Two-photon production processes at high energy. I

Bhattacharya, R.; Smith, J.; Grammer, G.

doi:10.1103/physrevd.15.3267

Cited by 88 publications

(50 citation statements)

References 12 publications

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“…For two-photon processes, the PHOJET [15], PYTHIA [14], and HERWIG [16] generators have been used to simulate hadronic final states. The Vermaseren [17] generator has been used to estimate the background contribution from all two-photon e + e − ℓ + ℓ − final states. All other four-fermion final states have been simulated with grc4f [18].…”

Section: Monte Carlo Simulationmentioning

confidence: 99%

Search for doubly charged Higgs bosons with the OPAL detector at LEP

et al. 2002

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A search for pair-produced doubly charged Higgs bosons has been performed using data samples corresponding to an integrated luminosity of about 614 pb −1 collected with the OPAL detector at LEP at centre-of-mass energies between 189 GeV and 209 GeV. No evidence for a signal has been observed. A mass limit of 98.5 GeV/c 2 at the 95% confidence level has been set for the doubly charged Higgs particle in left-right symmetric models. This is the first search for doubly charged Higgs bosons at centre-of-mass energies larger than 91 GeV.To be submitted to Phys. Lett. B

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Section: Monte Carlo Simulationmentioning

confidence: 99%

Search for doubly charged Higgs bosons with the OPAL detector at LEP

et al. 2002

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“…Non-τ background sources such as Bhabha, µ-pair and two-photon events have been generated using the babamc [33,34], koralz [35] and vermaseren [36,37] generators, respectively. The response of the detector to generated particles is modeled using a simulation program [38] based on the geant [39] package.…”

Section: Monte Carlo Simulated Samplesmentioning

confidence: 99%

Measurement of the Michel parameters in leptonic tau decays

al.

1999

Eur. Phys. J. C

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The Michel parameters of the leptonic τ decays are measured using the OPAL detector at LEP. The parameters ρ ℓ , ξ ℓ , (ξδ) ℓ (with ℓ = e, µ) and η µ are extracted from the energy spectra of the charged decay leptons and from their energy-energy correlations. A new method involving a global likelihood fit of Monte Carlo generated events with complete detector simulation and background treatment has been applied to the data recorded at center-of-mass energies close to √ s = m Z 0 corresponding to an integrated luminosity of 155 pb −1 . If e-µ universality is assumed and inferring the τ polarization from neutral current data, the measured Michel parameters are: ρ = 0.781 ± 0.028 ± 0.018, ξ = 0.98 ± 0.22 ± 0.10, η = 0.027 ± 0.055 ± 0.005, ξδ = 0.65 ± 0.14 ± 0.07, where the value of η has been constrained using the published OPAL measurements of the leptonic branching ratios and the τ lifetime. Limits on non-standard coupling constants and on the masses of new gauge bosons are obtained. The results are in agreement with the V−A prediction of the Standard Model.

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“…For the two-photon background, the PYTHIA [19], PHOJET [20] and HERWIG [21] Monte Carlo generators have been used for e + e − qq final states and the Vermaseren [22] generator for all e + e − ℓ + ℓ − final states. All other four-fermion final states have been simulated with grc4f [23], which takes into account interferences between all four-fermion diagrams.…”

Section: Monte Carlo Simulationmentioning

confidence: 99%

Search for stable and long-lived massive charged particles in e+e− collisions at =130−183 GeV

et al. 1998

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A search for stable and long-lived massive particles of electric charge |Q/e| = 1 or 2/3, pair-produced in e + e − collisions at centre-of-mass energies from 130 to 183 GeV, is reported by the OPAL collaboration at LEP. No evidence for production of these particles was observed in a mass range between 45 and 89.5 GeV. Model-independent upper limits on the production cross-section between 0.05 and 0.19 pb have been derived for scalar and spin-1/2 particles with charge ±1. Within the framework of the minimal supersymmetric model (MSSM), this implies a lower limit of 82.5 (83.5) GeV on the mass of long-lived right-(left-)handed scalar muons and scalar taus. Long-lived charged leptons and charginos are excluded for masses below 89.5 GeV. For particles with charge ±2/3 the upper limits on the production cross-section vary between 0.05 and 0.2 pb. All limits, on masses and on cross-sections, are valid at the 95% confidence level for particles with lifetimes longer than 10 −6 s.

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Two-photon production processes at high energy. I

Cited by 88 publications

References 12 publications

Search for doubly charged Higgs bosons with the OPAL detector at LEP

Search for doubly charged Higgs bosons with the OPAL detector at LEP

Measurement of the Michel parameters in leptonic tau decays

Search for stable and long-lived massive charged particles in e+e− collisions at =130−183 GeV

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