Fig. 2: The reduced asymmetry \({{\boldsymbol{A}}}_{{\bf{ep}}}/{{\boldsymbol{A}}}_{{\bf{0}}}={{\boldsymbol{Q}}}_{{\bf{w}}}^{{\bf{p}}}+{{\boldsymbol{Q}}}^{{\bf{2}}}{\boldsymbol{B}}\left({{\boldsymbol{Q}}}^{{\bf{2}}},{\boldsymbol{\theta }}{\bf{= 0}}\right)\) versus Q2. | Nature

Fig. 2: The reduced asymmetry \({{\boldsymbol{A}}}_{{\bf{ep}}}/{{\boldsymbol{A}}}_{{\bf{0}}}={{\boldsymbol{Q}}}_{{\bf{w}}}^{{\bf{p}}}+{{\boldsymbol{Q}}}^{{\bf{2}}}{\boldsymbol{B}}\left({{\boldsymbol{Q}}}^{{\bf{2}}},{\boldsymbol{\theta }}{\bf{= 0}}\right)\) versus Q2.

From: Precision measurement of the weak charge of the proton

Fig. 2

The global fit is illustrated using ep asymmetries from this experiment (Qweak 2018), from the commissioning phase of this experiment3 (Qweak 2013), as well as from the earlier experiments HAPPEX, SAMPLE, PVA4 and G0 (see Methods), projected to θ = 0° and reduced by a factor A0(Q2) appropriate for each datum. The data shown here include the γZ-box radiative correction and uncertainty. Inner error bars correspond to one standard deviation (s.d.) and include statistical and systematic uncertainties. Outer error bars on the data indicate the additional uncertainty estimated from the forward-angle projection (for some data points, inner and outer error bars coincide). The solid line represents the global fit to the complete PVES database (see Methods), and the yellow band indicates the fit uncertainty (1 s.d.). The arrowhead at Q2 = 0 indicates the standard-model prediction2, \({Q}_{{\rm{w}}}^{{\rm{p}}}=0.0708(3)\), which agrees well with the intercept of the fit (\({Q}_{{\rm{w}}}^{{\rm{p}}}=0.0719\pm 0.0045\)). The inset shows a magnification of the region around this experiment’s result, at \(\langle {Q}^{2}\rangle =0.0248\,{{\rm{G}}{\rm{e}}{\rm{V}}}^{2}\,{c}^{-2}\).

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