Fluid dynamics study of the $$\varLambda $$ polarization for Au + Au collisions at $$\sqrt{s_{NN}}=200$$ GeV

Xie, Y.; Wang, Dujuan; Csernai, L. P.

doi:10.1140/epjc/s10052-019-7576-8

Cited by 32 publications

(18 citation statements)

References 33 publications

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“…(15), as compared to Eq. (14) of Ref. [20], compensate this reduction and contribute significantly to a higher interaction rate.…”

Section: Resultsmentioning

confidence: 99%

“…Notice that Eq. (14) implies that the available phase space is reduced in the massive quark case, as one could expect. The polarization coefficients C L;T come from the contraction of the polarization tensors P L;Tμν with the trace of the factors involving Dirac gamma matrices from the self-energy.…”

Section: Quark Interaction Rate At Finite Density and Temperaturementioning

confidence: 87%

“…Were this to be the case, the most promising way to elucidate its properties is by means of the alignment of particle spin to the global angular momentum, which in turn could be detected measuring a nonvanishing global particle polarization. This possibility has prompted the search for global polarization of hadrons, most notably of Λ andΛ [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The STAR Beam Energy Scan (BES) program has measured the Λ andΛ global polarizations as functions of the collision energy [17][18][19] showing that as the latter decreases, theΛ polarization rises more steeply than the Λ polarization.…”

Section: Introductionmentioning

confidence: 99%

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Relaxation time for the alignment between the spin of a finite-mass quark or antiquark and the thermal vorticity in relativistic heavy-ion collisions

et al. 2020

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We study the relaxation time required for the alignment between the spin of a finite-mass quark or antiquark and the thermal vorticity, at finite temperature and baryon chemical potential, in the context of relativistic heavy-ion collisions. The relaxation time is computed as the inverse of the total reaction rate that in turn is obtained from the imaginary part of the quark or antiquark self-energy. We model the interaction between spin and thermal vorticity within the medium by means of a vertex coupling quarks and thermal gluons that, for a uniform temperature, is proportional to the global angular velocity and inversely proportional to the temperature. We use realistic estimates for the angular velocities for different collision energies and show that the effect of the quark mass is to reduce the relaxation times as compared to the massless quark case. Using these relaxation times we estimate the intrinsic quark and antiquark polarizations produced by the thermal vorticity. We conclude by pointing out that, although the intrinsic global polarization of the s-quark turns out to be larger than that of thes-quark, there is room to explain recent STAR results which show that the global polarization ofΛ is larger than that of Λ when considering that these hyperons can be produced from different density regions in a core-corona model.

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“…(15), as compared to Eq. (14) of Ref. [20], compensate this reduction and contribute significantly to a higher interaction rate.…”

Section: Resultsmentioning

confidence: 99%

Section: Quark Interaction Rate At Finite Density and Temperaturementioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Relaxation time for the alignment between the spin of a finite-mass quark or antiquark and the thermal vorticity in relativistic heavy-ion collisions

et al. 2020

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“…Locally, the longitudinal polarization on transverse momentum plane, from model simulations of both a multiple phase transport (AMPT) model [18] and the hydrodynamic model [19,20], exhibits opposite signature to the experimentally observed quadrupolar structure [21]. Many recent works have been devoted to this problem [22][23][24], and the feed-down effect from hyperon decay was proved to be too trivial to explain [25,26].Our recent work [27] using the high resolution (3+1)D Particle-In-Cell Relativistic (PICR) hydrodynamic model to calculate the polarization at 200 GeV Au-Au, shows a fairly good agreement to the experimentally observed longitudinal polarization.…”

Section: Introductionmentioning

confidence: 99%

A study of $$\varLambda $$ and $$\bar{\varLambda }$$ polarization splitting by meson field in PICR hydrodynamic model

2021

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With the PICR hydrodynamic model, we study the polarization splitting between $$\varLambda $$ Λ and $$\bar{\varLambda }$$ Λ ¯ at RHIC BES energy range, based on the meson field mechanism. Our results fit to the experimental data fairly well. Besides, two unexpected effect emerges: (1) the baryon density gradient has non-trivial and negative contribution to the polarization splitting; (2) for 7.7 GeV Au+Au collisions within the centrality range of 20–50%, the polarization splitting surprisingly increases with the centrality decreases. The second effect might help to explain the significant signal of polarization splitting measured in STAR’s Au+Au 7.7 Gev collisions.

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“…[28] and for related works see Refs. [29][30][31][32][33]). In the perfect-fluid approach to hydrodynamics with spin, proposed in Ref.…”

Section: Introductionmentioning

confidence: 99%

Longitudinal spin polarization in a thermal model

et al. 2019

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We use a thermal model with single freeze-out to determine longitudinal polarization of Λ hyperons emitted from a hot and rotating hadronic medium. We consider the top RHIC energies and use the model parameters determined in the previous analyses of particle spectra and elliptic flow. Using a direct connection between the spin polarization tensor and thermal vorticity, we reproduce earlier results which indicate a quadrupole structure of the longitudinal component of the polarization three-vector with an opposite sign compared to that found in the experiment. We further use only the spatial components of the thermal vorticity in the laboratory system to define polarization and show that this leads to the correct sign and magnitude of the quadrupole structure. This procedure resembles a non-relativistic connection between the polarization three-vector and vorticity employed in other works. In general, our results bring further evidence that the spin polarization dynamics in heavy-ion collisions may be not directly related to the thermal vorticity. The additional material explains the construction of the hydrodynamicaly consistent gradients of fluid velocity and temperature in thermal models with the help of the perfect-fluid equations of motion.

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Fluid dynamics study of the $$\varLambda $$ polarization for Au + Au collisions at $$\sqrt{s_{NN}}=200$$ GeV

Cited by 32 publications

References 33 publications

Relaxation time for the alignment between the spin of a finite-mass quark or antiquark and the thermal vorticity in relativistic heavy-ion collisions

Relaxation time for the alignment between the spin of a finite-mass quark or antiquark and the thermal vorticity in relativistic heavy-ion collisions

A study of $$\varLambda $$ and $$\bar{\varLambda }$$ polarization splitting by meson field in PICR hydrodynamic model

Longitudinal spin polarization in a thermal model

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