Measurement of the energy spectrum of νe from muon decay and implications for the Lorentz structure of the weak interaction
KARMEN group, B. Armbruster, I. M. Blair, B. A. Bodmann, N. E. Booth, G. Drexlin, V. Eberhard, J. A. Edgington, C. Eichner, K. Eitel, E. Finckh, H. Gemmeke, J. Hößl, T. Jannakos, P. Jünger, M. Kleifges, J. Kleinfeller, W. Kretschmer, R. Maschuw, C. Oehler, P. Plischke, J. Rapp, C. Ruf, M. Steidl, O. Stumm, J. Wolf, B. Zeitnitz
Abstract
The KARMEN experiment uses the reaction 12C(νe,e-)12N to measure the energy distribution of νe emitted in muon decay at rest. The νe analog ωl of the famous Michel parameter ρhas been derived from a maximum-likelihood analysis of events near the kinematic end point, Emax. The result, ωl = (2.7+3.8-3.3 3.1) * 10-2, is in good agreement with the standard model prediction ωl= 0. We deduce a 90% confidence upper limit of ωl <= 0.113, which corresponds to a limit of |gSRL + 2 gTRL| <= 0.78 on the interference term between scalar and tensor coupling constants.
Create a lesson
Related papers
Observation of double ss production in e+e- collision at s = 3.08~GeV
BESIII Collaboration, M. Ablikim, M. N. Achasov et al.
A heterogeneous and vectorized sequence for the HL-LHC full tracking reconstruction of the CMS experiment
Emmanouil Vourliotis
Coverage Is Not Ordering: Ancillary Leakage and Representation Dependence in Covariance-Based Inference
Tommaso Dorigo
IRIS-HEP 2026 Statistical Ecosystem Blueprint White Paper
Matthew Feickert, Massimiliano Galli
Constraints on the Higgs boson total width from on-shell signal-background interference in the Hγγ decay channel with pp collisions at s=13 TeV with the ATLAS detector
ATLAS Collaboration
Status and Prospects of the HEP Statistical Inference Ecosystem
Massimiliano Galli