Global Λ polarization in high energy collisions

Abstract

With a Yang-Mills flux-tube initial state and a high-resolution (3+1)D particle-in-cell relativistic (PICR) hydrodynamics simulation, we calculate the polarization for different energies. The origination of polarization in high energy collisions is discussed, and we find linear impact parameter dependence of the global polarization. Furthermore, the global polarization in our model decreases very quickly in the low energy domain, and the decline curve fits well the recent results of Beam Energy Scan (BES) program launched by the STAR Collaboration at the Relativistic Heavy Ion Collider (RHIC). The time evolution of polarization is also discussed.

Collective Longitudinal Polarization in Relativistic Heavy-Ion Collisions at Very High Energy

“…This finding confirms early proposals [3,4], later predictions based on local thermodynamic equilibrium of spin degrees of freedom [5,6] which provides a relation between polarization and relativistic vorticity, and it agrees quantitatively with the hydrodynamic model calculations [7][8][9] to a very good degree of accuracy. In the hydrodynamic framework, the distinctive feature of polarization is its proportionality to the gradients of the combined temperature and velocity fields (see eq.…”

“…GeV to few permille at √ s NN = O(100) GeV, in agreement with calculations based on the hydrodynamic model [8][9][10] as well with hybrid approaches [11,12]. In the TeV energy range, at the LHC, the global polarization along J is not seen [13] as it is most likely beyond experimental sensitivity.…”

Study of Lambda polarization at RHIC BES and LHC energies

“…The magnitude of measured polarization is in general agreement with calculations from different hydrodynamic models [2,3] and AMPT [4,5]. In the hydrodynamic models the Λ hyperons produced at particlization (fluid to particle transition) hypersurface acquire polarization via spin-vorticity coupling mechanism.…”

Non-mesonic decay of the η-mesic 3He via pd→(3Skurzok1, Hirenzaki2, Kinutani3 et al. 2020Nuclear Physics A9010View full textAdd to dashboardCite

“…They are currently one of the hottest topics in nuclear and hadronic physics, both from experimental [7,8,9,10,11,12] and theoretical [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34] standpoints. Some of the most promising candidates for such bound states are η(η )-mesic nuclei since the η-nucleon interaction was found to be attractive [35,36] while the imaginary η -nucleus potential for near threshold is significantly smaller than the modulus of the real part [37].…”

“…Recently performed studies of hadron-and photo-production of the η meson result in a wide range of values of the ηN scattering length indicating that the η meson-nucleon interaction is attractive and strong enough to create even light η-nucleus bound systems [15,16,17,18,19,38,39,40]. However, none of the experiments performed till now have found a clear signature confirming their existence.…”