Speaker
Prof.
Kazimierz Bodek
(Uniwersytet Jagiellonski, Instytut Fizyki, Krakow, Poland)
Description
The Standard Model (SM) predictions of T-violation for weak decays of systems built up of u and d quarks are by 7 to 10 orders of magnitude lower than the experimental accuracies attainable at present. It is a general presumption that time reversal phenomena are caused by a tiny admixture of exotic interaction terms. Therefore, weak decays provide a favorable testing ground in a search for such feeble forces. Physics with very slow, polarized neutrons has a great potential in this respect. Our experiment seeks for small deviations from the SM in two observables that have never before been addressed experimentally in free neutron decay. The first of these, the R-correlation coefficient, is proportional to the electron polarization component perpendicular to the plane spanned by the spin of the decaying neutron and the electron momentum. Its non-zero value (corrected for the electromagnetic effects) would signal a violation of time reversal symmetry and thus an existence of physics beyond the Standard Model. The second observable, the N-correlation coefficient, is given by the transverse electron polarization component
within the above mentioned plane. Within the SM its value is significantly different from zero and it scales with the decay asymmetry parameter A. The measurement of N, both, probes the SM and serves as an important systematic check of the experimental apparatus with respect to the R-correlation measurement. The N- and R-correlation coefficients are sensitive to real and imaginary parts of the same linear combination of the scalar and tensor interaction coupling constants, respectively. Experimental determination of the N and R coefficients will help to further constrain possible contributions of these exotic couplings.
The experiment has been carried out on the polarized cold neutron beam facility FUNSPIN of the SINQ spallation source at the Paul Scherrer Institute, Villigen, Switzerland. The transverse polarization of electrons from the neutron decay was analyzed in the Mott scattering from lead nuclei. Data taking has been completed and the analysis is in progress. The newest results will be presented.
A possible future experiment leading to the accuracy improved by at least an order of magnitude will be discussed.
Author
Prof.
Kazimierz Bodek
(Uniwersytet Jagiellonski, Instytut Fizyki, Krakow, Poland)
Co-authors
Dr
Adam Kozela
(Polska Akademia Nauk, Instytut Fizyki Jadrowej, Krakow, Poland)
Dr
Bialek Aleksandra
(Polska Akademia Nauk, Instytut Fizyki Jadrowej, Krakow, Poland)
Dr
Elzbieta Stephan
(Uniwersytet Śląski, Instytut Fizyki, Katowice, Poland)
Prof.
Gilles Ban
(Laboratoire de Physique Corpusculaire, Caen, France)
Dr
Jacek Zejma
(Uniwersytet Jagiellonski, Instytut Fizyki, Krakow, Poland)
Prof.
Klaus Kirch
(Paul Scherrer Institut, Villigen, Switzerland; Federal Institute of Technology, Zurich, Switzerland)
Dr
Marcin Kuzniak
(Uniwersytet Jagiellonski, Instytut Fizyki, Krakow, Poland; Paul Scherrer Institute, Villigen, Switzerland)
Prof.
Nathal Severijns
(Katholieke Universiteit, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium)
Prof.
OSCAR Naviliat-Cuncic
(Laboratoire de Physique Corpusculaire, Caen, France)
Dr
Pierre Gorel
(Laboratoire de Physique Corpusculaire, Caen, France; Paul Scherrer Institute, Villigen, Switzerland)
Dr
Stanislaw Kistryn
(Uniwersytet Jagiellonski, Instytut Fizyki, Krakow, Poland)
