Electroweak radiative corrections in Z-boson decays

Высоцкий, Михаил Иосифович; Novikov, V.A.; Okun, L.B.; Rozanov, Alexandre

doi:10.3367/ufnr.0166.199605e.0539

Cited by 11 publications

(10 citation statements)

References 123 publications

(19 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where A e is the corresponding asymmetry parameter for the electron [34]. We only consider the parameter A b since A e , and hence A 0,b F B itself, would involve contribution from the fourth generation lepton sector, while we would like to restrict ourselves to the quark sector in this paper.…”

Section: B Unitarity Of the Ckm4 Matrixmentioning

confidence: 99%

Constraints on the four-generation quark mixing matrix from a fit to flavor-physics data

2011

View full text Add to dashboard Cite

In the scenario with four quark generations, we perform a fit using flavor-physics data and determine the allowed values -preferred central values and errors -of all of the elements of the 4 × 4 quark mixing matrix. In addition to the direct measurements of some of the elements, we include in the fit the present measurements of several flavorchanging observables in the K and B systems that have small hadronic uncertainties, and also consider the constraints from the vertex corrections to Z → bb. The values taken for the masses of the fourth-generation quarks are consistent with the measurements of the oblique parameters and perturbativity of the Yukawa couplings. We find that | V tb | ≥ 0.98 at 3σ, so that a fourth generation cannot account for any large deviation of |V tb | from unity. The fit also indicates that all the new-physics parameters are consistent with zero, and the mixing of the fourth generation with the other three is constrained to be small:

show abstract

Section: B Unitarity Of the Ckm4 Matrixmentioning

confidence: 99%

Constraints on the four-generation quark mixing matrix from a fit to flavor-physics data

2011

View full text Add to dashboard Cite

show abstract

“…The explicit form of the functions H i is given in refs. [41,42] and their numerical values for various values of m H are given in Table 3. The constants C i in eq.…”

Section: The Functionsmentioning

confidence: 99%

“…Due to asymptotic freedom of QCD [40] these corrections were calculated in perturbation theory. The analytical expressions for corrections δ q 2 V i and δ t 2 V i (t) are given in [41,42]. Here we only give numerical estimates for them,…”

Section: Corrections δV I (T)mentioning

confidence: 99%

Theory ofZboson decays

Novikov¹,

Okun²,

Rozanov

et al. 1999

Rep. Prog. Phys.

View full text Add to dashboard Cite

The precision data on Z boson decays from LEP-I and SLC colliders are compared with the predictions based on the Minimal Standard Theory. The Born approximation of the theory is based on three most accurately known observables: G µ -the four fermion coupling constant of muon decay, m Z -the mass of the Z boson, and α(m Z ) -the value of the "running fine structure constant" at the scale of m Z . The electroweak loop corrections are expressed, in addition, in terms of the masses of higgs, m H , of the top and bottom quarks, m t and m b , and of the strong interaction constant α s (m Z ). The main emphasis of the review is focused on the one-electroweak-loop approximation. Two electroweak loops have been calculated in the literature only partly. Possible manifestations of new physics are briefly discussed. Contents.1. Introduction. Basic parameters of the theory.3. Amplitudes, widths, and asymmetries.4. One-loop corrections to hadronless observables.4.1 Four types of Feynman diagrams. 4.2 The asymptotic limit at m 2 t ≫ m 2 Z . 4.3 The functions V m (t, h), V A (t, h) and V R (t, h). 4.4 Corrections δV i (t). 4.5 Accidental (?) compensation and the mass of the t-quark. 4.6 How to calculate V i ? 'Five steps'.

show abstract

“…This effect has been proved by high-energy experiments in accelerators. For example, the finestructure constant α = e 2 /hc equals 1/137.036 at low energies (E → 0), but increases up-to 1/128.896 for energy E ∼ 90 GeV (Vysotsky et al 1996). Such "running" of the constants has to be taken into account in any consideration of the very early Universe.…”

Section: Introductionmentioning

confidence: 99%

Do the fundamental constants vary in the course of cosmological evolution?

Ivanchik

Rodriguez²,

Petitjean³

et al. 2002

Astron. Lett.

View full text Add to dashboard Cite

-We estimate the cosmological variation of the proton-to-electron mass ratio µ = m p /m e by measuring the wavelengths of molecular hydrogen transitions in the early universe. The analysis is performed using high spectral resolution observations (F W HM ≈ 7 km/s) of two damped Lyman-α systems at z abs = 2.3377 and 3.0249 observed along the lines of sight to the quasars Q 1232+082 and Q 0347−382 respectively.The most conservative result of the analysis is a possible variation of µ over the last ∼10 Gyrs, with an amplitude ∆µ/µ = (5.7 ± 3.8) × 10 −5 .The result is significant at the 1.5σ level only and should be confirmed by further observations. This is the most stringent estimate of a possible cosmological variation of µ obtained up to now.

show abstract

Electroweak radiative corrections in Z-boson decays

Cited by 11 publications

References 123 publications

Constraints on the four-generation quark mixing matrix from a fit to flavor-physics data

Constraints on the four-generation quark mixing matrix from a fit to flavor-physics data

Theory ofZboson decays

Do the fundamental constants vary in the course of cosmological evolution?

Contact Info

Product

Resources

About