29 research outputs found
Thermal Energy of a Charm-meson Molecule in a Pion Gas
The thermal corrections to the propagator of a loosely bound charm-meson
molecule in a pion gas are calculated to next-to-leading order in the
heavy-meson expansion using a zero-range effective field theory. Ultraviolet
divergences in the charm-meson-pair self energy are canceled by corrections to
the charm-meson-pair contact vertex. Terms that are singular at the
charm-meson-pair threshold can be absorbed into thermal corrections to the rest
energies and kinetic masses of the charm-meson constituents. The remaining
terms reduce to a thermal correction to the binding momentum that is
proportional to the pion number density and suppressed by the pion/charm-meson
mass ratio. The correction gives a tiny decrease in the binding energy of the
charm-meson molecule relative to the charm-meson-pair threshold in the pion gas
and a change in its thermal width that is small compared to the thermal widths
of the charm-meson constituents. These results are encouraging for the
prospects of observing and in the expanding hadron
gas produced by heavy-ion collisions.Comment: 37 pages, 10 figure
Taweret: a Python package for Bayesian model mixing
Uncertainty quantification using Bayesian methods is a growing area of
research. Bayesian model mixing (BMM) is a recent development which combines
the predictions from multiple models such that each model's best qualities are
preserved in the final result. Practical tools and analysis suites that
facilitate such methods are therefore needed. Taweret introduces BMM to
existing Bayesian uncertainty quantification efforts. Currently Taweret
contains three individual Bayesian model mixing techniques, each pertaining to
a different type of problem structure; we encourage the future inclusion of
user-developed mixing methods. Taweret's first use case is in nuclear physics,
but the package has been structured such that it should be adaptable to any
research engaged in model comparison or model mixing.Comment: 7 pages, 2 figures, submitted to JOSS (Journal of Open Source
Software) on 31 October 2023. Comments are welcome
Evolution of charm-meson ratios in an expanding hadron gas
We study the time evolution of the numbers of charm mesons after the kinetic
freeze-out of the hadron gas produced by a central heavy-ion collision. The
reaction rates have -channel singularities that
give contributions inversely proportional to the thermal width of the . The
ratio of the and production rates can differ significantly from
those predicted using the measured branching fractions.Comment: 7 pages, 1 figur