Nuclear Theory·nucl-th

Monday·April 4, 2022

6 papers—2 primary·4 cross-listed

01
Production and anisotropic flow of thermal photons in collision of $α$ -clustered carbon with heavy nuclei at relativistic energies
Pingal Dasgupta🇨🇳 · Rupa Chatterjee🇮🇳 · Guo-Liang Ma🇨🇳
The presence of $α$ -clustered structure in the light nuclei produces different exotic shapes in nuclear structure studies at low energies. Recent phenomenological studies suggest that collision of heavy nuclei with $α$ -clustered carbon ( $^{12}$ C) at relativistic energies can lead to large initial state anisotropies. This is expected to impact the final momentum anisotropies of the produced particles significantly. The emission of electromagnetic radiations is considered to be more sensitive to the initial state compared to hadronic observables and thus photon observables are expected to be affected by the initial clustered structure profoundly. In this work we estimate the production and anisotropic flow of photons from most-central collisions of triangular $α$ -clustered carbon and gold at $s_{NN} = 200$ GeV using an event-by-event hydrodynamic framework and compare the results with those obtained from unclustered carbon and gold collisions. We show that the thermal photon $v_{3}$ for most central collisions is significantly large for the clustered case compared to the case with unclustered carbon, whereas the elliptic flow parameter does not show much difference for the two cases. In addition, the ratio of anisotropic flow coefficients is found to be a potential observable to constrain the initial state produced in relativistic heavy-ion collisions and also to know more about the $α$ -clustered structure in carbon nucleus.
nucl-thhep-phnucl-exPRC(2023)·10 citations
02
Zero-temperature thermodynamics of dense asymmetric strong-interaction matter
Jens Braun🇩🇪 · Benedikt Schallmo🇩🇪
Employing constraints derived from the microscopic theory of the strong interaction, we estimate the zero-temperature phase structure of dense isospin-asymmetric matter with two quark flavors. We find indications that strong-interaction matter along trajectories relevant for astrophysical applications undergoes a first-order phase transition from a color-superconducting phase to an ungapped quark-matter phase when the density is increased. Such a phase transition is found to be absent in isospin-symmetric matter. Moreover, by taking into account constraints from $β$ -equilibrium, charge neutrality, and color neutrality, we provide an estimate for the speed of sound in neutron-star matter. Notably, we observe that the speed of sound in neutron-star matter exceeds the asymptotic value associated with the noninteracting quark gas and even increases towards lower densities across a wide range, in agreement with recent results for isospin-symmetric matter. Considering results from studies based on chiral effective field theory at low densities, our findings suggest the existence of a maximum in the speed of sound for $n / n_{0} ≲ 10$ , where $n_{0}$ is the nuclear saturation density.
nucl-thhep-phPRD(2022)·37 citations
03
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.
↳ hep-phnucl-exnucl-thPLB(2022)·10 citations
04
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.
↳ hep-phnucl-thPRC(2022)·3 citations
05
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\%).
↳ physics.med-phnucl-thMed.Phys.(2023)·0 citations
06
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 $β_{eff} \approx 1.0 - 1.2$ .
↳ hep-phhep-exhep-latnucl-thPRD(2022)·48 citations

Affiliations

first authorsco-authorsvia INSPIRE

Production and anisotropic flow of thermal photons in collision of α-clustered carbon with heavy nuclei at relativistic energies

Zero-temperature thermodynamics of dense asymmetric strong-interaction matter

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

Production and anisotropic flow of thermal photons in collision of $α$ -clustered carbon with heavy nuclei at relativistic energies

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