Thu·Dec 17, 2020Thursday·December 17, 2020

1. 01*

   Heavy Ions, Experimental Overview

   Yvonne Pachmayer🇩🇪

   This article gives an overview of recent highlights from experimental measurements of heavy-ion collisions at ultra-relativistic energies: Measurements of electroweak probes constrain both the initial collision geometry and the nuclear parton distribution functions. Results from soft particle production show that the abundance of light-flavour hadrons from pions up to hypertriton and ${}^4$He can be described by a universal temperature and that these participate in the collective motion of the system. There are hints of these effects also in small systems, which will be further investigated in future to understand the underlying mechanisms. Studies of hard probes, such as heavy quarks and jets show that parton energy loss plays an important role in heavy-ion collisions. Differential measurements of J/$\psi$ mesons elucidate their production mechanism, i.e.\ regeneration, and give evidence for deconfinement in Pb--Pb collisions at LHC full energy. The large data samples at the LHC enable studies of rare probes such as ${\chi }_{c1}$(3872) and top--anti-top production. Further, measurements of antinuclei cross sections can provide input for dark matter searches.

   nucl-exhep-exPoS(2021)·1 citation
2. 02*

   Recent advances in the quantification of uncertainties in reaction theory

   A.E. Lovell🇺🇸 · F.M. Nunes🇺🇸 · M. Catacora-Rios · G.B. King🇺🇸

   Uncertainty quantification has become increasingly more prominent in nuclear physics over the past several years. In few-body reaction theory, there are four main sources that contribute to the uncertainties in the calculated observables: the effective potentials, approximations made to the few-body problem, structure functions, and degrees of freedom left out of the model space. In this work, we illustrate some of the features that can be obtained when modern statistical tools are applied in the context of nuclear reactions. This work consists of a summary of the progress that has been made in quantifying theoretical uncertainties in this domain, focusing primarily on those uncertainties coming from the effective optical potential as well as their propagation within various reaction theories. We use, as the central example, reactions on the doubly-magic stable nucleus ${}^{40}$Ca, namely neutron and proton elastic scattering and single-nucleon transfer ${}^{40}$Ca(d,p)${}^{41}$Ca. First, we show different optimization schemes used to constrain the optical potential from differential cross sections and other experimental constraints; we then discuss how these uncertainties propagate to the transfer cross section, comparing two reaction theories. We finish by laying out our future plans.

   ↳ nucl-thnucl-exJ.Phys.G(2020)·34 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.