Wed·Oct 16, 2019Wednesday·October 16, 2019

1. 01*

   Reference Database for Photon Strength Functions

   S. Goriely🇧🇪 · P. Dimitriou🇦🇹 · M. Wiedeking🇿🇦 · T. Belgya🇭🇺 · R. Firestone🇺🇸 · J. Kopecky · M. Krticka🇨🇿 · V. Plujko🇺🇦 · R. Schwengner🇩🇪 · S. Siem🇳🇴 · H. Utsunomiya🇯🇵 · S. Hilaire🇫🇷 and 7 other authors

   Photon strength functions describing the average response of the nucleus to an electromagnetic probe are key input information in the theoretical modelling of nuclear reactions. Consequently they are important for a wide range of fields such as nuclear structure, nuclear astrophysics, medical isotope production, fission and fusion reactor technologies. They are also sources of information for widely used reaction libraries such as the IAEA Reference Input Parameter Library and evaluated data files such as EGAF. In the past two decades, the amount of reaction gamma-ray data measured to determine photon strength functions has grown rapidly. Different experimental techniques have led to discrepant results and users are faced with the dilemma which (if any) of the divergent data to adopt. We report on a coordinated effort to compile and assess the existing experimental data on photon strength functions from the giant dipole resonance region to energies below the neutron separation energy. The assessment of the discrepant data at energies around or below the neutron separation energy has been possible only in a few cases where adequate information on the model-dependent analysis and estimation of uncertainties was available. In the giant dipole resonance region, we adopt the recommendations of the new IAEA photonuclear data library. We also present global empirical and semi-microscopic models that describe the photon strength functions in the entire energy region and reproduce reasonably well most of the experimental data. The compiled experimental photon strengths and recommended model calculations are available from the PSF database hosted at the IAEA (URL:www-nds.iaea.org/PSFdatabase).

   nucl-exEPJA(2019)·130 citations
2. 02*

   Chemical equilibration of QGP in hadronic collisions

   Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇨🇭

   We performed state-of-the-art QCD effective kinetic theory simulations of chemically equilibrating QGP in longitudinally expanding systems. We find that chemical equilibration takes place after hydrodynamization, but well before local thermalization. By relating the transport properties of QGP and the system size we estimate that hadronic collisions with final state multiplicities $d{N}_{\text{ch}}/d\eta >10^2$ live long enough to reach approximate chemical equilibrium for all collision systems. Therefore we expect the saturation of strangeness enhancement to occur at the same multiplicity in proton-proton, proton-nucleus and nucleus-nucleus collisions.

   ↳ hep-phnucl-exnucl-thSpringer Proc.Phys.(2020)·2 citations
3. 03*

   Quarkonium measurements at forward rapidity with ALICE at the LHC

   Wadut Shaikh (for the ALICE Collaboration)🇮🇳

   Heavy quarks are produced at the first instant of a nucleus--nucleus collision and therefore are an important tool to study the subsequent high energy-density medium formed in ultra-relativistic heavy-ion collisions. A series of experimental efforts for understanding the properties of the Quark--Gluon Plasma (QGP), a medium consisting of a deconfined state of quarks and gluons, are based on measuring the bound states of heavy quark--anti-quark pairs known as quarkonia. However, the medium modification of heavy-flavour hadron production includes also the contribution of Cold Nuclear Matter (CNM) effects such as shadowing or nuclear breakup in addition to the QGP effects. Proton--nucleus collisions, where no QGP is expected, are used to measure CNM effects on quarkonium production. Finally, quarkonium measurements in proton--proton collisions are used as reference for both heavy-ion and proton-ion collisions. ALICE measurements of quarkonia at forward rapidity for various energies and colliding systems (pp, p--Pb, Pb--Pb and Xe--Xe) during the LHC Run 1 and Run 2 periods will be discussed.

   ↳ hep-exnucl-exSpringer Proc.Phys.(2020)·1 citation
4. 04*

   Spin Polarizations in a Covariant Angular-Momentum-Conserved Chiral Transport Model

   Shuai Y.F. Liu🇺🇸 · Yifeng Sun🇮🇹 · Che Ming Ko🇺🇸

   Using a covariant and angular-momentum-conserved chiral transport model, which takes into account the spin-orbit interactions of chiral fermions in their scatterings via the side jumps, we study the quark spin polarization in quark matter. For a system of rotating and unpolarized massless quarks in an expanding box, we find that side jumps can dynamically polarize the quark spin and result in a final quark spin polarization consistent with that of thermally equilibrated massless quarks in a self-consistent vorticity field. For the quark matter produced in noncentral relativistic heavy ion collisions, we find that in the medium rest frame both the quark local spin polarizations in the direction perpendicular to the reaction plane and along the longitudinal beam direction show an azimuthal angle dependence in the transverse plane similar to those observed in experiments for the Lambda hyperon.

   ↳ nucl-thhep-phnucl-exPRL(2020)·107 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.