6 research outputs found
Centrality dependence of photon yield and elliptic flow from gluon fusion and splitting induced by magnetic fields in relativistic heavy-ion collisions
We compute the photon yield and elliptic flow coefficient in relativistic
heavy-ion collisions from gluon fusion and splitting processes induced by a
magnetic field for different centralities. The calculation accounts for the
intense magnetic field and the high gluon occupation number at early times. The
photon production induced by these process represents an excess contribution
over calculations without magnetic field effects. We compare this excess to the
difference between PHENIX data and recent hydrodynamic calculations for the
photon transverse momentum distribution and elliptic flow coefficient .
The time evolution of the field strength and reaction volume is computed using
UrQMD. We show that with reasonable values for the saturation scale, the
calculation helps to better describe the experimental results obtained at RHIC
energies for the lowest part of the transverse photon momentum at different
centralities.Comment: Expanded discussion. Version to appear in The European Physical
Journal
Thermodynamics of an updated hadronic resonance list and influence on hadronic transport
Hadron lists based on experimental studies summarized by the Particle Data
Group (PDG) are a crucial input for the equation of state and thermal models
used in the study of strongly-interacting matter produced in heavy-ion
collisions. Modeling of these strongly-interacting systems is carried out via
hydrodynamical simulations, which are followed by hadronic transport codes that
also require a hadronic list as input. To remain consistent throughout the
different stages of modeling of a heavy-ion collision, the same hadron list
with its corresponding decays must be used at each step. It has been shown that
even the most uncertain states listed in the PDG from 2016 are required to
reproduce partial pressures and susceptibilities from Lattice Quantum
Chromodynamics with the hadronic list known as the PDG2016+. Here, we update
the hadronic list for use in heavy-ion collision modeling by including the
latest experimental information for all states listed in the Particle Data
Booklet in 2021. We then compare our new list, called PDG2021+, to Lattice
Quantum Chromodynamics results and find that it achieves even better agreement
with the first principles calculations than the PDG2016+ list. Furthermore, we
develop a novel scheme based on intermediate decay channels that allows for
only binary decays, such that PDG2021+ will be compatible with the hadronic
transport framework SMASH. Finally, we use these results to make comparisons to
experimental data and discuss the impact on particle yields and spectra.Comment: 17 pages, 16 figures, 2 table
Gluon polarization tensor and dispersion relation in a weakly magnetized medium
We study the polarization and dispersion properties of gluons moving within a weakly magnetized background at one-loop order. To this end, we show two alternative derivations of the charged fermion propagator in the weak field expansion and use this expression to compute the lowest order magnetic field correction to the gluon polarization tensor. We explicitly show that, in spite of its cumbersome appearance, the gluon polarization tensor is transverse as required by gauge invariance. We also show that none of the three polarization modes develops a magnetic mass and that gluons propagate along the light cone, non withstanding that Lorentz invariance is lost due to the presence of the magnetic field. We also study the strength of the polarization modes for real gluons. We conclude that the lowest order approximation to the gluon polarization and dispersion properties is good as long as the field strength and gluon momentum are not larger than the loop fermion mass. When the fermion mass is the vacuum one, the applicability of these findings for phenomenological studies is rather limited. However, should temperature be accounted for and the fermion mass become the thermal one, conditions met during the plasma phase of a heavy-ion collision, these findings can be potentially very useful to describe gluon mediated processes in the presence of a magnetic field
Thermodynamics of an updated hadronic resonance list and influence on hadronic transport
Hadron lists based on experimental studies summarized by the Particle Data Group (PDG) are a crucial input for the equation of state and thermal models used in the study of strongly-interacting matter produced in heavy-ion collisions. Modeling of these strongly-interacting systems is carried out via hydrodynamical simulations, which are followed by hadronic transport codes that also require a hadronic list as input. To remain consistent throughout the different stages of modeling of a heavy-ion collision, the same hadron list with its corresponding decays must be used at each step. It has been shown that even the most uncertain states listed in the PDG from 2016 are required to reproduce partial pressures and susceptibilities from Lattice Quantum Chromodynamics with the hadronic list known as the PDG2016+. Here, we update the hadronic list for use in heavy-ion collision modeling by including the latest experimental information for all states listed in the Particle Data Booklet in 2021. We then compare our new list, called PDG2021+, to Lattice Quantum Chromodynamics results and find that it achieves even better agreement with the first principles calculations than the PDG2016+ list. Furthermore, we develop a novel scheme based on intermediate decay channels that allows for only binary decays, such that PDG2021+ will be compatible with the hadronic transport framework SMASH. Finally, we use these results to make comparisons to experimental data and discuss the impact on particle yields and spectra