Abstract
The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. The neutron lifetime recently obtained, 878.5±0.7stat±0.3sys s, is the most accurate one to date. The new result for the neutron lifetime differs from the world average value by 6.5σ. The impact of the new result on testing of Standard Model and on data analysis for the primordial nucleosynthesis model is scrutinized.
Highlights
The problem of precise measurements of the neutron lifetime is important for elementary particle physics and cosmology
In the Standard Model of elementary particles, the quark mixing is described by the Cabibbo–Kobayashi–Maskawa (CKM) matrix which must be unitary
The required relative accuracy of measuring the neutron lifetime τn must be higher than 10-3 and than 2·10-3 for A0
Summary
The main aim of precision measurements of neutron β-decay is to find deviations from the Standard Model assumptions as possible indications of new physics. As far as unitarity test is concerned the following equation can be written: nVud 2 + Vus 2 + Vub 2 = 1.0038(28) , Δ= –1.5σ. In this case the difference nVud – 00Vud = (–1.5±2.0)·10-3 or –1.5σ and the nVud 2 + Vus 2 + Vub 2 =0.9981(28), Δ= +1.7σ. The both differences do not exceed two standard deviations but have opposite sign with respect to previous analysis with new neutron lifetime data. The independent and precise measurements of neutron lifetime are needed as well as checking the result of the experiment [4] in spite of very high methodical level of new experiment
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