Conveners
Strangeness (Global Polarization): Parallel 4
- Isaac Upsal (SDU/BNL)
The system created in relativistic nucleus-nucleus collisions may possess large orbital angular momentum leading to the global polarization of particles perpendicular to the reaction plane. The local asymmetries in the velocity fields due to anisotropic flow can also generate vorticity and particle polarization along the beam direction. In parity-violating weak decays of hyperons, the momentum...
The physics interpretation of the recent measurements of the spin polarization of Λ hyperons produced in relativistic heavy-ion collisions is discussed. We suggest that the polarization measured in the Λ rest frame should be projected along the direction of the total angular momentum that is first transformed to the same frame, and only then averaged over Λ's with different momenta in the...
Non-central heavy-ion collisions produce a large angular momentum that leads to vorticity of the created system. Due to the spin-orbit coupling, spin directions
of particles are aligned with the orbital angular momentum of the system. Global
polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons has been measured in Au+Au collisions from $\sqrt{s_{\rm{NN}}}$ = 7.7 GeV to 200 GeV[1][2]. The...
In a non-central nucleus-nucleus collision, the colliding system carries large orbital angular momentum, part of which remains within the hot dense matter created by the collision. This angular momentum turns into complex fluid vorticity structures in the rapidly expanding bulk fluid and eventually manifests itself through the global spin polarization of produced particles such as hyperons....
In non-central heavy-ion collisions the orbital angular momentum can reach high values up $10^4\hbar$. This might lead to a global spin polarization of the particles being produced. The STAR results, as measured during the beam energy scan phase I, show an enhancement of the global polarization towards lower beam energies. At a collision energy of $\sqrt{s_{NN}} = 7.7\,$GeV a polarization of a...
