Decoupling relations to O(αs3) and their connection to low-energy theorems

We construct approximate formulas for the O(α 3 s ) QCD contributions to vector, axial-vector, scalar and pseudo-scalar quark current correlators, which are valid for arbitrary values of momenta and masses. The derivation is based on conformal mapping and the Padé approximation procedure and incorporates known expansions in the low energy, threshold and high energy regions. We use our results to estimate additional terms in these expansions.

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“…s (m) at the scale of the pole mass. Hence we re-express the effective coupling using the decoupling relation [52,53] …”

Section: A Threshold Expansionmentioning

confidence: 99%

Reconstruction of heavy quark current correlators at

et al. 2009

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“…where the coefficient is given in the MS scheme, in terms of α s for five active flavors, by [53,54,55,56,57,58] …”

Section: Corrections To Field Strength Operatorsmentioning

confidence: 99%

Higgs-Higgs bound state due to new physics at a TeV

2007

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We examine the effects of new physics on the Higgs sector of the standard model, focusing on the effects on the Higgs self couplings. We demonstrate that a low mass higgs, m h < 2 m t , can have a strong effective self coupling due to the effects of a new interaction at a TeV. We investigate the possibility that the first evidence of such an interaction could be a higgs-higgs bound state.To this end, we construct an effective field theory formalism to examine the physics of such a low mass higgs boson. We explore the possibility of a non relativistic bound state of the higgs field (Higgsium) at LHC and construct a non relativistic effective field theory of the higgs sector that is appropriate for such studies (NRHET).

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“…These constants are universal and have been computed in the case of QCD up to order α 3 s [49]. Concerning the practical consequences we again want to consider the example of e + e − annihilation.…”

Section: Decoupling Of Heavy Particlesmentioning

confidence: 99%

Results and techniques of multi-loop calculations

Steinhauser

2002

Physics Reports

100

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In this review some recent multi-loop results obtained in the framework of perturbative Quantum Chromodynamics (QCD) and Quantum Electrodynamics (QED) are discussed. After reviewing the most advanced techniques used for the computation of renormalization group functions, we consider the decoupling of heavy quarks. In particular, an effective method for the evaluation of the decoupling constants is presented and explicit results are given. Furthermore the connection to observables involving a scalar Higgs boson is worked out in detail. An all-order low energy theorem is derived which establishes a relation between the coefficient functions in the hadronic Higgs decay and the decoupling constants. We review the radiative corrections of a Higgs boson into gluons and quarks and present explicit results up to order α 4 s and α 3 s , respectively. In this review special emphasis is put on the applications of asymptotic expansions. A method is described which combines expansion terms of different kinematical regions with the help of conformal mapping and Padé approximation. This method allows us to proceed beyond the present scope of exact multi-loop calculations. As far as physical processes are concerned, we review the computation of three-loop current correlators in QCD taking into account the full mass-dependence. In particular, we concentrate on the evaluation of the total cross section for the production of hadrons in e + e − annihilation. The knowledge of the complete mass dependence at order α 2 s has triggered a bunch of theory-driven analyses of the hadronic contribution to the electromagnetic coupling evaluated at high energy scales. The status is summarized in this review. In a further application four-loop diagrams are considered which contribute to the order α 2 QED corrections to the µ decay. Its relevance for the determination of the Fermi constant G F is discussed. Finally the calculation of the three-loop relation between the MS and on-shell quark mass definitions is presented and physical applications are given. To complete the presentation, some technical details are presented in the Appendix, where also explicit analytical results are listed.

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Decoupling relations to O(αs3) and their connection to low-energy theorems

Cited by 286 publications

References 66 publications

Reconstruction of heavy quark current correlators at

Reconstruction of heavy quark current correlators at

Higgs-Higgs bound state due to new physics at a TeV

Results and techniques of multi-loop calculations

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