6 research outputs found
The spin alignment of vector mesons with light front quarks
The global spin alignment of the vector meson has been observed in
relativistic heavy ion collisions, but is still on hot debates in the
theoretical community. Here we propose to apply the light front framework to
explain this phenomenon since the light front form explicitly describes the
hadron spin including both the quark spin and the orbital angular momentum.
After applying the light front spinor, we find that the spin alignment in the
polarization of vector mesons with can be naturally manifested
and in particular, the obtained spin alignment for meson is in good
agreement with the experimental data. This implies that to explain the spin
alignment it is important to properly include the contribution from the gluon
interactions that are presented in terms of the orbital angular momentum of the
hadron bound state.Comment: 7 pages, 2 figure
Collective flow and the fluid behavior in p/d/He+Au collisions at GeV
By varying the intrinsic initial geometry, the p/d/He+Au collisions at
the Relativistic Heavy Ion Collider (RHIC) provide a unique opportunity to
understand the collective behavior in the small systems. In this paper, we
employ the hybrid model iEBE-VISHNU with TRENTO initial conditions to study the
collective flow and the fluid behavior in p/d/He+Au collisions. With
fine-tuned parameters, iEBE-VISHNU can describe the and
data from the PHENIX and STAR collaborations. However, for these parameter sets
tuned to fit the STAR data, the hydrodynamic simulations have already beyond
their limits with the average Knudsen number obviously
larger than one. Our calculations demonstrate that, for a meaningful evaluation
of the fluid behavior in the small systems, model simulations should also pay
attention to the validity range of hydrodynamics
Shear-induced spin polarization and “strange memory” in heavy-ion collisions
We discuss the theory of the spin polarizations induced by hydrodynamic gradients, which includes a newly discovered shear-induced polarization (SIP) term. In the phenomenological study using a hydrodynamic model, we discover that the local polarization contributed by SIP is substantial and has the “same sign” as the experimental measurements. Also, we find that the “sign” property of the local polarization observed in experiments seems to be related to “memory” effects on the polarizations of strange quarks in quark-gluon plasma