Abstract
Dilepton production in heavy-ion collisions at top SPS energy is investigated within a coarse-graining approach that combines an underlying microscopic evolution of the nuclear reaction with the application of medium-modified spectral functions. Extracting local energy and baryon density for a grid of small space-time cells and going to each cell's rest frame enables to determine local temperature and chemical potential by application of an equation of state. This allows for the calculation of thermal dilepton emission. We apply and compare two different spectral functions for the $\rho$: A hadronic many-body calculation and an approach that uses empirical scattering amplitudes. Quantitatively good agreement of the model calculations with the data from the NA60 collaboration is achieved for both spectral functions, but in detail the hadronic many-body approach leads to a better description, especially of the broadening around the pole mass of the $\rho$ and for the low-mass excess. We further show that the presence of a pion chemical potential significantly influences the dilepton yield.
Highlights
Lepton pairs came into the focus of interest as probes for the creation of a deconfined phase [1,2,3], the so-called quark-gluon plasma (QGP), the hadronic contributions to dilepton production have become a field of vigorous theoretical investigation on their own [4,5,6,7]
We have presented calculations of the thermal dilepton yield for In+In collisions at top SPS energy from coarse-grained microscopic dynamics
The results show a good agreement with the measurements of the NA60 collaboration
Summary
Lepton pairs came into the focus of interest as probes for the creation of a deconfined phase [1,2,3], the so-called quark-gluon plasma (QGP), the hadronic contributions to dilepton production have become a field of vigorous theoretical investigation on their own [4,5,6,7]. Detailed investigations might help to understand how the high-energy regime with partonic degrees of freedom is connected to the non-perturbative low-energy part, where quarks and gluons are confined in hadrons Another aspect of study is the symmetry pattern of QCD which is expected to change from its vacuum properties when going to finite temperature and baryochemical potential. As the reactions in a heavy-ion collision are governed by the strong interaction, one has to deal with complications such as multi-particle collisions, finite temperature and density corrections to form factors and widths, off-shell dynamics, etc These aspects impose high requirements on theoretical descriptions that model the dilepton production in heavy-ion collisions.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
