Tests of the Standard Model and α(mZ2)
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Related Papers (5)
Frequently Asked Questions (6)
Q2. What is the effect of radiative corrections on the Z pole?
The precision of measurements to ∼10−3 exceeded sufficiently the natural size of genuine ElectroWeak (EW) correctionsα(m2Z) πsin2θ ∼ 1% (1)The notion of effective couplings has been introduced in which radiative corrections, both to the vertex and to the propagator, have been included.
Q3. What is the sms value at the Z pole?
The value of alpha at the Z pole, α(m2Z), is not any more 1/137.(), α(0), but 1/128.940±0.048, α(s), [2].α(s) = α(0)1 − Δαl(s) − Δα(5)had(s) − Δαt(s) (2)LAPP-EXP-2006-132
Q4. What is the contribution of the other 5 quark loops?
The contribution of the other 5 quark loops, ”hadronic contribution to the running of α”, Δα(5)had(m 2 Z) = 0.02758 ± 0.00035 [2] at the Z pole, is calculated by integrating the experimentally measured Rhad = σhadσµµ in e+e− annihilation (Fig. 3).
Q5. How much would the change in Rhad affect the central value of the Higgs mass?
the change Rhad by ±1σ in this c.m.s. energy region would shift the central value of the fitted Higgs mass by +16 −9 GeV.
Q6. What is the role of (m2Z) in the SM predictions?
The role of α(m2Z) in the SM fits can be understood from Fig. 2. If the value of α(m2Z) (star) is changed, the SM prediction is shifted with respect to the experimental results causing the change in3the prediction for the Higgs mass.