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The Facility for Antiproton and Ion Research (FAIR) is currently being built in Darmstadt, Germany. The SIS100 accelerator is at the heart of FAIR and will provide proton and heavy-ion beams for a variety of experiments. There are four main research pillars at FAIR specialized in the field of nuclear, hadron and elementary particle physics, atomic and antimatter physics, high density plasma physics, as well as applications in condensed matter physics, biology and the biomedical sciences. In these proceedings I briefly review the main research pillars of FAIR and the status of its realization.

A bstract Transverse momentum spectra of identified particles produced in heavy-ion collisions at the Large Hadron Collider are described with relativistic fluid dynamics. We perform a systematic comparison of experimental data for pions, kaons and protons up to a transverse momentum of 3 GeV /c with calculations using the F luid u M code package to solve the evolution equations of fluid dynamics, the T r ENT o model to describe the initial state and the F ast R eso code to take resonance decays into account. Using data in five centrality classes at the center-of-mass collision energy per nucleon pair s NN = 2 . 76 TeV, we determine systematically the most likely parameters of our theoretical model including the shear and bulk viscosity to entropy ratios, the initialization time, initial density and freeze-out temperature through a global search and quantify their posterior probability. This is facilitated by the very efficient numerical implementation of F luid u M and F ast R eso . Based on the most likely model parameters we present predictions for the transverse momentum spectra of multi-strange hadrons as well as identified particle spectra from Pb-Pb collisions at s NN = 5 . 02 TeV.

The size and evolution of the medium created in a heavy-ion collision depends on collision geometry. Experimentally collisions can be characterized by the measured particle multiplicities around midrapidity or by the energy measured in the forward rapidity region, which is sensitive to the spectator fragments. In the Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) the multiplicity of produced particles is measured with the silicon tracking system (STS). The projectile spectator detector (PSD) measures the energy of spectator fragments. We present the procedure of collision centrality determination in CBM and its performance using the PSD and the STS information.

Differential measurements of the directed flow of protons of Au+Au collisions at the beam energy of 1.23AGeV collected by the HADES experiment at SIS18 are presented. Measurements are performed with respect to the spectator symmetry plane estimated using the Forward Wall hodoscope. Corrections for the detector azimuthal non-uniformity are applied. Event plane and scalar product methods are used to evaluate the systematic uncertainty.

The evolution of matter created in a heavy-ion collision depends on its initial geometry. Experimentally collision geometry is characterized with centrality. Procedure of centrality determination for the Compressed Baryonic Matter (CBM) experiment at FAIR is presented. Relation between parameters of the collision geometry (such as impact parameter magnitude) and centrality classes is extracted using multiplicity of produced charged particles. The latter is connected to the collision geometry parameters using Monte-Carlo Glauber approach.

A bstract The exclusive photoproduction reactions γp → J/ψ (1 S ) p and γp → ψ (2 S ) p have been measured at an ep centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 373 pb − 1 . The measurement was made in the kinematic range 30 < W < 180 GeV, Q 2 < 1 GeV 2 and | t | < 1 GeV 2 , where W is the photon-proton centre-of-mass energy, Q 2 is the photon virtuality and t is the squared four-momentum transfer at the proton vertex. The decay channels used were J/ψ (1 S ) → μ + μ − , ψ (2 S ) → μ + μ − and ψ (2 S ) → J/ψ (1 S ) π + π − with subsequent decay J/ψ (1 S ) → μ + μ − . The ratio of the production cross sections, R = σ ψ (2 S ) /σ J/ψ (1 S ) , has been measured as a function of W and | t | and compared to previous data in photoproduction and deep inelastic scattering and with predictions of QCD-inspired models of exclusive vector-meson production, which are in reasonable agreement with the data.

The Compressed Baryonic Matter experiment (CBM) performance for proton anisotropic flow measurements is studied with Monte-Carlo simulations using collisions of gold ions at lab momentum of 12 A GeV/ c employing DCM-QGSM-SMM heavy-ion event generator. Realistic procedures are used for centrality estimation with the number of registered tracks and particle identification with information from Time-Of-Flight detector. Variation of directed flow estimates depending on various combinations of PSD modules is used to evaluate possible systematic biases due to collision symmetry plane estimation.

The azimuthal correlation angle,$$\\Delta \\phi $$Δ ϕ , between the scattered lepton and the leading jet in deep inelastic$$e^{\\pm }p$$e ± p scattering at HERA has been studied using data collected with the ZEUS detector at a centre-of-mass energy of$$\\sqrt{s} = 318 {\\,\\text {Ge}\\hspace{-0.66666pt}\\text {V}}$$s = 318 Ge V , corresponding to an integrated luminosity of$$326 \\,\\text {pb}^{-1}$$326 pb - 1 . A measurement of jet cross sections in the laboratory frame was made in a fiducial region corresponding to photon virtuality$$10 {\\,\\text {Ge}\\hspace{-0.66666pt}\\text {V}}^2< Q^2 < 350 {\\,\\text {Ge}\\hspace{-0.66666pt}\\text {V}}^2$$10 Ge V 2 < Q 2 < 350 Ge V 2 , inelasticity$$0.04< y < 0.7$$0.04 < y < 0.7 , outgoing lepton energy$$E_e > 10 {\\,\\text {Ge}\\hspace{-0.66666pt}\\text {V}}$$E e > 10 Ge V , lepton polar angle$$140^\\circ< \\theta _e < 180^\\circ $$140 ∘ < θ e < 180 ∘ , jet transverse momentum$$2.5 {\\,\\text {Ge}\\hspace{-0.66666pt}\\text {V}}< p_\\textrm{T,jet} < 30 {\\,\\text {Ge}\\hspace{-0.66666pt}\\text {V}}$$2.5 Ge V < p T,jet < 30 Ge V , and jet pseudorapidity$$-1.5< \\eta _\\textrm{jet} < 1.8$$- 1.5 < η jet < 1.8 . Jets were reconstructed using the$$k_\\textrm{T}$$k T algorithm with the radius parameter$$R = 1$$R = 1 . The leading jet in an event is defined as the jet that carries the highest$$p_\\textrm{T,jet}$$p T,jet . Differential cross sections,$$d\\sigma /d\\Delta \\phi $$d σ / d Δ ϕ , were measured as a function of the azimuthal correlation angle in various ranges of leading-jet transverse momentum, photon virtuality and jet multiplicity. Perturbative calculations at$$\\mathcal {O}(\\alpha _{s}^2)$$O ( α s 2 ) accuracy successfully describe the data within the fiducial region, although a lower level of agreement is observed near$$\\Delta \\phi \\rightarrow \\pi $$Δ ϕ → π for events with high jet multiplicity, due to limitations of the perturbative approach in describing soft phenomena in QCD. The data are equally well described by Monte Carlo predictions that supplement leading-order matrix elements with parton showering.

Estimate of the collision symmetry planes is a crucial part of the anisotropic flow analysis in heavy-ion collisions. HADES experiment at GSI has different possibilities for symmetry plane estimation. In this letter different methods of the symmetry plane resolution calculation are compared and the differences are explained in terms of non-flow contribution.