Electroweak Precision Data - Global Higgs Analysis

TL;DR

The paper synthesizes precision electroweak data up to early 2003 to test the Standard Model and constrain its parameters, notably the Higgs mass. It combines Z-pole observables, W and top masses, neutrino scattering, and atomic parity-violation into a global SM fit, highlighting a preference for a light Higgs while revealing modest tensions, particularly from NuTeV and A_FB^{0,b}. The analysis underscores the interplay between experimental precision and theoretical radiative corrections, and it discusses caveats in the low-Higgs-mass region. Overall, the measurements largely corroborate the SM, with two notable anomalies guiding future improvements in theory and measurement precision.

Abstract

The status of published and preliminary precision electroweak measurements as of winter 2002/03 is presented. The new results on the mass of the W boson as measured at LEP-2 and on atomic parity violation in Caesium are included. The experimental results are compared with the predictions of the minimal Standard Model and are used to constrain its parameters, including the mass of the Higgs boson. The agreement between measurements and expectations from theory is discussed.

Figures (10)

• Figure 1: NuTeV result in the plane of effective right- and left-handed couplings (left) and of on-shell angle versus $\rho$-scale factor $\rho_0$ (right).
• Figure 2: Left: Reconstructed top-quark mass in ${\rm t}\xspace\overline{{\rm t}\xspace}\xspace$ events as measured by CDF. Right: Reconstructed transverse mass in ${\rm W}\xspace$ events as measured by DØ.
• Figure 3: Left: Results on $M_{{\rm W}\xspace}\xspace$ obtained from the TEVATRON and LEP experiments, compared with SM expectations. Right: Contour curve of 68% C.L. in the $(M_{{\rm W}\xspace}\xspace,\Gamma\xspace_{{\rm W}\xspace}\xspace)$ plane. The SM expectation is shown as the arrow for $\Delta\alpha^{(5)}_{had}\xspace=0.02761\pm0.00036$, $M_{{\rm t}\xspace}\xspace=174.3\pm5.1~{\rm Ge V}\xspace$ and $M_{{\rm H}\xspace}\xspace=300^{+700}_{-186}~{\rm Ge V}\xspace$.
• Figure 4: Hadron production in ${\rm e}\xspace^+{\rm e}\xspace^-\xspace$ annihilation.
• Figure 5: Left: Contour curves of 68% C.L. in the $({\rm R}\xspace^{{\rm Z}\xspace}_{\ell\xspace}\xspace,{\rm A}\xspace_{{\rm fb}}\xspace^{0,\ell\xspace}\xspace)$ plane with and without lepton-universality. The SM expectation is shown as the arrows for $M_{{\rm t}\xspace}\xspace=174.3\pm5.1~{\rm Ge V}\xspace$ and $M_{{\rm H}\xspace}\xspace=300^{+700}_{-186}~{\rm Ge V}\xspace$, $\alpha_S\xspace=0.118\pm0.002$, and, shifted for visibility, $\Delta\alpha^{(5)}_{had}\xspace=0.02761\pm0.0036$. Right: Tau polarisation as a function of the polar scattering angle in tau-pair production at LEP-1. The results of a fit to the data, with or without assuming e-$\tau$ universality, are shown as the dashed and solid line.