Measurement of the triple gluon vertex from double quark tagged 4-jet events

Abreu, P.; Gil, E. Cortina

doi:10.1016/s0370-2693(97)01192-1

Cited by 12 publications

(3 citation statements)

References 17 publications

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“…The DELPHI Collaboration [42] also performed this analysis with b-tagging to separate quark jets from gluon jets which increases sensitivity. The OPAL Collaboration fitted the LO prediction to a three-dimensional distribution of the cos Θ NR , cos α 34 and cos χ BZ variables [13].…”

Section: Resultsmentioning

confidence: 99%

A simultaneous measurement of the QCD colour factors and the strong coupling

Abbiendi¹,

Ainsley²,

Åkesson³

et al. 2001

Eur. Phys. J. C

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Using data from e + e − annihilation into hadrons, taken with the OPAL detector at LEP at the Z pole between 1991 and 1995, we performed a simultaneous measurement of the colour factors of the underlying gauge group of the strong interaction, C F and C A , and the strong coupling, α s . The measurement was carried out by fitting next-to-leading order perturbative predictions to measured angular correlations of 4-jet events together with multi-jet related variables. Our results, C A = 3.02 ± 0.25(stat.) ± 0.49(syst.) , C F = 1.34 ± 0.13(stat.) ± 0.22(syst.) , α s (M Z ) = 0.120 ± 0.011(stat.) ± 0.020(syst.) , provide a test of perturbative QCD in which the only assumptions are non-abelian gauge symmetry and standard hadronization models. The measurements are in agreement with SU(3) expectations for C F and C A and the world average of α s (M Z ).

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Section: Resultsmentioning

confidence: 99%

A simultaneous measurement of the QCD colour factors and the strong coupling

Abbiendi¹,

Ainsley²,

Åkesson³

et al. 2001

Eur. Phys. J. C

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“…In the past decade, precision measurements, especially in e + e − annihilation, have established both the gauge group structure underlying QCD [7,8,9,10,11] and the running of its coupling constant α s over a wide range of scales [12]. In a similar way, also the quark masses should vary with the scale.…”

mentioning

confidence: 99%

“…(9). Similarly, for every heavy quark Q occurring in a splitting g → QQ, the integrated splitting function Γ f is modified correspondingly.…”

mentioning

confidence: 99%

Resummed jet rates for e+e− annihilation into massive quarks

Krauss¹,

Rodrigo²

2003

Physics Letters B

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Expressions for Sudakov form factors for heavy quarks are presented. They are used to construct resummed jet rates for up to four jets in e + e − annihilation. The coefficients of leading and nextto-leading logarithmic corrections, mandatory for a combination with higher order matrix elements, are evaluated up to second order in αs.PACS numbers: 12.38. Bx, 12.38.Cy, 13.66.Bc, 14.65.Fy The formation of jets is the most prominent feature of perturbative QCD in e + e − annihilation into hadrons. Jets can be visualized as large portions of hadronic energy or, equivalently, as a set of hadrons confined to an angular region in the detector. In the past, this qualitative definition was replaced by quantitatively precise schemes to define and measure jets, such as the cone algorithms of the Weinberg-Sterman [1] type or clustering algorithms, e.g. the Jade [2,3] or the Durham scheme (k ⊥ scheme) [4]. A refinement of the latter one is provided by the Cambridge algorithm [5]. Within the context of this paper, however, the Durham and the Cambridge algorithms are equivalent and they will be referred to as k ⊥ algorithm. A clustering according to the relative transverse momenta has a number of properties that minimize the effect of hadronization corrections and allow an exponentiation of leading (LL) and next-to-leading logarithms (NLL) [4,6] stemming from soft and collinear emission of secondary partons.Equipped with a precise jet definition the determination of jet production cross sections and their intrinsic properties is one of the traditional tools to investigate the structure of the strong interaction and to deduce its fundamental parameters. In the past decade, precision measurements, especially in e + e − annihilation, have established both the gauge group structure underlying QCD [7,8,9,10,11] and the running of its coupling constant α s over a wide range of scales [12]. In a similar way, also the quark masses should vary with the scale.A typical strategy to determine the mass of, say, the bottom-quark at the centre-of-mass (c.m.) energy of the collider is to compare the ratio of three-jet production cross sections for heavy and light quarks [13,14,15,16,17]. At jet resolution scales below the mass of the quark, i.e. for gluons emitted by the quark with a relative transverse momentum k ⊥ smaller than the mass, the collinear divergences are regularized by the quark mass. In this region mass effects are enhanced by logarithms ln(m b /k ⊥ ), increasing the significance of the measurement. Indeed, this leads to a multiscale problem since in this kinematical region also large logarithms ln( √ s/k ⊥ ) appear such that both logarithms need to be resummed simultaneously. A solution to a somewhat similar two-scale problem, namely for the average subjet multiplicities in two-and three-jet events in e + e − annihilation was given in [35]. These large logarithms can be deduced by inspection of the corresponding splitting functions for massive quarks [18,19,20,21,22] and of the boundaries for their integration over the energy...

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Higher twist contributions to R-hadron phenomenology in the light gluino scenario

2000

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The open light gluino window allows non-trivial higher twist gluino contributions to the proton wave function. Using a two-component model originally developed for charm hadroproduction, higher twist intrinsic gluino contributions to final state R-hadron formation are shown to enhance leading twist production in the forward x F region. We calculate R-hadron production at p lab = 800 GeV in pp, pBe, and pCu interactions with light gluino masses of 1.2, 1.5, 3.5, and 5.0 GeV.

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Measurement of the triple gluon vertex from double quark tagged 4-jet events

Cited by 12 publications

References 17 publications

A simultaneous measurement of the QCD colour factors and the strong coupling

A simultaneous measurement of the QCD colour factors and the strong coupling

Resummed jet rates for e+e− annihilation into massive quarks

Higher twist contributions to R-hadron phenomenology in the light gluino scenario

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