Nuclear Theory·nucl-th

Wednesday·September 13, 2023

11 papers—5 primary·6 cross-listed

06
Magnetic and density effects on the nucleon axial coupling
C. A. Dominguez🇿🇦 · M. Loewe🇿🇦 · C. Villavicencio🇨🇱 · R. Zamora🇨🇱
Using appropriate QCD finite energy sum rules, we discuss the influence of an external magnetic field and baryonic density on the axial-vector coupling constant $g_{A}$ . This scenario corresponds to a magnetar environment. We found that $g_{A}$ decreases both as function of the magnetic field strength and the baryonic density. It turns out that at the nuclear density $ρ_{0}$ the axial-vector coupling takes the value $g_{A}^{*} \approx 0.92$ . Although $g_{A}$ decreases in general with the magnetic field intensity, $g_{A}^{*}$ does not change in a relevant way with the magnetic field.
↳ hep-phnucl-th1 citation
07
Impact of modified gravity theory on neutron star and nuclear matter properties
Naosad Alam🇮🇳 · Subrata Pal🇮🇳 · A. Rahmansyah🇮🇩 · A. Sulaksono🇮🇩
New observational data, measured with a high degree of accuracy, of compact isolated neutron stars and binary stars in gravitational wave remnants have the potential to explore the strong field gravity. Within the framework of energy-momentum squared gravity (EMSG) theory we study its impact on several properties of neutron stars and plausible modifications from the predictions of general relativity. Based on a representative set of relativistic nuclear mean field models, non-relativistic Skyrme-Hartree-Fock models and microscopic calculations, we show deviations of neutron star mass-radius sequence in EMSG theory as compared to general relativity. The variation in the effective nuclear equation of state in EMSG, results in distinct magnitudes in the reduced pressure, speed of sound, and maximum compactness at the center of neutron stars. We perform extensive correlation analysis of the nuclear model parameters with the neutron star observables in light of the new observational bounds. Perceptible modifications in the correlations are found in the models of gravity that provide different estimates of the slope and curvature of nuclear matter symmetry energy. The available neutron star data however do not impose stringent enough constraints for clear evidence of deviations from general relativity.
↳ gr-qcnucl-thPRD(2024)·19 citations
08
Neutrinos and Heavy Element Nucleosynthesis
Xilu Wang · Rebecca Surman
This chapter discusses three nucleosynthesis processes involved in producing heavy nuclei beyond the iron group that are influenced or shaped by neutrino interactions: the v process, the vp process and the r process. These processes are all related to explosive events involving compact objects, such as core-collapse supernovae and binary neutron star mergers, where an abundant amount of neutrinos are emitted. The interactions of the neutrinos with nucleons and nuclei through both charged-current and neutral-current reactions play a crucial role in the nucleosynthesis processes. During the propagation of neutrinos inside the nucleosynthesis sites, neutrinos may undergo flavor oscillations that can also potentially affect the nucleosynthesis yields. Here we provide a general overview of the possible effects of neutrinos and neutrino flavor conversions on these three heavy-element nucleosynthesis processes.
↳ astro-ph.HEhep-phnucl-thIn: Tanihata, I., Toki, H., Kajino, T. (e…·8 citations
09
Exploring Anisotropic flow via the Boltzmann Transport Equation Employing the Tsallis Blast Wave Description at LHC energies
Aviral Akhil🇮🇳 · Swatantra Kumar Tiwari🇮🇳
Anisotropic flows $i . e .$ azimuthal anisotropies in particle production are one of the important probes in characterizing the properties of the strongly interacting matter created in the relativistic heavy-ion collisions. These observables are sensitive to both the transport properties as well as the equation of state (EOS) of Quantum Chromodynamics (QCD) matter. We have adopted the Boltzmann transport equation (BTE) in the relaxation time approximation (RTA) to describe the experimental data for harmonic flows such as elliptic flow ( $v_{2}$ ), triangular flow ( $v_{3}$ ), quadrangular flow ( $v_{4}$ ) obtained in heavy-ion collisions at Large Hadron Collider (LHC) energies. In this analysis, we have used Tsallis statistics as an initial distribution and the Tsallis Blast wave (TBW) description is used as the equilibrium distribution function while describing the evolution of the particle production in BTE. We have fitted the transverse momentum spectra, $v_{2}$ , $v_{3}$ , and $v_{4}$ of identified hadrons such as pion, kaon, and proton for Pb-Pb and Xe-Xe collisions at the LHC energies of $s_{N N}$ = 5.02 TeV and $s_{N N}$ = 5.44 TeV, respectively for various centralities. Our study offers a comparative analysis between the two distinct collision systems operating at comparable collision energies. The present formulation successfully fits the experimental data for $p_{T}$ -spectra upto $p_{T}$ = 8 GeV and effectively explains the anisotropic flows data upto $p_{T}$ = 10 GeV with a very favourable $χ^{2} / n df$ . We observe that the average transverse flow velocity ( $< β_{r} >$ ) and the kinetic freeze-out temperature ( $T$ ) extracted in our analysis decrease as we go towards the peripheral collisions. The azimuthal modulation amplitudes ( $ρ_{a}$ ) exhibit an increasing pattern as one moves from central to peripheral collisions in both the Pb-Pb and Xe-Xe nuclei interactions.
↳ hep-phnucl-thJ.Phys.G(2024)·12 citations
10
Assumption Breakdown in Radiative Energy Loss
Coleridge Faraday🇿🇦 · W. A. Horowitz🇿🇦
We show that an integral assumption in DGLV radiative energy loss - the large formation time assumption - is violated at high- $p_{T}$ for phenomenologically relevant parameters. We further investigate the phenomenological impact of placing a new kinematic bound on the radiated gluon transverse momentum, which ensures that there are no contributions to the energy loss from regions of parameter space that violate the large formation time assumption. We find that this places a large sensitivity on the exact kinematic cutoff used, similar to the known collinear cutoff sensitivity, indicating the theoretical need for a rederivation of DGLV radiative energy with the large formation time assumption relaxed in order to make rigorous predictions. We additionally find that this large formation time cutoff dramatically reduces the size of a short pathlength correction to the DGLV radiative energy loss, which is of phenomenological interest in predicting suppression in small $p + A$ systems. We compute the phenomenological predictions utilizing this large formation time cutoff in both $p + A$ and $A + A$ collisions at the LHC, in a convolved radiative and elastic energy loss model.
↳ hep-phnucl-th6 citations
11
155Tb production by cyclotrons: what level of 155Gd enrichment allows clinical applications?
Francesca Barbaro · Luciano Canton · Nikolay Uzunov · Laura De Nardo · Laura Melendez-Alafort
BACKGROUND: 155Tb represents a potentially useful radionuclide for diagnostic medical applications, but its production remains a challenging problem. A recent experimental campaign, conducted with low-energy proton beams impinging on a 155Gd target with 91.9% enrichment, demonstrated a significant co-production of 156gTb, a contaminant of great concern since its half-life is comparable to that of 155Tb and its high-energy gamma emissions severely impact on the dose released and on the quality of the SPECT images. Herein, the isotopic purity of the enriched 155Gd target necessary to minimize the co-production of contaminant radioisotopes, in particular 156gTb, was explored using various computational simulations. RESULTS: Starting from the recent data obtained with the 155Gd-enriched target, the co-production of other Tb radioisotopes besides 155Tb has been evaluated using the TALYS code. It was found that 156Gd, with an isotopic content of 5.87%, was the principal contributor to the co-production of 156gTb. The analysis also demonstrated that the maximum amount of 156Gd admissible for 155Tb production with a radionuclidic purity higher than 99% was 1%. A less stringent condition was obtained through computational dosimetry analysis, suggesting that a 2% content of 156Gd in the target can be tolerated to limit the dose increase to the patient below the 10% limit. Moreover, it has been demonstrated that the imaging properties of the produced 155Tb are not severely affected by this level of impurity in the target. CONCLUSIONS: 155Tb can be produced with a quality suitable for medical applications using low-energy proton beams and 155Gd-enriched targets if the 156Gd impurity content does not exceed 2%. Under these conditions, the dose increase due to the presence of contaminant radioisotopes remains below the 10% limit and good quality images, comparable to those of 111In, are guaranteed.
↳ physics.med-phnucl-exnucl-thEJNMMI Physics(2024)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Magnetic and density effects on the nucleon axial coupling

Impact of modified gravity theory on neutron star and nuclear matter properties

Neutrinos and Heavy Element Nucleosynthesis

Exploring Anisotropic flow via the Boltzmann Transport Equation Employing the Tsallis Blast Wave Description at LHC energies

Assumption Breakdown in Radiative Energy Loss

155Tb production by cyclotrons: what level of 155Gd enrichment allows clinical applications?

Affiliations