The Z ->anti-b b decay asymmetry: lose-lose for the Standard Model

TL;DR

Combining precision measurements and the Higgs boson search limit, the electroweak data have evolved to a point where new physics is favored whether the 3.2 sigma A(b)(FB) anomaly is genuine or not.

Abstract

Combining precision measurements and the Higgs boson search limit, the electroweak data has evolved to a point where new physics is favored whether the 3.2 sigma A_{FB}^b anomaly is genuine or not. Such new physics could greatly alter the inferred value of the Higgs boson mass.

Figures (2)

• Figure 1: $\chi^2$ distributions as a function of $m_H$. The solid line is obtained from $m_W$ alone and the dashed line from the combined fit of $m_W$, $\Gamma_Z$, and $R_l$. The vertical dotted line indicates the direct search lower limit and the horizontal dotted line indicates the value of $\Delta \chi^2$ corresponding to a 95% CL upper limit. $\alpha(m_Z)$ is from bp.
• Figure 2: $\chi^2$ distributions as in figure 1. The lines correspond to fits of $m_W$, $\Gamma_Z$, and $R_l$, combined incrementally, as in table 2, with the four leptonic asymmetry measurements (solid), plus $Q_{FB}$ (dashes), plus $A_{FB}^c$ (dot-dashes), plus $A_{FB}^b$ (dots).