Frankfurt Institute for Advanced Studies

About: Frankfurt Institute for Advanced Studies is a facility organization based out in Frankfurt am Main, Germany. It is known for research contribution in the topics: Baryon & Quark–gluon plasma. The organization has 798 authors who have published 2733 publications receiving 82799 citations. The organization is also known as: FIAS.

Effect of the QCD equation of state and strange hadronic resonances on multiparticle correlations in heavy ion collisions

Abstract: The QCD equation of state at zero baryon chemical potential is the only element of the standard dynamical framework to describe heavy ion collisions that can be directly determined from first principles. Continuum extrapolated lattice QCD equations of state have been computed using 2+1 quark flavors (up/down and strange) as well as 2+1+1 flavors to investigate the effect of thermalized charm quarks on QCD thermodynamics. Lattice results have also indicated the presence of new strange resonances that not only contribute to the equation of state of QCD matter but also affect hadronic afterburners used to model the later stages of heavy ion collisions. We investigate how these new developments obtained from first principles calculations affect multiparticle correlations in heavy ion collisions. We compare the commonly used equation of state S95n-v1, which was constructed using what are now considered outdated lattice results and hadron states, to the current state-of-the-art lattice QCD equations of state with 2+1 and 2+1+1 flavors coupled to the most up-to-date hadronic resonances and their decays. New hadronic resonances lead to an enhancement in the hadronic spectra at intermediate ${p}_{T}$. Using an outdated equation of state can directly affect the extraction of the shear viscosity to entropy density ratio, $\ensuremath{\eta}/s$, of the quark-gluon plasma and results for different flow observables. The effects of the QCD equation of state on multiparticle correlations of identified particles are determined for both AuAu $\sqrt{{s}_{\text{NN}}}=200$ GeV and PbPb $\sqrt{{s}_{\text{NN}}}=5.02$ TeV collisions. New insights into the ${v}_{2}{2}$ to ${v}_{3}{2}$ puzzle in ultracentral collisions are found. Flow observables of heavier particles exhibit more nonlinear behavior regardless of the assumptions about the equation of state, which may provide a new way to constrain the temperature dependence of $\ensuremath{\eta}/s$.

Bulk matter evolution and extraction of jet transport parameters in heavy-ion collisions at energies available at the BNL Relativistic Heavy Ion Collider (RHIC)

Abstract: Within the picture of jet quenching induced by multiple parton scattering and gluon bremsstrahlung, medium modification of parton fragmentation functions and therefore the suppression of large transverse-momentum hadron spectra are controlled by both the value and the space-time profile of the jet transport parameter along the jet propagation path Experimental data on single-hadron suppression in high-energy heavy-ion collisions at the Relativistic Heavy Ion Collider energy are analyzed within the higher-twist (HT) approach to the medium-modified fragmentation functions and the next-to-leading order perturbative QCD parton model Assuming that the jet transport parameter $\mathrm{q\ifmmode \hat{}\else \^{}\fi{}}$ is proportional to the particle number density in both quark gluon plasma (QGP) and hadronic phase, experimental data on jet quenching in deeply inelastic scattering off nuclear targets can provide guidance on ${\mathrm{q\ifmmode \hat{}\else \^{}\fi{}}}_{h}$ in the hot hadronic matter One can then study the dependence of the extracted initial value of jet-quenching parameter ${\mathrm{q\ifmmode \hat{}\else \^{}\fi{}}}_{0}$ at initial time ${\ensuremath{\tau}}_{0}$ on the bulk medium evolution Effects of transverse expansion, radial flow, phase transition, and nonequilibrium evolution are examined The extracted values are found to vary from ${\mathrm{q\ifmmode \hat{}\else \^{}\fi{}}}_{0}{\ensuremath{\tau}}_{0}=054$ GeV${}^{2}$ in the ($1+3$)d ideal hydrodynamic model to 096 GeV${}^{2}$ in a cascade model, with the main differences coming from the initial nonequilibrium evolution and the later hadronic evolution The overall contribution to jet quenching from the hadronic phase, about $22%--44$$%$, is found to be significant Therefore, a realistic description of the early nonequilibrium parton evolution and later hadronic interaction will be critical for accurate extraction of the jet transport parameter in the strongly interacting QGP phase in high-energy heavy-ion collisions

Computational epitope map of SARS-CoV-2 spike protein.

Abstract: The primary immunological target of COVID-19 vaccines is the SARS-CoV-2 spike (S) protein. S is exposed on the viral surface and mediates viral entry into the host cell. To identify possible antibody binding sites, we performed multi-microsecond molecular dynamics simulations of a 4.1 million atom system containing a patch of viral membrane with four full-length, fully glycosylated and palmitoylated S proteins. By mapping steric accessibility, structural rigidity, sequence conservation, and generic antibody binding signatures, we recover known epitopes on S and reveal promising epitope candidates for structure-based vaccine design. We find that the extensive and inherently flexible glycan coat shields a surface area larger than expected from static structures, highlighting the importance of structural dynamics. The protective glycan shield and the high flexibility of its hinges give the stalk overall low epitope scores. Our computational epitope-mapping procedure is general and should thus prove useful for other viral envelope proteins whose structures have been characterized.

Production and elliptic flow of dileptons and photons in a matrix model of the quark-gluon plasma.

Abstract: We consider a nonperturbative approach to the thermal production of dileptons and photons at temperatures near the critical temperature in QCD. The suppression of colored excitations at low temperature is modeled by including a small value of the Polyakov loop, in a "semi"-quark-gluon plasma (QGP). Comparing the semi-QGP to the perturbative QGP, we find a mild enhancement of thermal dileptons. In contrast, to leading logarithmic order in weak coupling there are far fewer hard photons from the semi-QGP than the usual QGP. To illustrate the possible effects on photon and dilepton production in heavy-ion collisions, we integrate the rate with a simulation using ideal hydrodynamics. Dileptons uniformly exhibit a small flow, but the strong suppression of photons in the semi-QGP tends to weight the elliptical flow of photons to that generated in the hadronic phase.