Updated results from PIBETA and overview of the PEN experiment

D., Počanić,; M., Bychkov,; VanDevender, B. A.; Alonzi, L. P.; Baranov, V. A.; Bertl, W.; Bystritsky, Yu. M.; Frlež, E.; Khomutov, N. V.; Korenchenko, A. S.; Korenchenko, S.M.; Korolija, M.; Kozlowski, T.; Kravchuk, N. P.; Kuchinsky, N.A.; Mekterović, D.; Mzhavia, D.; Palladino, A.; Robmann, P.; Rozhdestvensky, A.M.; Straumann, U.; Supek, I.; Truöl, P.; Schaaf, A. van der; Velicheva, E. P.; P., Volnykh, V.

doi:10.22323/1.086.0009

Cited by 4 publications

(9 citation statements)

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“…The branching ratio of radiative muon decays was measured long ago for a minimum photon energy ω 0 = 10 MeV in the µ rest frame [16], and more recently by the MEG collaboration for Both measurements agree with our theoretical predictions (see table 1). New precise results are expected from the MEG [6] and PIBETA [17] collaborations. The relative magnitude of radiative corrections were also studied in the specific final-state configuration of the decays (2.1,2.2) when the neutrino energies (E ν and Eν ) are very small, i.e.…”

Section: Radiative µ and τ Leptonic Decays: Branching Ratiosmentioning

confidence: 99%

“…Both measurements agree with our theoretical predictions (see table 1). New precise results are expected from the MEG [6] and PIBETA [17] collaborations.…”

Section: Radiative µ and τ Leptonic Decays: Branching Ratiosmentioning

confidence: 99%

“…These measurements, with a relative error of about 3%, must be compared with the SM predictions of the branching fractions at nextto-leading order (NLO). Indeed these radiative corrections, recently computed in [12], are not protected from mass singularities by the Kinoshita-Lee-Nauenberg (KLN) theorem [13,14,15] and are of relative order (α/π) ln(m l /m τ ) ln(ω 0 /m τ ), corresponding to a large 10% correction for l = e, and 3% for l = µ. Radiative muon decays were measured long ago in [16], and new results were presented recently by the MEG [6] and PIBETA [17] collaborations.…”

Section: Introductionmentioning

confidence: 99%

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Precision tests via radiative $μ$ and $τ$ leptonic decays

Fael

Passera

2016

Proceedings of 12th International Symposium on Radiative Corrections (Radcor 2015) and LoopFest XIV (Radiative Corrections for

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The branching fractions of radiative leptonic τ decays (τ → lννγ, l = e, µ) were recently measured by the BABAR collaboration with a relative error of about 3%. The measurement of the branching ratio B(τ → eννγ), for a minimum photon energy of 10 MeV in the τ rest frame, differs from our recent SM prediction by 3.5 standard deviations, whereas our result agrees with BABAR's value for B(τ → µννγ). Our predictions also agree with the measurement of B(µ → eννγ) by the MEG collaboration. We also report on a recent proposal to test the τ dipole moments via precise measurements of radiative leptonic τ decays at high-luminosity B factories. 12th International Symposium on Radiative Corrections (Radcor 2015) and LoopFest XIV (Radiative Corrections for the LHC and Future Colliders)

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Section: Radiative µ and τ Leptonic Decays: Branching Ratiosmentioning

confidence: 99%

“…Both measurements agree with our theoretical predictions (see table 1). New precise results are expected from the MEG [6] and PIBETA [17] collaborations.…”

Section: Radiative µ and τ Leptonic Decays: Branching Ratiosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Precision tests via radiative $μ$ and $τ$ leptonic decays

Fael

Passera

2016

Proceedings of 12th International Symposium on Radiative Corrections (Radcor 2015) and LoopFest XIV (Radiative Corrections for

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“…The PDG average value is R π exp e/μ = 1.230(4) × 10 −4 (38), which includes results from Reference 46; earlier measurements can be found in References 47-50. Two new experiments under way at TRIUMF (51) and PSI (52) aim to improve the precision of R π exp e/μ by a factor of five or more, thereby challenging the SM prediction to better than ± 0.1%. At that level, New Physics effects could appear as a deviation from expectations.…”

Section: Precision Measurement Of the Rare Leptonic Decay Modes π + → E + ν And K + → E + νmentioning

confidence: 99%

Rare Kaon and Pion Decays: Incisive Probes for New Physics Beyond the Standard Model

Bryman

Marciano

Tschirhart

et al. 2011

Annu. Rev. Nucl. Part. Sci.

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We review the current status and future prospects of rare kaon and pion decay research programs. Our emphasis is on experimental probes of New Physics beyond the Standard Model via the theoretically pristine K → πνν decays and precision tests of electron-muon universality. These studies test the Standard Model at the level of its quantum-loop predictions and have the potential to uncover new interactions beyond the O(1,000 TeV) scale.

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“…The detector optimized for a next-generation R e/µ experiment will also be ideally suited for a high-precision measurement of pion beta decay, which allows one to extract |V ud | in a theoretically pristine manner. The branching ratio for pion beta decay was most accurately measured by the PiBeta experiment at PSI [43][44][45][46][47] to be…”

Section: Motivationmentioning

confidence: 99%

Testing Lepton Flavor Universality and CKM Unitarity with Rare Pion Decays in the PIONEER experiment

Collaboration¹,

Altmannshofer²,

Binney³

et al. 2022

Preprint

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The physics motivation and the conceptual design of the PIONEER experiment, a next-generation rare pion decay experiment testing lepton flavor universality and CKM unitarity, are described. Phase I of the PIONEER experiment, which was proposed and approved at Paul Scherrer Institut, aims at measuring the charged-pion branching ratio to electrons vs. muons, R e/µ , 15 times more precisely than the current experimental result, reaching the precision of the Standard Model (SM) prediction at 1 part in 10 4 . Considering several inconsistencies between the SM predictions and data pointing towards the potential violation of lepton flavor universality, the PIONEER experiment will probe non-SM explanations of these anomalies through sensitivity to quantum effects of new particles up to the PeV mass scale. The later phases of the PIONEER experiment aim at improving the experimental precision of the branching ratio of pion beta decay (BRPB), π + → π 0 e + ν(γ), currently at 1.036(6) × 10 −8 , by a factor of three (Phase II) and an order of magnitude (Phase III). Such precise measurements of BRPB will allow for tests of CKM unitarity in light of the Cabibbo Angle Anomaly and the theoretically cleanest extraction of |V ud | at the 0.02% level, comparable to the deduction from superallowed beta decays.

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Updated results from PIBETA and overview of the PEN experiment

Cited by 4 publications

References 2 publications

Precision tests via radiative $μ$ and $τ$ leptonic decays

Precision tests via radiative $μ$ and $τ$ leptonic decays

Rare Kaon and Pion Decays: Incisive Probes for New Physics Beyond the Standard Model

Testing Lepton Flavor Universality and CKM Unitarity with Rare Pion Decays in the PIONEER experiment

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