60 research outputs found
Lambda polarization in heavy ion collisions: from RHIC BES to LHC energies
STAR collaboration at RHIC has recently measured the polarization of
hyperons in non-central heavy ion collisions in the RHIC Beam Energy
Scan (BES) program. The magnitude of the polarization was found to decrease
from few percents at the lowest BES energies to % at the top RHIC
energy. The polarization signal has been reproduced in different hydrodynamic
calculations assuming a thermodynamic spin-vorticity coupling mechanism at the
Cooper-Frye hypersurface.
In this work an extension of our existing calculations of the
polarization in the RHIC BES program to the top RHIC and 2.76 TeV LHC energies
is presented. The longitudinal component of the polarization, which
is the dominant component of the polarization at the LHC energies, is
discussed. Finally we show that the global polarization of originates
dominantly from the relativistic analogue of the classical vorticity, whereas
the quadrupole longitudinal component originates from the gradients of
temperature and acceleration of the medium when the s are produced out
of the fluid.Comment: talk given at Quark Matter 2018 conference (Venice, Italy, 13-19 May
2018). 4 pages, 2 figure
Collective flow in (anti)proton-proton collision at Tevatron and LHC
Collective flow as a consequence of hydrodynamical evolution in heavy ion
collisions is intensively studied by theorists and experimentalists to
understand the behavior of hot quark matter. Due to their large mass, heavy
ions suffer collective effects even at low (SPS) or intermediate energies
(RHIC). In case of light systems such as (anti)proton-proton interactions,
collective effects was not expected. Within a global model such as EPOS, where
light and heavy systems are treated using the same physics, it appears that
Tevatron data are better described if a flow is introduced. Then the
extrapolation to LHC can easily be done and we can compare to first data from
ATLAS experiment.Comment: 4 pages, 6 figures, Proceeding of the 45th Rencontres de Moriond QC
The Evolving Concept of Cardiac Conduction System Pacing
Cardiac pacing is an established treatment option for patients with bradycardia and heart failure. In the recent decade, there is an increasing scientific and clinical interest in the topic of direct His bundle pacing (HBP) and left bundle branch pacing (LBBP) as options for cardiac conduction system pacing (CSP). The concept of CSP started evolving from the late 1970s, passing several historical landmarks. HBP and LBBP used in CSP proved to be successful in small cohorts of patients with various clinical conditions, including binodal disease, atrioventricular blocks, and in patients with bundle branch blocks with indications for cardiac resynchronization therapy. The scope of this chapter is synthesis and analysis of works devoted to this subject, as well as representation of the author’s experience in this topic. The chapter includes historical background, technical, anatomical, and clinical considerations of CSP, covers evidence base, discusses patient outcomes in line with the pros and cons of the abovementioned methods. The separate part describes practical aspects of different pacing modalities, including stages of the operation and pacemaker programming. The textual content of the chapter is accompanied by illustrations, ECGs, and intracardiac electrograms
Particle production in a hybrid approach for a beam energy scan of Au+Au/Pb+Pb collisions between = 4.3 GeV and = 200.0 GeV
Heavy-ion collisions at varying collision energies provide access to
different regions of the QCD phase diagram. In particular collisions at
intermediate energies are promising candidates to experimentally identify the
postulated first order phase transition and critical end point.
While heavy-ion collisions at low and high collision energies are
theoretically well described by transport approaches and
hydrodynamics+transport hybrid approaches, respectively, intermediate energy
collisions remain a challenge.
In this work, a modular hybrid approach, the SMASH-vHLLE-hybrid coupling 3+1D
viscous hydrodynamics (vHLLE) to hadronic transport (SMASH), is introduced. It
is validated and subsequently applied in Au+Au/Pb+Pb collisions between
= 4.3 GeV and = 200.0 GeV to
study the rapidity and transverse mass distributions of identified particles as
well as excitation functions for and
. A good agreement with experimental measurements
is obtained, including the baryon stopping dynamics. The transition from a
Gaussian rapidity spectrum of protons at lower energies to the double-hump
structure at high energies is reproduced. The centrality and energy dependence
of charged particle is also described reasonably well. This work serves
as a basis for further studies, e.g. systematic investigations of different
equations of state or transport coefficients
A New Model for Jet Energy Loss in Heavy Ion Collisions
We present a new model for jet quenching from coherent radiation in a brick
medium. The jet energy loss is simulated as a perturbative final-state vacuum
parton shower followed by a medium-induced shower originating from elastic and
radiative collisions with the medium constituents. Coherency is achieved by
starting with trial gluons that act as field dressing of the initial jet
parton. These are formed according to a Gunion-Bertsch seed. The QCD version of
the LPM effect is attained by increasing the phase of the trial gluons through
elastic scatterings with the medium. Above a phase threshold, the trial gluons
will be realised and can produce coherent radiation themselves. The model has
been implemented in a Monte Carlo code and has been validated by successfully
reproducing the BDMPS-Z prediction for the energy spectrum. The realistic case
with minimal assumptions are also produced and shown. In particular, we show
the influence of various parameters on the energy spectrum and transverse
momentum distribution, such as the in-medium quark masses, the energy transfer
in the recoil process, and the phase accumulation criteria, especially for low
and intermediate energy gluons. Future studies will allow for the interface
with full simulations of the quark-gluon-plasma with hydrodynamic evolution,
such as vHLLE, along with subsequent hadronisation of the jet partons in order
to produce realistic distributions that can be directly compared to LHC and
RHIC data.Comment: Proceedings for Hard Probes 2023 (Aschaffenburg, Germany, 26-31 March
2023). 6 pages, 8 figure
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