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Equation 9 · Part 2 · How Particle Physics Beyond the Standard Model Actually Works

Symbol K

R(K)R(K)
KK

What this part means

K is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

K is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

Resolved: the LHCb lepton-universality ratios. Measurements of R(K) and R(K∗K^{*}) — ratios comparing B -meson decays to muon pairs versus electron pairs, which the Standard Model predicts should be equal — showed apparent deviations through 2021 that fueled substantial theoretical interest in new mediator particles. LHCb’s December 2022 reanalysis, using the full Run 1 and Run 2 dataset with improved control of electron-misidentification backgrounds, found both ratios consistent with the Standard Model at the one-standard-deviation level. LHCb spokesperson Chris Parkes attributed the earlier apparent deviation to systematic effects in background modeling, not a statistical fluctuation in the…

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A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the surrounding passage

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