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Title: Global hyperon polarization at local thermodynamic equilibrium with vorticity, magnetic field, and feed-down

Authors:
; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1355964
Grant/Contract Number:
FG02-92ER-40713
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 95; Journal Issue: 5; Related Information: CHORUS Timestamp: 2017-05-05 22:11:17; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Becattini, Francesco, Karpenko, Iurii, Lisa, Michael Annan, Upsal, Isaac, and Voloshin, Sergei A. Global hyperon polarization at local thermodynamic equilibrium with vorticity, magnetic field, and feed-down. United States: N. p., 2017. Web. doi:10.1103/PhysRevC.95.054902.
Becattini, Francesco, Karpenko, Iurii, Lisa, Michael Annan, Upsal, Isaac, & Voloshin, Sergei A. Global hyperon polarization at local thermodynamic equilibrium with vorticity, magnetic field, and feed-down. United States. doi:10.1103/PhysRevC.95.054902.
Becattini, Francesco, Karpenko, Iurii, Lisa, Michael Annan, Upsal, Isaac, and Voloshin, Sergei A. Fri . "Global hyperon polarization at local thermodynamic equilibrium with vorticity, magnetic field, and feed-down". United States. doi:10.1103/PhysRevC.95.054902.
@article{osti_1355964,
title = {Global hyperon polarization at local thermodynamic equilibrium with vorticity, magnetic field, and feed-down},
author = {Becattini, Francesco and Karpenko, Iurii and Lisa, Michael Annan and Upsal, Isaac and Voloshin, Sergei A.},
abstractNote = {},
doi = {10.1103/PhysRevC.95.054902},
journal = {Physical Review C},
number = 5,
volume = 95,
place = {United States},
year = {Fri May 05 00:00:00 EDT 2017},
month = {Fri May 05 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevC.95.054902

Citation Metrics:
Cited by: 19works
Citation information provided by
Web of Science

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  • The extreme energy densities generated by ultra-relativistic collisions between heavy atomic nuclei produce a state of matter that behaves surprisingly like a fluid, with exceptionally high temperature and low viscosity. Non-central collisions have angular momenta of the order of 1,000ћ, and the resulting fluid may have a strong vortical structure that must be understood to describe the fluid properly. The vortical structure is also of particular interest because the restoration of fundamental symmetries of quantum chromodynamics is expected to produce novel physical effects in the presence of strong vorticity. But, no experimental indications of fluid vorticity in heavy ion collisionsmore » have yet been found. Since vorticity represents a local rotational structure of the fluid, spin–orbit coupling can lead to preferential orientation of particle spins along the direction of rotation. Here we present measurements of an alignment between the global angular momentum of a non-central collision and the spin of emitted particles (in this case the collision occurs between gold nuclei and produces Λ baryons), revealing that the fluid produced in heavy ion collisions is the most vortical system so far observed. (At high energies, this fluid is a quark–gluon plasma.) We find that Λ and hyperons show a positive polarization of the order of a few per cent, consistent with some hydrodynamic predictions. (A hyperon is a particle composed of three quarks, at least one of which is a strange quark; the remainder are up and down quarks, found in protons and neutrons.) A previous measurement that reported a null result, that is, zero polarization, at higher collision energies is seen to be consistent with the trend of our observations, though with larger statistical uncertainties. Furthermore, these data provide experimental access to the vortical structure of the nearly ideal liquid created in a heavy ion collision and should prove valuable in the development of hydrodynamic models that quantitatively connect observations to the theory of the strong force.« less
    Cited by 8
  • We demonstrate that a purely ideal mechanism, originating in the space-time distortion caused by the demands of special relativity, can break the topological constraint (leading to helicity conservation) that would forbid the emergence of a magnetic field (a generalized vorticity) in an ideal nonrelativistic dynamics. The new mechanism, arising from the interaction between the inhomogeneous flow fields and inhomogeneous entropy, is universal and can provide a finite seed even for mildly relativistic flows.