In the present work of the PIENU experiment, heavy neutrinos were sought in pion decays π+→μ+ν at rest by examining the observed muon energy spectrum for extra peaks in addition to the expected peak ...for a light neutrino. No evidence for heavy neutrinos was observed. Upper limits were set on the neutrino mixing matrix |Uμi|2 in the neutrino mass region of 15.7–33.8 MeV/c2, improving on previous results by an order of magnitude.
A search for massive neutrinos has been made in the decay π+→e+ν. No evidence was found for extra peaks in the positron energy spectrum indicative of pion decays involving massive neutrinos (π→e+νh). ...Upper limits (90% C.L.) on the neutrino mixing matrix element |Uei|2 in the neutrino mass region 60–135 MeV/c2 were set and are an order of magnitude improvement over previous results.
A new measurement of the branching ratio R_{e/μ}=Γ(π^{+}→e^{+}ν+π^{+}→e^{+}νγ)/Γ(π^{+}→μ^{+}ν+π^{+}→μ^{+}νγ) resulted in R_{e/μ}^{exp}=1.2344±0.0023(stat)±0.0019(syst)×10^{-4}. This is in agreement ...with the standard model prediction and improves the test of electron-muon universality to the level of 0.1%.
The explicit breaking of the axial symmetry by quantum fluctuations gives rise to the so-called axial anomaly. This phenomenon is solely responsible for the decay of the neutral pion π
into two ...photons (γγ), leading to its unusually short lifetime. We precisely measured the decay width Γ of the Formula: see text process. The differential cross sections for π
photoproduction at forward angles were measured on two targets, carbon-12 and silicon-28, yielding Formula: see text, where stat. denotes the statistical uncertainty and syst. the systematic uncertainty. We combined the results of this and an earlier experiment to generate a weighted average of Formula: see text Our final result has a total uncertainty of 1.50% and confirms the prediction based on the chiral anomaly in quantum chromodynamics.
The three body pion decays ... where X is a weakly interacting neutral boson, were searched for using the full data set from the PIENU experiment. An improved limit on ... in the mass range ... and a ...first result for ... in the region ... were obtained. The Majoron-neutrino coupling model was also constrained using the current experimental result of the ... branching ratio.(ProQuest: ... denotes formulae omitted.)
Charged lepton flavor violating muon decay μ+ → e+XH, where XH is a massive neutral boson, was sought by searching for extra peaks in the muon decay μ+ → e+ν¯ν energy spectrum in the mXH mass region ...47.8–95.1 MeV/c2. No signal was found and 90% confidence level upper limits were set on the branching ratio Γ(μ+ → e+XH)/Γ(μ+ → e+ν¯ν) at the level of 10−5 for this region.
PANDA Grid – a Tool for Physics Protopopescu, D; Schwarz, K
Journal of physics. Conference series,
12/2011, Volume:
331, Issue:
7
Journal Article
Peer reviewed
Open access
PANDA Grid is the computing tool of the ANDA experiment at FAIR with concerted efforts dedicated to evolving it beyond passive computing infrastructure, into a complete and transparent solution for ...physics simulation, reconstruction and analysis, a tool right at the fingertips of the physicist. ANDA's position within the larger FAIR community, synergies with other FAIR experiments and with ALICE@LHC, together with recent progress are reported.
The PIENU experiment aims to measure the branching ratio of the charged pion decay with precision of < 0.1 %. This measurement is much sensitive to search for massive neutrinos coupled to electrons ...in
π
+
→
e
+
ν
e
decay. The initial analysis was completed and the upper limit on the neutrino mixing parameter |
U
e
i
|
2
in the neutrino mass range of 0 to 55 MeV/
c
2
was improved by a factor of 1.5, and the sensitivity for the mass range of 68 to 129 MeV/
c
2
was improve by a factor of up to 4.
The pion branching ratio,
R
π
=
Γ
(
π
+
→
e
+
ν
e
+
π
+
→
e
+
ν
e
γ
)
Γ
(
π
+
→
μ
+
ν
μ
+
π
+
→
μ
+
ν
μ
γ
)
, provides a sensitive test of lepton universality and constraints on many new physics ...scenarios. The theoretical uncertainty on the Standard Model prediction of
R
π
is 0.02 %, a factor of twenty smaller than the experimental uncertainty. The analysis of a subset of data taken by the PIENU experiment will be presented. The result,
R
π
= (1.2344 ± 0.0023(
s
t
a
t
) ± 0.0019(
s
y
s
t
)) ⋅ 10
−4
1
, is consistent with the Standard Model prediction and represents a 0.1 % constraint on lepton non-universality.
Status of the PIENU experiment at TRIUMF Ito, S; Aguilar-Arevalo, A; Aoki, M ...
Journal of physics. Conference series,
07/2015, Volume:
631, Issue:
1
Journal Article
Peer reviewed
Open access
The PIENU experiment at TRIUMF aims to measure the branching ratio of pion decays R = Γ(π+ → e+νe + π+ → e+ νeγ) Γ(π+→μ+νμ + π+ → μ+νμγ) with precision <0.1%, providing a stringent test of the ...Standard Model hypothesis of electron-muon universality and a search for new physics.
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