Spin alignment of K∗(892)±K^*(892)^\pm mesons produced in neutron-carbon interactions

A new precise measurements of spin density matrix element $\rho_{00}$ of $K^*(892)^{\pm}$ mesons produced inclusively in neutron-carbon interactions at \~60 GeV have been carried out in the EXCHARM experiment at the Serpukhov accelerator. The values of $\rho_{00}$ obtained in the transversity frame are $0.424\pm0.011(stat)\pm0.018(sys)$ for $K^*(892)^+$ and $0.393\pm0.025(stat)\pm0.018(sys)$ for $K^*(892)^-$. Significant $P_T$ dependence of $\rho_{00}$ has been observed in $K^*(892)^+$ production.Comment: 8 pages, LaTeX, 3 eps figure

Spin alignments of vector mesons in deeply inelastic lepton-nucleon scattering

We extend the calculations of the spin alignments of vector mesons in $e^+e^-$ annihilation in a recent Rapid Communication to deeply inelastic lepton-nucleon scatterings. We present the results for different mesons in the current fragmentation regions of $\mu^- N$$\to$$\mu^- VX$ at high energies and $\nu_\mu N$$\to$$\mu^- VX$ at both high and low energies. We also present the predictions for $\nu_\mu N$$\to$$\mu^- VX$ at NOMAD energies in the target fragmentation region using a valence quark model.Comment: 4 pages, 6 figures; to appear in Phys. Rev.

Polarization phenomena in open charm photoproduction processes

We analyze polarization effects in associative photoproduction of pseudoscalar ($\bar{D}$) charmed mesons in exclusive processes $\gamma+ N\to Y_c +\bar{D}$, $Y_c=\Lambda_c^+$, $\Sigma_c$. Circularly polarized photons induce nonzero polarization of the $Y_c$-hyperon with $x$- and $z$-components (in the reaction plane) and non vanishing asymmetries ${\cal A}_x$ and ${\cal A}_z$ for polarized nucleon target. These polarization observables can be predicted in model-independent way for exclusive $\bar{D}$-production processes in collinear kinematics. The T-even $Y_c$-polarization and asymmetries for non-collinear kinematics can be calculated in framework of an effective Lagrangian approach. The depolarization coefficients $D_{ab}$, characterizing the dependence of the $Y_c$-polarization on the nucleon polarization are also calculated.Comment: 36 pages 13 figure

A-dependence of phi-meson production in p+A collisions

A systematic analysis of the A-dependence of phi-meson production in proton-nucleus collisions is presented. We apply different formalisms for the evaluation of the phi-meson distortion in nuclei and discuss the theoretical uncertainties of the data analysis. The corresponding results are compared to theoretical predictions. We also discuss the interpretation of the extracted results with respect to different observables and provide relations between frequently used definitions. The perspectives of future experiments are evaluated and estimates based on our systematical study are given.Comment: 14 pages, 8 figure

Search for asymmetry in decays of charmed baryons c)

Translated from Russian. Published in Rapid Communications JINR--1-84, p. 13-17Available from Deutsches Elektronen-Synchrotron (DESY), Hamburg (DE) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman