Rare pion decays at PIONEER
Dr. Saúl Cuen Rochín,
Escuela de Ingeniería y Ciencias, ITESM, Sinaloa
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, Re/mu, 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. In addition, various exotic rare
decays involving sterile neutrinos and axions will be searched for with
unprecedented sensitivity. The later phases of the PIONEER experiment aim
at improving the experimental precision of the branching ratio of pion
beta decay (BRPB), pi+ -> pi0 e+ nu (gamma), 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.Refs. [1][2]
[1] (Collaboration Proposal), "Testing Lepton Flavor Universality and CKM
Unitarity with Rare Pion Decays in the PIONEER experiment", FERMILAB,
FERMILAB-CONF-22-328-PPD, 2021 Snowmass Summer Study, Seattle, WA, United
States, March 2022, https://cds.cern.ch/record/2806788 [cds.cern.ch]
[2] (Collaboration Proposal), "PIONEER: Studies of Rare Pion Decays\u201d,
CERN, March 2022, https://cds.cern.ch/record/2824583 [cds.cern.ch]
Liga de Zoom:
https://cuaieed-unam.zoom.us/j/82622280628?pwd=c1R1UWpjbDdtM0RwYTNkK09kdmthdz09