Nuclear Theory·nucl-th

Monday·April 4, 2022

6 papers—2 primary·4 cross-listed

03
[Submitted on 31 Mar 2022] (cross-list from hep-ph)
Thermodynamic approach to proton number fluctuations in baryon-rich heavy-ion matter created at moderate collision energies
Volodymyr Vovchenko🇺🇸 · Volker Koch🇺🇸
We develop a framework to relate proton number cumulants measured in heavy-ion collisions within a momentum space acceptance to the susceptibilities of baryon number, assuming that particles are emitted from a fireball with uniform distribution of temperature and baryochemical potential, superimposed on a hydrodynamic flow velocity profile. The rapidity acceptance dependence of proton cumulants measured by the HADES Collaboration in $s_{NN} = 2.4$ GeV Au-Au appears to be consistent with thermal emission of nucleons from a grand-canonical heat bath, with the extracted baryon number susceptibilities exhibiting an hierarchy $χ_{4}^{B} ≫ - χ_{3}^{B} ≫ χ_{2}^{B} ≫ χ_{1}^{B}$ . Naively, this could indicate large non-Gaussian fluctuations that might point to the presence of the QCD critical point close to the chemical freeze-out at $T \sim 70$ MeV and $μ_{B} \sim 850 - 900$ MeV. However, the description of the experimental data at large rapidity acceptances becomes challenging once the effect of exact baryon number conservation is incorporated, suggesting that more theoretical and experimental studies are needed to reach a firm conclusion.
Comments:
7 pages, 1 figure. v3: typos corrected, version published in Physics Letters B
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2204.00137 [pdf]
PLB(2022)·10 citations
04
[Submitted on 1 Apr 2022] (cross-list from hep-ph)
Net-proton number cumulant ratios as function of beam energy from an expanding nonequilibrium chiral fluid
Christoph Herold🇹🇭 · Ayut Limphirat🇹🇭 · Poramin Saikham🇹🇭 · Marlene Nahrgang🇫🇷 · Tom Reichert🇩🇪 · Marcus Bleicher🇩🇪
The beam energy scan program at RHIC provides data on net-proton number fluctuations with the goal to detect the QCD critical end point and first-order phase transition. Interpreting these experimental signals requires a vital understanding of the interplay of critical phenomena and the nonequilibrium dynamics of the rapidly expanding fireball. We study these aspects with a fluid dynamic expansion coupled to the explicit propagation of the chiral order parameter sigma via a Langevin equation. Assuming a sigma-proton coupling through an effective proton mass, we relate cumulants of the order parameter and the net-proton number at freeze-out and obtain observable cumulant ratios as a function of beam energy. We emphasize the role of the nonequilibrium first-order phase transition where a mixed phase with gradual freeze-out can significantly alter the cumulants. We find that the presence of a critical end point is clearly visible in the cumulant ratios for a relatively wide range of center-of-mass energies.
Comments:
7 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2204.00286 [pdf]
PRC(2022)·3 citations
05
[Submitted on 1 Apr 2022] (cross-list from physics.med-ph)
The innovative $^{52 g}$ Mn for PET imaging: production cross section modeling and dosimetric evaluation
F. Barbaro · L. Canton · M.P. Carante · A. Colombi · L. De Nardo · A. Fontana · L. Meléndez-Alafort
Background: Recently, the reaction $^{na t}$ V( $α$ ,x) $^{52 g}$ Mn has been proposed as a possible alternative to the standard $^{na t}$ Cr( $p$ ,x) $^{52 g}$ Mn one, but improvements in the modeling were needed to better compare the two production routes. Purpose: This work focuses on the development of precise simulations and models to compare the $^{52 g}$ Mn production from both reactions in terms of amount of activity and radionuclidic purity (RNP), as well as in terms of dose increase (DI) due to the co-produced radioactive contaminants, with respect to a pure $^{52 g}$ MnCl $_{2}$ injection. Methods: The nuclear code Talys has been employed to optimize the $^{na t}$ V( $α$ ,x) $^{52 g}$ Mn cross section by tuning the parameters of the microscopic level densities. Dosimetric assessments of [ $^{xx}$ Mn]Cl $_{2}$ have been accomplished with OLINDA software 2.2.0 using female and male phantoms. At the end, the yield of $^{xx}$ Mn radioisotopes estimated for the two production routes have been combined with the dosimetric results, to assess the DI at different times after the end of the irradiation. Results: Good agreement was obtained between cross sections calculations and measurements. The comparison of the two reaction channels suggests that $^{na t}$ V( $α$ ,x) $^{52 g}$ Mn leads to higher yield and higher purity, resulting in a less harmful impact on patients' health in terms of DI. Conclusions: Both $^{na t}$ V( $α$ ,x) and $^{na t}$ Cr( $p$ ,x) production routes provide clinically acceptable $^{52 g}$ MnCl $_{2}$ for PET imaging. However, the $^{na t}$ V( $α$ ,x) $^{52 g}$ Mn reaction provides a DI systematically lower than the one obtainable with $^{na t}$ Cr( $p$ ,x) $^{52 g}$ Mn and a longer time window in which it can be used clinically (RNP $\geq$ 99\%).
Comments:
19 pages, 5 figures, 6 tables
Subjects:
physics.med-ph (physics.med-ph); Nuclear Theory (nucl-th)
arXiv:
2204.00402 [pdf]
Med.Phys.(2023)·0 citations
06
[Submitted on 1 Apr 2022] (cross-list from hep-ph)
Complementarity of experimental and lattice QCD data on pion parton distributions
P. C. Barry🇺🇸 · C. Egerer🇺🇸 · J. Karpie🇺🇸 · W. Melnitchouk🇺🇸 · C. Monahan🇺🇸 · K. Orginos🇺🇸 · Jian-Wei Qiu🇺🇸 · D. Richards🇺🇸 · N. Sato🇺🇸 · R. S. Sufian🇺🇸 · S. Zafeiropoulos🇫🇷
We extract pion parton distribution functions (PDFs) in a Monte Carlo global QCD analysis of experimental data together with reduced Ioffe time pseudo-distributions and matrix elements of current-current correlators generated from lattice QCD. By including both experimental and lattice QCD data, our analysis rigorously quantifies both the uncertainties of the pion PDFs and systematic effects intrinsic to the lattice QCD observables. The reduced Ioffe time pseudo-distributions significantly decrease the uncertainties on the PDFs, while the current-current correlators are limited by the systematic effects associated with the lattice. Consistent with recent phenomenological determinations, the behavior of the valence quark distribution of the pion at large momentum fraction is found to be $\sim (1 - x)^{β_{eff}}$ with $β_{eff} \approx 1.0 - 1.2$ .
Comments:
47 pages, 15 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2204.00543 [pdf]
PRD(2022)·48 citations

Affiliations

first authorsco-authorsvia INSPIRE

Thermodynamic approach to proton number fluctuations in baryon-rich heavy-ion matter created at moderate collision energies

Net-proton number cumulant ratios as function of beam energy from an expanding nonequilibrium chiral fluid

The innovative 52gMn for PET imaging: production cross section modeling and dosimetric evaluation

Complementarity of experimental and lattice QCD data on pion parton distributions

Affiliations

The innovative $^{52 g}$ Mn for PET imaging: production cross section modeling and dosimetric evaluation