Nuclear Theory·nucl-th

Friday·January 22, 2021

7 papers—4 primary·3 cross-listed

01
Giant dipole resonance in Sm isotopes within TDHF method
Ait Ben Mennana Azzeddine🇲🇦 · Mostafa Oulne🇲🇦
In this work, we have studied the isovector giant dipole resonance (IVGDR) in even-even Sm isotopes within time-dependent Hartree-Fock (TDHF) with four Skyrme forces SLy6, SVbas, SLy5 and UNEDF1. The approach we have followed is somewhat similar to the one we did in our previous work in the region of Neodymium (Nd, Z=60) [\href{https://iopscience.iop.org/article/10.1088/1402-4896/ab73d8}{Physica Scripta (2020)}]. We have calculated the dipole strength of $^{128 - 164} Sm$ , and compared with the available experimental data. An overall agreement between them is obtained. The dipole strength in neutron-deficient $^{128 - 142} Sm$ and in neutron-rich $^{156 - 164} Sm$ isotopes are predicted. Shape phase transition as well as shape coexistence in Sm isotopes are also investigated in the light of IVGDR. In addition, the correlation between the quadrupole deformation parameter $β_{2}$ and the splitting $Δ E / E ˉ_{m}$ of the giant dipole resonance (GDR) spectra is studied. The results confirm that $Δ E / E ˉ_{m}$ is proportional to quadrupole deformation $β_{2}$
nucl-thEur.Phys.J.Plus(2021)·9 citations
02
Momentum dependent mean-fields of (anti)hyperons
T. Gaitanos🇬🇷 · A. Chorozidou🇬🇷
We investigate the in-medium properties of hyperons and anti-hyperons in the framework of the Non-Linear Derivative (NLD) model. We focus on the momentum dependence of in-medium strangeness optical potentials. The NLD model is based on the simplicity of the well-established Relativistic Mean-Field (RMF) approximation, but it incorporates an explicit momentum dependence on a field-theoretical level. The extension of the NLD model to the (anti)baryon-octet is formulated in the spirit of SU(6) and G-parity arguments. It is shown that with an appropriate choice of momentum cut-offs the $Λ$ , $Σ$ and $Ξ$ optical potentials are consistent with recent studies of the chiral effective field theory and Lattice-QCD calculations over a wide momentum region. In addition, we present NLD predictions for the in-medium momentum dependence of $Λ$ -, $Σ$ - and $Ξ$ -hyperons. This work is important for future experimental studies such as CBM, PANDA at the Facility for Antiproton and Ion Research (FAIR). It is relevant for nuclear astrophysics too.
nucl-thNPA(2021)·16 citations
03
Electric dipole polarizability in neutron-rich Sn isotopes as a probe of nuclear isovector properties
Zhengzheng Li · Yifei Niu · Wenhui Long
The determination of nuclear symmetry energy, and in particular, its density dependence, is a long-standing problem for nuclear physics community. Previous studies have found that the product of electric dipole polarizability $α_{D}$ and symmetry energy at saturation density $J$ has a strong linear correlation with $L$ , the slope parameter of symmetry energy. However, current uncertainty of $J$ hinders the precise constraint on $L$ . We investigate the correlations between electric dipole polarizability $α_{D}$ (or times symmetry energy at saturation density $J$ ) in Sn isotopes and the slope parameter of symmetry energy $L$ using the quasiparticle random-phase approximation based on Skyrme Hartree-Fock-Bogoliubov. A strong and model-independent linear correlation between $α_{D}$ and $L$ is found in neutron-rich Sn isotopes where pygmy dipole resonance (PDR) gives a considerable contribution to $α_{D}$ , attributed to the pairing correlations playing important roles through PDR. This newly discovered linear correlation would help one to constrain $L$ and neutron-skin thickness $Δ R_{np}$ stiffly if $α_{D}$ is measured with high resolution in neutron-rich nuclei. Besides, a linear correlation between $α_{D} J$ in a nucleus around $β$ -stability line and $α_{D}$ in a neutron-rich nucleus can be used to assess $α_{D}$ in neutron-rich nuclei.
nucl-thPRC(2021)·20 citations
04
In-medium $Δ (1232)$ potential, pion production in heavy-ion collisions and the symmetry energy
M.D. Cozma🇺🇸 · M.B.Tsang🇺🇸
Using the dcQMD transport model, the isoscalar and isovector in-medium potentials of the $Δ$ (1232) baryon are studied and information regarding their effective strength is obtained from a comparison to experimental pion production data in heavy-ion collisions below 800 MeV/nucleon impact energy. The best description is achieved for an isoscalar potential moderately more attractive than the nucleon optical potential and a rather small isoscalar relative effective mass m $_{Δ}^{*} \approx$ 0.45. For the isovector component only a constraint between the potential's strength at saturation and the isovector effective mass difference can be extracted, which depends on quantities such as the slope of the symmetry energy and the neutron-proton effective mass difference. These results are incompatible with the usual assumption, in transport models, that the $Δ$ (1232) and nucleon potentials are equal. The density dependence of symmetry energy can be studied using the high transverse momentum tail of pion multiplicity ratio spectra. Results are however correlated with the value of neutron-proton effective mass difference. This region of spectra is shown to be affected by uncertain model ingredients such as the pion potential or in-medium correction to inelastic scattering cross-sections at levels smaller than 10 $%$ . Extraction of precise constraints for the density dependence of symmetry energy above saturation will require experimental data for pion production in heavy-ion collisions below 800 MeV/nucleon impact energy and experimental values for the high transverse momentum tail of pion multiplicity ratio spectra accurate to better than 5 $%$ .
nucl-thEPJA(2021)·34 citations
05
On Mass and Matter
Craig D. Roberts🇨🇳
The visible Universe is largely characterised by a single mass-scale; namely, the proton mass, $m_{p}$ . Contemporary theory suggests that $m_{p}$ emerges as a consequence of gluon self-interactions, which are a defining characteristic of quantum chromodynamics (QCD), the theory of strong interactions in the Standard Model. However, the proton is not elementary. Its mass appears as a corollary of other, more basic emergent phenomena latent in the QCD Lagrangian, e.g. generation of nuclear-size gluon and quark mass-scales, and a unique effective charge that may describe QCD interactions at all accessible momentum scales. These remarks are explained herein; and focusing on the distribution amplitudes and functions of $π$ and $K$ mesons, promising paths for their empirical verification are elucidated. Connected therewith, in anticipation that production of $J / ψ$ -mesons using $π$ and $K$ beams can provide access to the gluon distributions in these pseudo-Nambu-Goldstone modes, predictions for all $π$ and $K$ distribution functions are provided at the scale $ζ = m_{J / ψ}$ .
↳ hep-phhep-exhep-latnucl-ex+1AAPPS Bull.(2021)·51 citations
06
Open charm mesons and Charmonia in magnetized strange hadronic matter
Amal Jahan C.S.🇮🇳 · Amruta Mishra🇮🇳
We investigate the in-medium masses of open charm mesons ( $D$ ( $D^{0}$ , $D^{+}$ ), $D ˉ$ ( $D^{0} ˉ$ , $D^{-}$ ), $D_{s}$ ( $D_{s}^{+}$ , $D_{s}^{-}$ )) and charmonium states ( $J / ψ$ , $ψ (3686)$ , $ψ (3770)$ , $χ_{c 0}$ , $χ_{c 2}$ ) in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective model. In the presence of the magnetic field, the number density and scalar density of charged baryons have contributions from Landau energy levels. The mass modifications of open charm mesons arise due to their interactions with nucleons, hyperons, and the scalar fields (the non-strange field $σ$ , strange field $ζ$ and isovector field $δ$ ) in the presence of the magnetic field. The mass modifications of the charmonium states arise from the variation of dilaton field ( $χ$ ) in the magnetized medium, which simulates the gluon condensates of QCD. The in-medium mass of open charm mesons and charmonia are observed to decrease with an increase in baryon density, whereas the charged $D^{+}$ , $D^{-}$ , $D_{s}^{+}$ and $D_{s}^{-}$ mesons have additional positive mass shifts due to Landau quantization in the presence of the magnetic field. The effects of strangeness fraction are found to be more dominant for the $D ˉ$ mesons as compared to the $D$ mesons. The mass shifts of charmonia are observed to be larger in hyperonic medium compared to the nuclear medium.
↳ hep-phnucl-thCPC(2022)·10 citations
07
Photoproduction of $Λ^{*}$ and $Σ^{*}$ resonances with $J^{P} = 1/ 2^{-}$ off the proton
Sang-Ho Kim🇰🇷 · K. P. Khemchandani🇧🇷 · A. Martinez Torres🇧🇷 · Seung-il Nam🇰🇷 · Atsushi Hosaka🇯🇵
We study the photoproduction of the $Λ (1405)$ and $Σ (1400)$ hyperon resonances, the latter of which is not a well established state. We evaluate the $s$ -, $t$ - and $u$ -channel diagrams in the Born approximation by employing the effective Lagrangians. A new ingredient is the inclusion of a nucleon resonance $N^{*} (1895)$ that is dynamically generated with predictions for its coupling to the $K Λ (1405)$ and $K Σ (1400)$ channels. To extend the applicability of the model to energies beyond the threshold region, we consider a Regge model for the $t$ -channel $K$ - and $K^{*}$ -exchanges. Our results are in good agreement with the CLAS data available on $Λ (1405)$ , while for $Σ (1400)$ we predict observables for its production. We also provide polarization observables for both hyperon productions, which can be useful in future experimental investigations. The present study provides new information on the nucleon resonance $N^{*} (1895)$ which can be an alternative source for generating the hyperon resonances $Λ (1405)$ and $Σ (1400)$ .
↳ hep-phhep-exnucl-thPRD(2021)·24 citations

Affiliations

first authorsco-authorsvia INSPIRE

Giant dipole resonance in Sm isotopes within TDHF method

Momentum dependent mean-fields of (anti)hyperons

Electric dipole polarizability in neutron-rich Sn isotopes as a probe of nuclear isovector properties

In-medium Δ(1232) potential, pion production in heavy-ion collisions and the symmetry energy

On Mass and Matter

Open charm mesons and Charmonia in magnetized strange hadronic matter

Photoproduction of Λ∗ and Σ∗ resonances with JP=1/2− off the proton

Affiliations

In-medium $Δ (1232)$ potential, pion production in heavy-ion collisions and the symmetry energy

Photoproduction of $Λ^{}$ and $Σ^{}$ resonances with $J^{P} = 1/ 2^{-}$ off the proton