Pion electronic decay and lepton universality
Keyword(s):
In common with a number of simple processes involving elementary particles, charged pion decays are profoundly shaped by applicable Standard Model (SM) symmetries and properties. Given the highly precise SM theoretical description, pion decays are used as selective probes of SM parameters, and of possible SM extensions. The PEN experiment at PSI is studying the \pi^+ \to e^+\nu_e(\gamma)π+→e+νe(γ), or \pi_{e2(\gamma)}πe2(γ) decay. The primary goal is to reach the relative precision of 5 \times 10^{-4}5×10−4 in R_{e/\mu}^\piRe/μπ, the branching ratio for \pi_{e2(\gamma)}πe2(γ) decay. We review the PEN research program, its present status, and prospects.
2006 ◽
Vol 21
(27)
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pp. 5652-5659
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2004 ◽
Vol 19
(35)
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pp. 2595-2610
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2007 ◽
Vol 22
(10)
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pp. 1781-1795
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2018 ◽
Vol 33
(32)
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pp. 1850194
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2018 ◽
Vol 4
(2)
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pp. 42