Publications by Giulia Zanderighi

Four-fermion production near the W pair-production threshold

Nuclear Physics B 792 (2008) 89-135

M Beneke, P Falgari, C Schwinn, A Signer, G Zanderighi

We perform a dedicated study of the four-fermion production process e- e+ → μ- over(ν, ̄)μ u over(d, ̄) X near the W pair-production threshold in view of the importance of this process for a precise measurement of the W boson mass. Accurate theoretical predictions for this process require a systematic treatment of finite-width effects. We use unstable-particle effective field theory (EFT) to perform an expansion in the coupling constants, ΓW / MW, and the non-relativistic velocity v of the W boson up to next-to-leading order in ΓW / MW ∼ αew ∼ v2. We find that the dominant theoretical uncertainty in MW is currently due to an incomplete treatment of initial-state radiation. The remaining uncertainty of the NLO EFT calculation translates into δ MW ≈ 10 - 15   MeV, and to about 5 MeV with additional input from the NLO four-fermion calculation in the full theory. © 2007 Elsevier B.V. All rights reserved.

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