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

TL;DR

This paper reports precise measurements of the spin alignment parameter $ ho_{00}$ for $K^*(892)^\pm$ mesons produced in neutron-carbon interactions at 60 GeV, revealing a significant transverse momentum dependence for $K^*(892)^+$.

Contribution

It provides new high-precision data on the spin density matrix element $ ho_{00}$ for $K^*(892)^\pm$ mesons, including the first observation of $P_T$ dependence in $K^*(892)^+$ production.

Findings

Measured $ ho_{00}$ values for $K^*(892)^+$ and $K^*(892)^-$ with high precision.

Observed significant $P_T$ dependence of $ ho_{00}$ for $K^*(892)^+$.

First evidence of $P_T$ dependence in $K^*(892)^+$ spin alignment.

Abstract

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.