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Measurement of Transverse Polarization of Electrons Emitted in Free Neutron Decay
Kozela A., Ban G., Białek A., Bodek K., Gorel P. et al
Physique/Physique Nucléaire Expérimentale
Measurement of Transverse Polarization of Electrons Emitted in Free Neutron Decay
A. Kozela, G. Ban1, A. Białek, K. Bodek, P. Gorel1, 2, K. Kirch, St. Kistryn, O. Naviliat-Cuncic1, N. Severijns, E. Stephan, J. Zejma
1 :  LPCC - Laboratoire de Physique Corpusculaire de Caen
CNRS : UMR6534 – IN2P3 – Université de Caen Basse-Normandie – Ecole Nationale Supérieure d'Ingénieurs de Caen
ENSICAEN - 6, boulevard du Marechal Juin 14050 Caen Cedex
2 :  PSI - Paul Scherrer Institut
Paul Scherrer Institut, Villigen PSI, CH5232 Villigen, Suisse
Interactions fondamentales
The final analysis of the experiment determining both components of the transverse polarization of electrons ($\sigma_{T_{1}}$, $\sigma_{T_{2}}$) emitted in the $\beta$-decay of polarized, free neutrons is presented. The T-odd, P-odd correlation coefficient quantifying $\sigma_{T_{2}}$, perpendicular to the neutron polarization and electron momentum, was found to be $R=$ 0.004$\pm0.012\pm$0.005. This value is consistent with time reversal invariance, and significantly improves both earlier result and limits on the relative strength of imaginary scalar couplings in the weak interaction. The value obtained for the correlation coefficient associated with $\sigma_{T_{1}}$, $N=$ 0.067$\pm0.011\pm$0.004, agrees with the Standard Model expectation, providing an important sensitivity test of the experimental setup. The present result sets constraints on the imaginary part of scalar and tensor couplings in weak interaction. Implications for parameters of the leptoquark exchange model and minimal supersymmetric model (MSSM) with R-parity violation are discussed.


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