Three-jet production at LEP and the bottom quark mass

Bilenky, M. S.; Rodrigo, Germán; Santamaría, Arcadi

doi:10.1016/0550-3213(94)00586-4

Cited by 35 publications

(46 citation statements)

References 36 publications

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“…[9,70,[334][335][336][337][338], and for a heavy-quark-pair plus up to one jet in refs. [339][340][341][342][343][344][345]. All other processes are computed here for the first time at the NLO.…”

Section: Jhep07(2014)079mentioning

confidence: 99%

The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations

Alwall

Frederix

Frixione

et al. 2014

J. High Energ. Phys.

6,069

5,572

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We discuss the theoretical bases that underpin the automation of the computations of tree-level and next-to-leading order cross sections, of their matching to parton shower simulations, and of the merging of matched samples that differ by light-parton multiplicities. We present a computer program, MadGraph5 aMC@NLO, capable of handling all these computations -parton-level fixed order, shower-matched, merged -in a unified framework whose defining features are flexibility, high level of parallelisation, and human intervention limited to input physics quantities. We demonstrate the potential of the program by presenting selected phenomenological applications relevant to the LHC and to a 1-TeV e + e − collider. While next-to-leading order results are restricted to QCD corrections to SM processes in the first public version, we show that from the user viewpoint no changes have to be expected in the case of corrections due to any given renormalisable Lagrangian, and that the implementation of these are well under way.

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Section: Jhep07(2014)079mentioning

confidence: 99%

The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations

Alwall

Frederix

Frixione

et al. 2014

J. High Energ. Phys.

6,069

5,572

View full text Add to dashboard Cite

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“…The mass of the heavy quark m b identified with the b quark at LEP energies becomes an additional parameter of the theory and is subject to renormalisation analogously to the strong coupling constant. The mass of the b quark m b is experimentally accessible in hadronic Z 0 decays, because i) about 21% of the decays are Z 0 → bb and these events can be identified with high efficiency and purity, ii) event samples of O(10 6 ) events are available and iii) observables like the 3-jet rate R 3 (y cut ) in the JADE or Durham algorithm can have enhanced mass effects going like m 2 b /m 2 Z 0 /y cut [219]. In the experimental analyses [220][221][222][223][224] the ratio B 3 = R b 3 /R l 3 , R b 3 (R l 3 ) are the 3-jet rates in b quark (light quark) events, is studied which reduces the influence of common systematics.…”

Section: Running B Quark Massmentioning

confidence: 99%

Tests of quantum chromo dynamics at e⁺e⁻ colliders

Kluth¹

2006

Rep. Prog. Phys.

107

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Abstract.The current status of tests of the theory of strong interactions, Quantum Chromo Dynamics (QCD), with data from hadron production in e + e − annihilation experiments is reviewed. The LEP experiments ALEPH, DELPHI, L3 and OPAL have published many analyses with data recorded on the Z 0 resonance at √ s = 91.2 GeV and above up to √ s > 200 GeV. There are also results from SLD at √ s = 91.2 GeV and from reanalysis of data recorded by the JADE experiment at 14 ≤ √ s ≤ 44 GeV. The results of studies of jet and event shape observables, of particle production and of quark gluon jet differences are compared with predictions by perturbative QCD calculations. Determinations of the strong coupling constant α S (m Z 0 ) from jet and event shape observables, scaling violation and fragmentation functions, inclusive observables from Z 0 decays, hadronic τ decays and hadron production in low energy e + e − annihilation are discussed. Updates of the measurements are performed where new data or improved calculations have become available. The best value of α S (m Z 0 ) is obtained from an average of measurements using inclusive observables calculated in NNLO QCD: α S (m Z 0 ) = 0.1211 ± 0.0021 where the error is dominated by theoretical systematic uncertainties. The other measurements of α S (m Z 0 ) are in good agreement with this value. Finally, investigations of the gauge structure of QCD are summarised and the best values for the colour factors are determined: C A = 2.89 ± 0.21 C F = 1.30 ± 0.09 with errors dominated by systematic uncertainties and in good agreement with the expectation from QCD with the SU(3) gauge symmetry.

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“…For detailed investigations of b jets quark mass effects must be taken into account in the theoretical predictions [10]. Specifically, knowledge of the NLO three-jet fraction for non-zero quark mass opens the possibility to measure the mass of the b quark from b jet data at the Z peak [11]. Further applications include precision tests of the asymptotic freedom property of QCD by means of three-jet rates measured at various center-of-mass energies, also far below the Z resonance [12].…”

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confidence: 99%

Next-to-Leading Order QCD Corrections to Three-Jet Cross Sections with Massive Quarks

1997

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We calculate the cross section for e + e − annihilation into three jets for massive quarks at next-to-leading order in perturbative QCD, both on and off the Z resonance. Our computation allows the implementation of any jet clustering algorithm. We give results for the three-jet cross section involving b quarks for the JADE and Durham algorithm at c.m. energies √ s = m Z . We also discuss a three-jet observable that is sensitive to the mass of the b quark. PACS number(s): 12.38. Bx, 13.87.Ce, 14.65.Fy Typeset using REVT E X * supported by BMBF, contract 057AC9EP(1). † supported by Deutsche Forschungsgemeinschaft. 1Jets of hadrons, which originate from the production and subsequent fragmentation of quarks and gluons in high energy electron positron annihilation have been among the key predictions [1,2] of quantum chromodynamics (QCD). For precision tests of QCD the e + e − experiments provide a particularily clean set-up. There exist a number of jet observables that are well-defined (i.e., infrared-finite) in QCD, and which can be calculated perturbatively as an expansion in the strong coupling α s . The next-to-leading order (NLO) QCD corrections to three-jet production were computed more than a decade ago [3,4] for massless quarks, and subsequent implementations [5-9] of these results have been widely used for tests of QCD with jet physics.To date huge samples of jet events produced at the Z resonance have been collected both at LEP and SLC. From these data large numbers of jet events involving b quarks can be isolated with high purity using vertex detectors. For detailed investigations of b jets quark mass effects must be taken into account in the theoretical predictions [10]. Specifically, knowledge of the NLO three-jet fraction for non-zero quark mass opens the possibility to measure the mass of the b quark from b jet data at the Z peak [11]. Further applications include precision tests of the asymptotic freedom property of QCD by means of three-jet rates measured at various center-of-mass energies, also far below the Z resonance [12].As far as massive quarks are concerned the three, four, and five jet rates are known to leading order (LO) in α s only [13][14][15]. In this Letter we report the calculation of the e + e − annihilation cross section into three jets involving a massive quark antiquark pair at next-to-leading order QCD [16,17]. The determination of this cross section σ 3 N LO to order α 2 s consists of two parts: First, the computation of the amplitude of the partonic reaction e + e − → γ * , Z * → QQg at leading and next-to-leading order in the QCD coupling. Here Q denotes a massive quark and g a gluon. We have calculated the complete decay amplitude and decay distribution structure for this reaction. This allows for predictions including oriented three-jet events. The differential cross section involves the so-called hadronic tensor 2 which contains five parity-conserving and four parity-violating Lorentz structures. Second, the leading order matrix elements of the four-parton product...

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Three-jet production at LEP and the bottom quark mass

Cited by 35 publications

References 36 publications

The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations

The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations

Tests of quantum chromo dynamics at e⁺e⁻ colliders

Next-to-Leading Order QCD Corrections to Three-Jet Cross Sections with Massive Quarks

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Three-jet production at LEP and the bottom quark mass

Cited by 35 publications

References 36 publications

The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations

The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations

Tests of quantum chromo dynamics at e+e− colliders

Next-to-Leading Order QCD Corrections to Three-Jet Cross Sections with Massive Quarks

Contact Info

Product

Resources

About

Tests of quantum chromo dynamics at e⁺e⁻ colliders