Berardo, P.A.
ALPHAE
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Measurement of the running of the fine structure constant

The L3 collaboration Acciarri, M. ; Achard, P. ; Adriani, O. ; et al.
Phys.Lett.B 476 (2000) 40-48, 2000.
Inspire Record 523920 DOI 10.17182/hepdata.50032

Bhabha scattering data recorded at \sqrt{s}=189 GeV by the L3 detector at LEP are used to measure the running of the effective fine-structure constant for spacelike momentum transfers. The results are alpha^-1(-2.1 GeV^2) - alpha^-1(-6.25 GeV^2) = 0.78 +/- 0.26 alpha^-1(-12.25 GeV^2) - alpha^-1(-3434 GeV^2) = 3.80 +/- 1.29, in agreement with theoretical predictions.

3 data tables
Table 1

No description provided.

Table 2

Results extracted from the small angle Bhabha scattering sample at Z peak. Results contained total experimental uncertainty.

Table 3

Results extracted from the large angle Bhabha scattering sample at sqrt(s) = 189 GeV. Results contained total experimental and theoretical uncertainty.


Tests of the standard model and constraints on new physics from measurements of fermion pair production at 130-GeV to 172-GeV at LEP

The OPAL collaboration Ackerstaff, K. ; Alexander, G. ; Allison, John ; et al.
Eur.Phys.J.C 2 (1998) 441-472, 1998.
Inspire Record 447186 DOI 10.17182/hepdata.47404

Production of events with hadronic and leptonic final states has been measured in e^+e^- collisions at centre-of-mass energies of 130-172 GeV, using the OPAL detector at LEP. Cross-sections and leptonic forward-backward asymmetries are presented, both including and excluding the dominant production of radiative Z \gamma events, and compared to Standard Model expectations. The ratio R_b of the cross-section for bb(bar) production to the hadronic cross-section has been measured. In a model-independent fit to the Z lineshape, the data have been used to obtain an improved precision on the measurement of \gamma-Z interference. The energy dependence of \alpha_em has been investigated. The measurements have also been used to obtain limits on extensions of the Standard Model described by effective four-fermion contact interactions, to search for t-channel contributions from new massive particles and to place limits on chargino pair production with subsequent decay of the chargino into a light gluino and a quark pair.

15 data tables
Table 1

SIG(C=MEAS) and SIG(C=CORR) stand for measured values without (C=MEAS) and with (C=CORR) correction for interference between initial- and final-state radiation.

Table 2

The angular distribution of the thrust axis. Errors include statistical and systematic effects combined, with the former dominant.

Table 3

The measured values include the effect of interference between initial- andfinal-state radiation.

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