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I. P. Yudin

Publications and source records attributed to I. P. Yudin.

3 recordsLinked to original sources

Right sign of spin rotation operator

For the fermion transformation in the space all books of quantum mechanics propose to use the unitary operator $\widehat{U}_{\vec n}(φ)=\exp{(-i\frac\varphi2(\widehatσ\cdot\vec n))}$, where $φ$ is angle of rotation around the axis $\vec{n}$. But this operator turns the spin in inverse direction presenting the rotation to the left. The error of defining of $\widehat{U}_{\vec n}(φ)$ action is caused because the spin supposed as simple vector which is independent from $\widehatσ$-operator a priori. In this work it is shown that each fermion marked by number $i$ has own Pauli-vector $\widehatσ_i$ and both of them change together. If we suppose the global $\widehatσ$-operator and using the Bloch Sphere approach define for all fermions the common quantization axis $z$ the spin transformation will be the same: the right hand rotation around the axis $\vec{n}$ is performed by the operator $\widehat{U}^+_{\vec n}(φ)=\exp{(+i\frac\varphi2(\widehatσ\cdot\vec n))}$.

quant-ph

Charge-exchange quasi-elastic process $nd\to p(nn)$ under $0^\circ$ in the frame of elastic $np\to np$ scattering to $180^\circ$

It is considered the problem of spin physics related with the difference of representation of the elastic interaction between the neutron and proton. In the first case the charge-exchange reaction $np\to pn$ under the angle $θ$ is supposed, in the second --- the simple elastic scattering of $np\to np$, when the neutron is going in opposite direction $π-θ$. The transition from one representation to another is provided by the Majorana operator. In the framework of impulse approximation it is twice calculated the quasi-elastic charge-exchange reaction of a neutron on a deuteron. In the frame of $nd\to p(nn)$ scattering of proton to the angle $θ$ it gives the well-known Dean formula. Using other representation $nd\to (nn)p$ as a neutron elastic scattering under the angle $π-θ$ (together with neutron-spectator in $nn$-pair) the alternative formula is presented.

nucl-th

Interesting effect of the nd -> p(nn) reaction

The reaction nd -> p(nn) produce two slow neutrons in the final state instead of deuteron. In the first view we can take into account the binding energy e ~ 2.23 MeV but this approach can not explain all features which are observed in the momentum spectrum of the secondaries protons. We need to suppose that two slow neutrons in the final state form the intermediate system which has own distribution of internal Fermi momentum.

nucl-th