record 17442 DOI 10.17182/hepdata.30286

The charged particle multiplicities of the quark and gluon jets in the three-fold symmetric e + e − → q q g events at √ s = 29 GeV have been studied using the high resolution spectrometer at PEP. A value of 〈 n 〉 g = 6.7 −2.1 +1.1 ±1.0 for gluon jet s with an energy of 9.7 −2.0 +1.5 GeV is measured. The ratio, 〈 n 〉 g /〈 n 〉 q , is 1.29 −0.41 +0.21 ±0.20, which i s significantly lower than the value of 9 4 naively expected from the ration of the gluon-to-quark color charges.

1 data table
Table 1

Mean jet charged particle interpretations for gluon and quark jets as described above.


rivet Analysis
Inclusive $\phi$ Production in $B$ Meson Decay

The CLEO collaboration Bortoletto, D. ; Chen, A. ; Garren, L. ; et al.
Phys.Rev.Lett. 56 (1986) 800, 1986.
Inspire Record 218314 DOI 10.17182/hepdata.20228

We have measured the inclusive branching ratio for B→φX to be 0.023±0.006±0.005. The momentum distribution of the φ mesons is compared with that expected from the cascade decays B→F→φ and B→D→φ. .AE

3 data tables
Table 1

DATA SAMPLE CONSISTED OF 30.4 1/PB. DATA TAKEN ON THE PEAK OF THE UPSI(10575).

Table 2

CONTINUUM DATA SAMPLE CONSISTED OF 12.8 1/PB. ENERGY JUST BELOW THE UPSI(10575).

Table 3

69970 B BBAR EVENTS.


Inclusive Charged Particle Production Near the Kinematic Limit in $e^+ e^-$ Annihilation at 29-{GeV}

Derrick, M. ; Kooijman, P. ; Loos, J.S. ; et al.
Phys.Lett.B 164 (1985) 199-202, 1985.
Inspire Record 17255 DOI 10.17182/hepdata.30327

Inclusive production of charged particles has been studied in e + e − annihilation at s s=29 GeV using the high resolution spectrometer at PEP. Differential cross sections are presented in the range of scaled energy 0.1< z <1.0. The data for z <0.5 show the (1− z ) 2 behavior predicted by the dimensional counting rules. Comparisons are made with predictions of the Lund string model and the Webber cluster model.

1 data table
Table 1

Data requested from authors.