Current Algebra Approach to Heavy Top Effects in Z → b + b̄
نویسنده
چکیده
The O(α mt m2 W ) and O(ααs mt m2 W ) corrections to the partial decay width Γ(Z → b + b̄) are computed using the current algebra formulation of radiative corrections. This framework allows one to easily enforce the relevant Ward identity that greatly simplifies the calculations. As a result, the one-loop O(α mt m2 W ) contribution is computed through the investigation of only two convergent diagrams. The computation of the QCD corrections to the one-loop O(α mt m2 W ) term involves fewer diagrams than in the standard approach. In particular, the number of infrared divergent contribution is reduced. The calculation is performed in the dimensional regularization scheme and no term more divergent than 1 n−4 is found. Our result confirms the screening of the one-loop top mass effect recently found by Fleischer et al..
منابع مشابه
ar X iv : h ep - p h / 06 03 19 9 v 1 2 3 M ar 2 00 6 New signals in pair production of heavy Q = 2 / 3 singlets at LHC
New quark singlets T can be produced in pairs at LHC through standard QCD interactions, with a large cross section for masses of several hundreds of GeV. Their charged current decays T T̄ → W+bW−b̄, with semileptonic decay of the W pair, give a final state lνbb j j, as in top pair production. The mixed decay modes T T̄ → W+bHt̄,Ht W−b̄ → W+bW−b̄H, T T̄ → WbZt̄,Zt W−b̄ → W+bW−b̄Z, with H,Z → j j, yield tw...
متن کاملBeauty Quark Fragmentation Into Strange B Mesons
Using the recent measurement of the total production rate for Bs and B ∗ s mesons in electron-positron annihilation to determine the strange quark mass parameter in the b̄ → Bs, B ∗ s fragmentation functions we calculate the momentum distributions of the Bs and B ∗ s mesons. Internet address: [email protected] Internet address: [email protected] Recently the probability for a heavy qu...
متن کاملBeyond Leading Logarithms
The renormalization group evolution of ∆B = 2 transition operators is studied at leading order in heavy quark effective theory and at next-to-leading order in QCD. We calculate new contributions that were not taken into account in previous work and obtain the complete result to next-to-leading logarithmic accuracy. The various scheme and scale dependences and their cancellation in physical quan...
متن کاملNonperturbative Effects in B̄ → X s l + l − for Large Dilepton Invariant Mass
We reconsider the calculation of O(ΛQCD/mb) nonperturbative corrections to B̄ → Xsll decay. Our analysis confirms the results of Ali et al. for the dilepton invariant mass spectrum, which were in disagreement with an earlier publication, and for the lepton forward-backward asymmetry. We also give expressions for the O(ΛQCD/mb) corrections to the left-right asymmetry. In addition we discuss the b...
متن کاملStrange–beauty Meson Production by Fragmentation in Proton–antiproton Collisions *
The cross sections for the production of Bs and B ∗ s mesons through the fragmentation process in p̄p collisions were calculated. The input parameters were determined from the measured Bs and B ∗ s production rates in e e annihilation. The transverse momentum distributions dσ/dpT are given for √ s = 1.8 TeV, the Fermilab Tevatron energy. At LEP the DELPHI Collaboration has measured the probabili...
متن کامل