Nuclear Theory·nucl-th

Tuesday·October 3, 2023

11 papers—5 primary·6 cross-listed

01
Isoscalar Giant Monopole Resonance in Mo-100: TDHF calculations and ground state deformation
P. D Stevenson · Abhishek · Yue Shi
The isoscalar giant monopole resonance in molybdenum-100 has been measured in recent alpha scattering experiments and its strength function extracted. By performing time-dependent Hartree-Fock calculations with Skyrme effective interactions, we are able to reproduce the gross features of the observed strength. The details of the structure are found to be dependent on the ground state shape. We use a measure of fit to determine which ground state shape correlates with the observed strength and find evidence for triaxiality in this nucleus.
nucl-thNuovo Cim.C(2024)·0 citations
02
Contrasting Features of Parton Energy Loss in Heavy-ion Collisions at RHIC and the LHC
Thomas Marshall🇺🇸 · Philip Suh🇺🇸 · Gang Wang🇺🇸 · Huan Zhong Huang🇺🇸
Energetic quarks and gluons lose energy as they traverse the hot and dense medium created in high-energy heavy-ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). The nuclear modification factor ( $R_{AA}$ ) of leading particles quantifies parton energy loss in such collisions, with the particle spectrum in $p + p$ collisions as a reference. Previous $R_{AA}$ measurements at RHIC energies have revealed an approximately constant trend at high transverse momenta ( $p_{T}$ ), implying a scenario where parton energy loss, $Δ p_{T}$ , scales proportionally with $p_{T}$ , a feature naively expected from energy loss dynamics in elastic collisions. In this study, we investigate the LHC $R_{AA}$ measurements which exhibit a pronounced $p_{T}$ dependence of $R_{AA}$ for various particle species, and our analysis attributes this behavior to $Δ p_{T}$ being approximately proportional to $p_{T}$ . These distinct features are consistent with model calculations of dominant radiative energy loss dynamics at the LHC, in contrast to the dominance of collisional energy loss at RHIC. Additionally, the linear increase of fractional energy loss with medium density at different $p_{T}$ magnitudes affirms the previous empirical observation that the magnitude of the energy loss depends mostly on the initial entropy density, with no significant path-length dependence. Implications on the dynamical scenarios of parton energy loss and future experimental investigations will also be discussed.
nucl-thhep-exhep-phnucl-exCPC(2025)·2 citations
03
Determination of the moments of the proton charge density: is there a proton radius puzzle?
M. Atoui · M.B. Barbaro · M. Hoballah · C. Keyrouz · R. Kunne · M. Lassaut · D. Marchand · G. Quemener · E. Voutier
The charge radius of the proton can be determined using two different kinds of experiments: the spectroscopy technique, measuring the hyperfine structure of hydrogen atoms, and the scattering technique, deducing the radius from elastic lepton scattering off a proton target. These two methods lead to quite different results, a discrepancy known as the "proton radius puzzle ". To shed light on this problem, we have proposed a novel method for the determination of spatial moments from densities expressed in the momentum space. This method provides a direct access not only to the second order moment, directly related to the proton radius, but to all moments of any real order larger than -3. The method is applied to the global analysis of proton electric form factor experimental data from Rosenbluth separation and low- $Q^{2}$ experiments, paying specific attention to the evaluation of the systematic errors. Within this analysis, the integer order moments of the proton charge density are evaluated, the moment of second order leading to a new determination of the proton charge radius.
nucl-thhep-phnucl-exNucl.Theor.(2023)·1 citation
04
Shell-model study of $β^{+}$ /EC-decay half-lives for $Z = 21 - 30$ nuclei
Vikas Kumar · Praveen C. Srivastava
In the present work, we have reported $β^{+}$ /EC-decay half-lives for $Z = 21 - 30$ nuclei using large-scale shell-model. %and N $\leq$ A recent study shows that some proton-rich nuclei in this region belong to the island of inversion. We have performed calculations for these nuclei using KB3G effective interaction, while for Ni, Cu, and Zn nuclei we have used JUN45 effective interaction in the $f_{5/2} p g_{9/2}$ model space. The calculated quenching factors for $f p$ and $f_{5/2} p g_{9/2}$ space using KB3G and JUN45 effective interactions are also reported. Shell-model results of $β$ -decay half-lives, excitation energies, log $f t$ values, and branching fractions are discussed and compared with the available experimental data. We have obtained a reasonable agreement with the available data.
nucl-thnucl-exEPJA(2023)·5 citations
05
Electric dipole transitions in the relativistic quasiparticle random phase approximation at finite temperature
Amandeep Kaur · Esra Yüksel · Nils Paar
Finite temperature results in various effects on the properties of nuclear structure and excitations of relevance for nuclear processes in hot stellar environments. Here we introduce the self-consistent finite temperature relativistic quasiparticle random phase approximation (FT-RQRPA) based on relativistic energy density functional with point coupling interaction for describing the temperature effects in electric dipole (E1) transitions. We perform a study of E1 excitations in the temperature range $T =$ 0-2 MeV for the selected closed- and open-shell nuclei ranging from $^{40}$ Ca to $^{60}$ Ca and $^{100}$ Sn to $^{140}$ Sn by including both thermal and pairing effects. The isovector giant dipole resonance strength is slightly modified for the considered range of temperature, while new low-energy peaks emerge for $E <$ 12 MeV with non-negligible strength in neutron-rich nuclei at high temperatures. The analysis of relevant two-quasiparticle configurations discloses how new excitation channels open due to thermal unblocking of states at finite temperature. The study also examines the isospin and temperature dependence of electric dipole polarizability ( $α_{D}$ ), resulting in systematic increase in the values of $α_{D}$ with increasing temperature, with a more pronounced effect observed in neutron-rich nuclei. The FT-RQRPA introduced in this work will open perspectives for microscopic calculation of $γ$ -ray strength functions at finite temperatures relevant for nuclear reaction studies.
nucl-thPRC(2024)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE

Isoscalar Giant Monopole Resonance in Mo-100: TDHF calculations and ground state deformation

Contrasting Features of Parton Energy Loss in Heavy-ion Collisions at RHIC and the LHC

Determination of the moments of the proton charge density: is there a proton radius puzzle?

Shell-model study of β+/EC-decay half-lives for Z=21−30 nuclei

Electric dipole transitions in the relativistic quasiparticle random phase approximation at finite temperature

Affiliations

Shell-model study of $β^{+}$ /EC-decay half-lives for $Z = 21 - 30$ nuclei