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preprints:2004:ttp04-13 [2016/03/17 11:03] (current)
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 +====== TTP04-13 Precision Measurements and CKM Unitarity ====== 
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 +   <​hidden TTP04-13 ​ Precision Measurements and CKM Unitarity > Determinations of |Vud| and |Vus| along with their implications for the 
 + ​unitarity test |Vud|^2+|Vus|^2+|Vub|^2=1 are discussed. The leading two loop 
 + ​radiative corrections to neutron beta-decay are evaluated and used to derive a 
 + ​refined relationship |Vud|^2 tau_n (1+3g_A^2)=4908(4)sec. Employing |Vud| 
 + ​=0.9740(5) from superallowed nuclear decays and the measured neutron lifetime, 
 + tau_n = 885.7(7)sec leads to the precise prediction g_A=1.2703(8) which is 
 + ​compared with current direct experimental values. Various extractions of |Vus| 
 + are described and updated. The long accepted Particle Data Group value of |Vus| 
 + from fitted K_{e3} decay rates suggests a deviation from CKM unitarity but it 
 + is contradicted by more recent experimental results which confirm unitarity 
 + with good precision. An outlook for possible future advances is given. 
 + </​hidden>​ 
 +|**Andrzej Czarnecki, William J. Marciano, Alberto Sirlin** ​ |  
 +|**  Phys.Rev. ​ D70 093006 2004  **  | 
 +| {{preprints:​2004:​ttp04-13.pdf|PDF}} {{preprints:​2004:​ttp04-13.ps|PostScript}} [[http://​arxiv.org/​abs/​hep-ph/​0406324|arXiv]] ​  | 
 +| |