Determination of the strong coupling constant αs
Year: 2025
Type: article
Abstract: We demonstrate the feasibility of determining the strong coupling constant, α s , from the inclusive semileptonic decay width of B mesons. We express the semileptonic B decay width as a function of α s ( 5 GeV ) , the Cabibbo-Kobayashi-Maskawa matrix element | V c b | , and b - and c -quark masses in the MS ¯ scheme. We fit α s ( 5 GeV ) to current world averages of the B ± and B 0 semileptonic decay widths. This yields α s ( 5 GeV ) = 0.245 ± 0.009 , corresponding to a five-flavor extrapolation of α s ( m Z ) = 0.1266 ± 0.0023 . The primary uncertainty contributions arise from the uncertainty on the perturbative expansion and the value of | V c b | . Future advancements, including higher-order perturbative calculations and precise measurements of | V c b | and B decay widths from upcoming B and Z factories, could enable this method to determine α s ( m Z ) with a competitive precision of Δ α s ( m Z ) ∼ 0.0018 . This precision is comparable to the current accuracy of α s ( m Z ) measurements from τ -lepton decays, which is regarded as the most precise experimental approach.
DOI: 10.5167/uzh-282437
Authors: Che, Yuzhi, Chen, Long, Wu, Jinfei, Lou, Xinchou, Chen, Xiang, Guan, Xin, Ma, Yan-Qing, Ruan, Manqi
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7124744358
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