TWOGEN—a simple Monte Carlo generator for two-photon reactions

Buijs, A.; Langeveld, W. G.J.; Lehto, Markku; Miller, D. J.

doi:10.1016/0010-4655(94)90191-0

Cited by 41 publications

(32 citation statements)

References 21 publications

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“…Backgrounds from processes with four fermions in the final state were evaluated using grc4f, Excalibur and Fermisv [23]. Backgrounds from two-photon processes were evaluated using Pythia, Herwig, Phojet [24], Twogen [25] and the Vermaseren program [26]. At least two independent Monte Carlo estimates were available for each category of two-photon and four-fermion background.…”

Section: Data and Monte Carlomentioning

confidence: 99%

Measurement of the W boson mass and ${\rm W^+W^-}$ production and decay properties in ${\rm e}^+{\rm e}^-$ collisions at ${\sqrt s = 172}$ GeV

al.

1998

Eur. Phys. J. C

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This paper describes the measurement of the W boson mass, M W , and decay width, Γ W , from the direct reconstruction of the invariant mass of its decay products in W pair events collected at a mean centre-of-mass energy of √ s=172.12 GeV with the OPAL detector at LEP. Measurements of the W pair production cross-section, the W decay branching fractions and properties of the W decay final states are also described. A total of 120 candidate W + W − events has been selected for an integrated luminosity of 10.36 pb −1 . The W + W − production cross-section is measured to be σ WW = 12.3±1.3(stat.) ±0.3(syst.) pb, consistent with the Standard Model expectation. The W + W − → qqℓν ℓ and W + W − → qqqq final states are used to obtain a direct measurement of Γ W = 1.30 +0.62 −0.55 (stat.) ± 0.18(syst.) GeV. Assuming the Standard Model relation between M W and Γ W , the W boson mass is measured to be M W = 80.32 ± 0.30(stat.) ± 0.09(syst.) GeV. The event properties of the fullyhadronic decays of W + W − events are compared to those of the semi-leptonic decays. At the current level of precision there is no evidence for effects of colour reconnection in the observables studied. Combining data recorded by OPAL at √ s ∼ 161-172 GeV, the W boson branching fraction to hadrons is determined to be 69.8 +3.0 −3.2 (stat.) ±0.7(syst.)%, consistent with the prediction of the Standard Model. The combined mass measurement from direct reconstruction and from the W + W − production crosssections measured at √ s ∼ 161 and √ s ∼ 172 GeV is M W = 80.35 ± 0.24(stat.) ± 0.07(syst.) GeV.

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Section: Data and Monte Carlomentioning

confidence: 99%

Measurement of the W boson mass and ${\rm W^+W^-}$ production and decay properties in ${\rm e}^+{\rm e}^-$ collisions at ${\sqrt s = 172}$ GeV

al.

1998

Eur. Phys. J. C

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“…For leptonic final states this problem does not arise and the Monte Carlo includes I/FSR interference. Four-fermion backgrounds are simulated using grc4f [17] or KORALW [18] with matrix elements from grc4f, and two-photon backgrounds using PHO-JET [19], PYTHIA, HERWIG, TWOGEN [20] and VERMASEREN [21]. For systematic studies of taupair backgrounds in the hadronic channel, the KO-RALZ [22] generator is also employed.…”

Section: Data and Monte Carlo Samplesmentioning

confidence: 99%

Determination of the LEP beam energy using radiative fermion-pair events

et al. 2004

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We present a determination of the LEP beam energy using "radiative return" fermion-pair events recorded at centre-of-mass energies from 183 to 209 GeV. We find no evidence of a disagreement between the OPAL data and the LEP Energy Working Group's standard calibration. Including the energy-averaged 11 MeV uncertainty in the standard determination, the beam energy we obtain from the OPAL data is higher than that obtained from the LEP calibration by 0 ± 34(stat.) ± 27(syst.) MeV.

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“…The events generated with HERWIG, PHOJET and Vermaseren are called two-photon events. An alternative hadronic two-photon sample for systematic studies has been generated using F2GEN [34] for Q 2 > 4.5 GeV 2 and PYTHIA for Q 2 < 4.5 GeV 2 . Other processes with four fermions in the final states, including W pair production, have been simulated with grc4f [35] and an alternative sample has been generated with KORALW [36].…”

Section: Kinematics and Monte Carlo Simulationsmentioning

confidence: 99%

Search for single leptoquark and squark production in electron-photon scattering at $\sqrt{s_{\rm ee}}=189$ GeV at LEP

Abbiendi¹,

Ainsley²,

Åkesson³

et al. 2002

Eur. Phys. J. C

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A search for first generation scalar and vector leptoquarks (LQ) as well as for squarks (q) in R-parity violating SUSY models has been performed using e + e − collisions collected with the OPAL detector at LEP at an e + e − centre-of-mass energy √ s ee of 189 GeV. The data correspond to an integrated luminosity of about 160 pb −1 . The dominant process for this search is eq → LQ/q → eq, νq, where a photon, which has been radiated by one of the beam electrons, serves as a source of quarks. The numbers of selected events found in the two decay channels are in agreement with the expectations from Standard Model processes. This result allows to set lower limits at the 95 % confidence level on the mass of first generation scalar and vector leptoquarks, and of squarks in R-parity violating SUSY models. For Yukawa couplings λ to fermions larger than √ 4πα em , the mass limits range from 121 GeV/c 2 to 175 GeV/c 2 (149 GeV/c 2 to 188 GeV/c 2 ) depending on the branching ratio β of the scalar (vector) leptoquark state. Furthermore, limits are set on the Yukawa couplings λ for leptoquarks and λ ′ 1jk for squarks, and on β as a function of the scalar leptoquark/squark mass.

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TWOGEN—a simple Monte Carlo generator for two-photon reactions

Cited by 41 publications

References 21 publications

Measurement of the W boson mass and ${\rm W^+W^-}$ production and decay properties in ${\rm e}^+{\rm e}^-$ collisions at ${\sqrt s = 172}$ GeV

Measurement of the W boson mass and ${\rm W^+W^-}$ production and decay properties in ${\rm e}^+{\rm e}^-$ collisions at ${\sqrt s = 172}$ GeV

Determination of the LEP beam energy using radiative fermion-pair events

Search for single leptoquark and squark production in electron-photon scattering at $\sqrt{s_{\rm ee}}=189$ GeV at LEP

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