Nuclear Theory·nucl-th

Tuesday·February 7, 2023

8 papers—4 primary·4 cross-listed

01
Shedding light on the pion production in heavy-ion collisions and application into the neutron star matter properties
Heng-Jin Liu🇨🇳 · Ban Zhang · Yuan-Qing Guo🇨🇳 · Hui-Gan Cheng🇨🇳 · Si-Na Wei🇨🇳 · Zhao-Qing Feng🇨🇳
Within the framework of the quantum molecular dynamics transport model, the pion production and constraint of the high-density symmetry energy in heavy-ion collisions near threshold energy have been thoroughly investigated. The energy conservation in the decay of resonances and reabsorption of pions as well as in the inelastic nucleon-nucleon and nucleon-resonance collisions are taken into account. The isospin diffusion in the low-density region (0.2 $ρ_{0}$ - 0.8 $ρ_{0}$ ) and high-density region (1.2 $ρ_{0}$ - 1.8 $ρ_{0}$ ) is investigated by analyzing the spectra of neutron/proton and $π^{-} / π^{+}$ ratios in the isotopic reactions of $^{132}$ Sn + $^{124}$ Sn and $^{108}$ Sn + $^{112}$ Sn at the incident energy of 270 MeV/nucleon, in which the symmetry energy manifests the opposite effect in the different density domain. The controversial conclusion of the $π^{-} / π^{+}$ ratio for constraining the high-density symmetry energy by different transport models with the FOPI data has been clarified. A soft symmetry energy with the slope parameter of $L (ρ_{0}) = 42 \pm 25$ MeV by using the standard error analysis within the range of $1 σ$ is obtained by analyzing the experimental data from the S $π$ RIT collaboration. The neutron stars with the maximal mass of 2 $M_{⊙}$ and radius of 11-13 km are obtained with the constrained symmetry energy.
nucl-th1 citation
02
Probing the jet transport coefficient of cold nuclear matter in electron-ion collisions
Peng Ru🇨🇳 · Zhong-Bo Kang🇺🇸 · Enke Wang🇨🇳 · Hongxi Xing🇨🇳 · Ben-Wei Zhang🇨🇳
We present a study of the nuclear-medium induced transverse momentum broadening of particle production in future electron-ion-collision~(EIC) experiments. By considering the multiple scattering between hard partons and cold nuclear medium within the higher-twist factorization framework in perturbative QCD, we calculate the transverse momentum broadening of single hadron production in semi-inclusive measurements, as well as the nuclear enhancement of the transverse momentum imbalance for di-hadron and heavy-meson pair productions. In particular, a kinematics dependent non-perturbative jet transport coefficient $q^= q^(x, Q^{2})$ extracted in a global analysis of the current data, together with its uncertainty determined with a Hessian method, are input into our calculations and are available for the community. Significant kinematic and color-state dependences of the nuclear induced broadening/imbalance are predicted. Our results indicate that the future EIC measurements are able to provide powerful constraints on the kinematic dependence of the transport coefficient $q^$ and thus greatly facilitate the jet tomography of cold nuclear medium.
nucl-thhep-exhep-phnucl-ex6 citations
03
Three- $α$ configurations of the second $J^{π} = 2^{+}$ state in $^{12}$ C
H. Moriya · W. Horiuchi · J. Casal · L. Fortunato
We investigate geometric configurations of $α$ ( $^{4}$ He nucleus) clusters in the second $J^{π} = 2^{+}$ state of $^{12}$ C, which has been discussed as a rotational band member of the second $0^{+}$ state, the Hoyle state. The ground and excited $0^{+}$ and $2^{+}$ states are described by a three- $α$ cluster model. The three-body Schrödinger equation with orthogonality conditions is accurately solved by the stochastic variational method with correlated Gaussian basis functions. To analyse the structure of these resonant states in a convenient form, we introduce a confining potential. The two-body density distributions together with the spectroscopic information clarify the structure of these states. We find that main configurations of both the second $0^{+}$ and $2^{+}$ states are acute-angled triangle shapes originating from the $^{8}$ Be( $0^{+}$ ) $+ α$ configuration. However, the $^{8}$ Be $+ α$ components in the second $2^{+}$ state become approximately 2/3 because the 8Be subsystem is hard to excite, indicating that the state is not an ideal rigid rotational band member of the Hoyle state.
nucl-thEPJA(2023)·3 citations
04
Nuclear and Hybrid Equations of State in Light of the Low-Mass Compact Star in HESS J1731-347
Liam Brodie🇺🇸 · Alexander Haber🇺🇸
We sample over $500$ relativistic mean-field theories constrained by chiral effective field theory and properties of isospin-symmetric nuclear matter and test them against known stellar structure constraints. This includes a recent mass and radius measurement of a compact object in supernova remnant HESS J1731-347, with an unusually low mass of $M = 0.7 7_{- 0.17}^{+ 0.20} M_{⊙}$ and a compact radius of $R = 10. 4_{- 0.78}^{+ 0.86}$ km. We show that none of the sampled nuclear models meet all constraints at the $68 %$ credibility level, but that hybrid equations of state with a quark matter inner core and nuclear outer core easily can. This indicates a tension between astrophysical constraints and low-energy nuclear theory.
nucl-thastro-ph.HEhep-phPRC(2023)·40 citations
05
Rescattering effects in nucleon-to-meson form factors and application to tau-lepton-induced proton decay
Andreas Crivellin🇨🇭 · Martin Hoferichter🇨🇭
Nucleon decays put extremely stringent bounds on baryon-number-violating interactions. However, in case the corresponding operators involve only $τ$ leptons, the direct two-body decays, e.g., $p \to π^{0} τ^{+}$ , are kinematically not allowed and nucleon decay can only proceed via an off-shell $τ$ , leading to $p \to π^{0} ℓ^{+} ν_{ℓ} ν ˉ_{τ}$ . To calculate such processes, the momentum dependence of the form factors for nucleon-to-meson transitions, which describe the hadronization of the underlying process at the quark level, is needed. In this work, we point out new isospin and Fierz relations among such proton-kaon matrix elements and calculate the momentum dependence of the nucleon-to-meson form factors from the universal final-state interactions in terms of pion-nucleon or kaon-nucleon scattering phase shifts. We use these results to derive novel limits on the Wilson coefficients of the baryon-number-violating dimension- $6$ operators involving a $τ$ lepton, which were previously unconstrained.
↳ hep-phhep-exhep-latnucl-thPLB(2023)·14 citations
06
Opportunities for Fundamental Physics Research with Radioactive Molecules
Gordon Arrowsmith-Kron🇺🇸 · Michail Athanasakis-Kaklamanakis🇨🇭 · Mia Au🇨🇭 · Jochen Ballof🇨🇭 · Robert Berger🇩🇪 · Anastasia Borschevsky🇳🇱 · Alexander A. Breier🇩🇪 · Fritz Buchinger🇨🇦 · Dmitry Budker🇩🇪 · Luke Caldwell🇺🇸 · Christopher Charles🇨🇦 · Nike Dattani and 50 other authors
Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas of fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances in the ability to create, cool, and control complex molecules down to the quantum level, along with recent and upcoming advances in radioactive species production at several facilities around the world, create a compelling opportunity to coordinate and combine these efforts to bring precision measurement and control to molecules containing extreme nuclei. In this manuscript, we review the scientific case for studying radioactive molecules, discuss recent atomic, molecular, nuclear, astrophysical, and chemical advances which provide the foundation for their study, describe the facilities where these species are and will be produced, and provide an outlook for the future of this nascent field.
↳ nucl-exnucl-thphysics.atom-phRept.Prog.Phys.(2024)·81 citations
07
Viscous QCD medium effects on the bottom quark transport coefficients
Adiba Shaikh🇮🇳 · Sadhana Dash🇮🇳 · Basanta K. Nandi🇮🇳
The bottom quark transport coefficients, i.e., drag and diffusion coefficients, have been studied for the collisional and soft gluon radiative processes within the viscous QCD medium. The thermal medium effects are incorporated using the effective fugacity quasiparticle model (EQPM). Both the shear and bulk viscous effects at leading order are embedded through the near-equilibrium distribution functions of the quark-gluon plasma (QGP) constituent quasiparticles. The transport coefficients' dependence on the bottom quark's initial momentum and QGP temperature has been investigated. The relative dominance of the radiative over the collisional process for the bottom quark seems to occur at a higher initial momentum compared to that of the charm quark. In contrast, the effect of the viscous corrections seems to be more for the charm quark.
↳ hep-phnucl-thEPJC(2023)·6 citations
08
Cross section measurement of the 144Sm(alpha,n)147Gd reaction for studying the alpha-nucleus optical potential at astrophysical energies
Gy. Gyürky · P. Mohr · A. Angyal · Z. Halász · G.G. Kiss · Zs. Mátyus · T.N. Szegedi · T. Szücs · Zs. Fülöp
Nuclear reactions involving alpha particles play an important role in various astrophysical processes such as the gamma-process of heavy element nucleosynthesis. The poorly known low-energy alpha-nucleus optical (AOMP) potential is a key parameter to estimate the rates of these reactions. The AOMP can be tested by measuring the cross section of alpha-scattering as well as alpha-induced reactions. Low energy elastic alpha-scattering on 144Sm has recently been measured with high precision. The aim of the present work was to complement that work by measuring the (a,n) cross sections on 144Sm at low energies. The experimental data shall be used to constrain the AOMP. From this potential the 144Sm(a,g)148Gd reaction rate can be derived with reduced uncertainties. The 144Sm(a,n)147Gd reaction was studied by bombarding Sm targets with alpha-beams provided by the cyclotron accelerator of Atomki. The cross section was determined using the activation method. The gamma-radiation following the decay of the 147Gd reaction product was measured with a HPGe detector. The experimental data are analyzed within the statistical model. The cross section was measured in the alpha-energy range between 13 and 20 MeV in 1 MeV steps, i.e., from close above the (a,n) threshold. The results were compared with statistical model calculations using various approaches and parametrizations for the AOMP, and excellent agreement was obtained for two recent potentials. However, these potentials cannot reproduce literature data for the 144Sm(a,g)148Gd reaction with the same accuracy. Constraints for the AOMP were derived from an analysis of the new 144Sm(a,n)147Gd data and literature data for 144Sm(a,g)148Gd. These constraints enable a determination of the reaction rate of the 144Sm(a,g)148Gd reaction with significantly reduced uncertainties of less than a factor of two.
↳ nucl-exastro-ph.SRnucl-thPRC(2023)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE