Conveners
Parallel Session T02: Chirality, vorticity and spin polarization: I
- Michael Lisa
Parallel Session T02: Chirality, vorticity and spin polarization: II
- Dirk Rischke (University Frankfurt)
Parallel Session T02: Chirality, vorticity and spin polarization: III
- Jurgen Schukraft (University of Copenhagen (DK))
In non-central heavy-ion collisions (HIC), the large initial angular momentum can induce a non-vanishing polarization for hadrons with non-zero spin. The global spin alignment of vector mesons, quantified by the $00^{th}$ element of spin density matrix ($\rho_{00}$), can offer information on the spin-orbital interactions of the QCD medium. Surprisingly large signal of vector meson $\rho_{00}$...
Polarization and spin-alignment measurements represent an important tool for the understanding of the particle production mechanisms occurring in proton–proton collisions. When considering heavy-ion collisions, quarkonium polarization could also be used to investigate the characteristics of the hot and dense medium (quark-gluon plasma) created at LHC energies. In ALICE, this observable was...
The physics interpretation of the recent measurements of the spin polarization of Λ hyperons produced in relativistic heavy-ion collisions is discussed. It is suggested 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...
Recent observations for the spin polarization and alignments in RHIC and LHC have triggered intensive studies for vorticity-induced polarization and spin dynamics in relativistic fluids. We study the important, yet widely overlooked, role of gluons for spin transport with a connection to local parity violation in quark gluon plasmas. We extend the newly developed quantum kinetic theory for...
By including the recently introduced thermal shear term of the spin polarization vector at local equilibrium we determine longitudinal polarization of Λ hyperons emitted from a hot and rotating hadronic medium using the thermal model with single freeze-out. In our analysis we consider top RHIC energy and use the model parameters which were determined in the previous analyses of particle...
The measurements of spin polarization of particles emitted in heavy-ion collisions has opened the possibility for new phenomenological investigations of spin physics in relativistic fluids. The theoretical predictions of global polarization are in agreement with the data, but consistent discrepancies stand out for the local polarization. In this talk, I will show that the covariant theory of...
The local Lambda polarization puzzle associated with the model calculations by thermal vorticity has attracted lots of attention in heavy ion community [1].
In addition to the widely studied thermal vorticity effect, we identify an undiscovered contribution from the fluid shear [2]. We obtain the explicit expression for shear-induced polarization (SIP) from quantum kinetic equation and...
Using the second law of local thermodynamics and the first-order Palatini formalism, we formulate relativistic spin hydrodynamics for quantum field theories with Dirac fermions, such as QED and QCD, in a torsionful curved background. We work in a regime where spin density, which is assumed to relax much slower than other non-hydrodynamic modes, is treated as an independent degree of freedom in...
Observations of strong azimuthal anisotropies ($v_n$)-- and their agreement with some hydrodynamic calculations-- in p+A collisions at RHIC and LHC have led to the suggestion that such collisions produce the smallest droplets of QGP. This hypothesis may be tested from a different angle through hyperon polarization measurements. In particular, central p+A collisions may naturally produce an...
Suppression of charmonia is one of the most distinctive signatures of Quark-Gluon Plasma (QGP) in heavy-ion collisions. Suppression can also take place in hadron-nucleus collisions due to cold nuclear matter (CNM) effects where the presence of QGP is not expected. The hadron-nucleus collisions are therefore important as they help to disentangle the effects of the QGP from those due to CNM....
Charge-dependent azimuthal anisotropy Fourier coefficients are measured with two- and three-particle correlations in pPb and PbPb collisions. The difference between positively and negatively charged particles for the second-order two-particle $(v_2\{2\})$ and three-particle $(v_2\{3\})$ coefficients for both pPb and PbPb, and third order two-particle coefficient $(v_3\{2\})$ for PbPb, are...
We derive a semi-classical kinetic theory for massive spin-1 particles from the Wigner-function formalism.
Starting from an interacting Proca Lagrangian, we obtain equations of motion for the Wigner function of massive charged vector bosons in classical electromagnetic fields. Performing a power-expansion up to first order in the Planck constant $\hbar$, we then derive generalized...
The quark-gluon plasma (QGP) is a fluid at a long wavelength and becomes a collection of weakly-coupled partons at an asymptotically short wavelength. However, its properties at the "mesoscopic" length scale, which is too short for a fluid description and too long for a perturbative treatment, remain elusive. In this work, we consider the response of QCD-like plasma to energy/momentum...
In heavy-ion collisions, the observation of the global hyperon polarization, $\overline{P}_\mathrm{H}$, ranging from $\sqrt{s_\mathrm{NN}}=7.7$~GeV to 5.02~TeV has revealed the existence of large vorticities perpendicular to the reaction plane due to system's orbital angular momentum. We present recent results on $\overline{P}_\mathrm{H}$, and differential measurements thereof, extended to the...
Quantum Chromodynamics allows for the formation of parity-odd domains inside the medium produced in heavy-ion collisions associated with a net chirality of the quarks. As a consequence, the Chiral Magnetic Effect (CME) and Chiral Vortical Effect (CVE) are phenomena predicted to occur and cause electric-charge and baryonic-charge separation along the direction of the magnetic field and...
