Measurement of the transverse polarization of electrons emitted in neutron decay – nTRV experiment

This paper recalls the main achievements of the nTRV experiment which measured two components of the transverse polarization (\sigma_{T_{1}}σT1, \sigma_{T_{2}}σT2) of electrons emitted in the \betaβ-decay of polarized, free neutrons and deduced two correlation coefficients, RR and NN, that are sensitive to physics beyond the Standard Model. The value of time-reversal odd coefficient RR, 0.004\pm±0.012\pm±0.005, significantly improved limits on the relative strength of imaginary scalar coupling constant in the weak interaction. The value obtained for the time-reversal even correlation coefficient NN, 0.067\pm±0.011\pm±0.004, agrees with the Standard Model expectation, providing an important sensitivity test of the electron polarimeter. One of the conclusions of this pioneering experiment was that the transverse electron polarization in the neutron \betaβ-decay is worth more systematic exploring by measurements of yet experimentally not attempted correlation coefficients such as HH, LL, SS, UU and VV. This article presents a brief outlook on that questions.

TWO-CENTER PROBLEM FOR THE DIRAC EQUATION WITH A COULOMB AND SCALAR POTENTIAL

The ground state wave function and the energy term of a relativistic electron moving in the field of two fixed centers, when interaction of this particle with centers is described by two Coulomb and two Coulomb-like scalar potentials are calculated analytically by the LCAO method. Dependence of electron binding energy from value of scalar coupling constant was investigated using obtained analytic results.

NUCLEAR EQUATION OF STATE IN THE MODIFIED CHIRAL SIGMA MODEL

We have developed a modified chiral sigma model by expressing the scalar and the vector vertices in terms of the positive- and negative-energy projection operators with two additional free parameters. The scalar and the vector coupling constants depend on the density of our model. We find that at densities higher than that of the saturation, the energy per particle decreases as the scalar coupling constant becomes stronger. In this model, the values of incompressibility and effective nucleon mass at the saturation density are sensitive to the strength of the scalar coupling constant. We find that the modified chiral sigma model can overcome the most of the shortcomings of the chiral sigma model and reproduce values of incompressibility, nucleon effective mass and coupling constants at the saturation density in the acceptable range.