Nuclear Theory·nucl-th

Tuesday·November 3, 2020

16 papers—8 primary·8 cross-listed

01
A study of nuclear radii and neutron skin thickness of neutron-rich nuclei near the neutron drip line
Usuf Rahaman · M.Ikram · M. Imran · Anisul Ain Usmani
We studied the charge radius ( $r_{c}$ ), neutron radius ( $r_{n}$ ), and neutron skin-thickness ( $Δ r = r_{n} - r_{p}$ ) over a chain of isotopes from C to Zr with the stable region to the neutron drip line. Theoretical calculations are done with axially deformed self-consistent relativistic mean-field theory (RMF) with effective nonlinear NL3 and NL3* interactions. The theoretically estimated values are compared with available experimental data and a reasonable agreement are noted. We additionally assessed the two-neutron separation energy ( $S_{2 n}$ ) to mark the drip line nuclei of the considered isotopic series. In the reference of $S_{2 n}$ , neutron magicity is also discussed. The calculated neutron radii are compared with empirical estimation made by $r = r_{0} N^{1/3}$ to examine the abnormal trend of the radius for neutron drip line nuclei. In view to guide the long tails, the density distribution for some skin candidates is analyzed. Finally, neutron skin thickness is observed for the whole considered isotopic series.
nucl-thIJMPE(2020)·4 citations
02
Effect of quantizing magnetic field on the inner crusts of hot Neutron Stars
Rana Nandi · Somnath Mukhopadhyay · Sarmistha Banik
In the present work we study the effects of strongly quantizing magnetic fields and finite temperature on the properties of inner crusts of hot neutron stars. The inner crust of a neutron star contains neutron-rich nuclei arranged in a lattice and embedded in gases of free neutrons and electrons. We describe the system within the Wigner-Seitz (WS) cell approximation. The nuclear energy is calculated using Skyrme model with SkM* interaction. To isolate the properties of nuclei we follow the subtraction procedure presented by Bonche, Levit and Vautherin, within the Thomas-Fermi approximation. We obtain the equilibrium properties of inner crust for various density, temperatures and magnetic fields by minimizing the free energy of the WS cell satisfying the charge neutrality and $β -$ equilibrium conditions. We infer that at a fixed baryon density and temperature, strong quantizing magnetic field reduces the cell radii, neutron and proton numbers in the cell compared with the field free case. However, the nucleon number in the nucleus increases in presence of magnetic field. The free energy per nucleon also decreases in magnetized inner crust. On the other hand, we find that finite temperature tends to smear out the effects of magnetic field. Our results can be important in the context of $r -$ process nucleosynthesis in the binary neutron star mergers.
nucl-thastro-ph.HEPRC(2021)·2 citations
03
Multiplicity-dependent saturation momentum in $p$ -Pb collisions at 5.02 TeV
Takeshi Osada🇯🇵
Semi-inclusive transverse momentum spectra observed in proton-proton and proton-lead nuclear collisions at LHC energies obey a geometric scaling with a scaling variable using multiplicity-dependent saturation momentum. The saturation momentum extracted from the experimental data is proportional to the 1/6 power of the hadron multiplicity in the final state. On the other hand, the system's transverse size is proportional to the 1/3 power of the multiplicity, and the saturation momentum and the transverse size of the system are strongly correlated with the hadron multiplicity in the final state. Since the saturation momentum is proportional to the average transverse momentum of hadrons, one predicts average transverse momentum is also proportional to the 1/6 power of the multiplicity, which is consistent with experimental results at the LHC energy. We found that a nuclear modification factor $R_{pPb}$ calculated by the multiplicity-dependent saturation momentum decreases at $p_{T} ≲$ 1GeV/ $c$ and that our model can partially explain the $R_{pPb}$ 's behavior thought to be caused by nuclear shadowing. On the other hand, Cronin enhancement experimentally observed at $2 ≲ p_{T} ≲$ 6 GeV/ $c$ is not reproduced. However, the experimental result, including the Cronin effect, can be reproduced well by introducing $p_{T}$ dependence as a 4 $\sim$ 5\% correction to the multiplicity-dependent saturation momentum.We also discuss a relation between the geometric scaling in the semi-inclusive distributions and the string percolation model.
nucl-thhep-phPRC(2021)·5 citations
04
Low-energy dipole excitation mode in $^{18}$ O with antisymmetrized molecular dynamics
Yuki Shikata · Yoshiko Kanada-En'yo
Low-energy dipole (LED) excitations in $^{18}$ O were investigated using a combination of the variation after $K$ -projection in the framework of antisymmetrized molecular dynamics with $β$ -constraint with the generator coordinate method. We obtained two LED states, namely, the $1_{1}^{-}$ state with a dominant shell-model structure and the $1_{2}^{-}$ state with a large $^{14} C + α$ cluster component. Both these states had significant toroidal dipole (TD) and compressive dipole (CD) strengths, indicating that the TD and CD modes are not separated but mixed in the LED excitations of $^{18}$ O. This is unlike the CD and TD modes for well-deformed nuclei such as $^{10}$ Be, where the CD and TD modes are generated as $K^{π} = 0^{-}$ and $K^{π} = 1^{-}$ excitations, respectively, in a largely deformed state.
nucl-thPRC(2021)·3 citations
05
Light quark energy loss in a soft-wall AdS/QCD model
Xiangrong Zhu🇨🇳 · Zi-qiang Zhang🇨🇳
We investigate the energy loss of light quarks in a holographic QCD model with conformal invariance broken by a background dilaton. We perform the analysis within falling string and shooting string, respectively. It turns out that the two methods give the same result: the presence of chemical potential and confining scale tends to enhance the energy loss, in accord with previous findings of drag force and jet quenching parameter.
nucl-thEPJA(2021)·8 citations
06
An effective field theory approach to fermionic rotational bands in nuclei
I. K. Alnamlah · E. A. Coello Pérez · D. R. Phillips
We extend an effective field theory developed to describe rotational bands in even-even nuclei to the odd-mass case. This organizes Bohr and Mottelson's treatment of a particle coupled to a rotor as a model-independent expansion in powers of the angular velocity of the overall system. We carry out this expansion up to fourth order in the angular velocity and present results for $^{99}$ Tc, $^{159}$ Dy, $^{167, 169}$ Er, $^{167, 169}$ Tm, $^{183}$ W, $^{235}$ U and $^{239}$ Pu. In each case, the accuracy and breakdown scale of the effective field theory can be understood based on the single-particle and vibrational energy scales in that nucleus.
nucl-thnucl-exPRC(2021)·11 citations
07
$α$ -nucleus optical potentials from chiral effective field theory $N N$ interactions
V. Durant · P. Capel
We present a determination of optical potentials for $^{4}$ He-target collisions using the double-folding method. We use chiral effective field theory nucleon-nucleon interactions at next-to-next-to-leading order combined with state-of-the-art nucleonic densities. The imaginary part of the optical potential is obtained from the real double-folding interaction either through a proportionality constant or applying Kramers-Kronig dispersion relations. With these potentials, we compute the elastic scattering of $^{4}$ He off various targets, from $^{4}$ He to $^{120}$ Sn. We study the sensitivity of our predicted cross sections to the choice of nucleon-nucleon interactions and nuclear densities. Very good agreement is obtained with existing elastic-scattering data for $^{4}$ He energies between 100 and 400 MeV.
nucl-thPRC(2022)·6 citations
08
Decipher the $R_{Ψ_{m}}$ correlator in search for the chiral magnetic effect in relativistic heavy ion collisions
Yicheng Feng · Jie Zhao · Hao-jie Xu · Fuqiang Wang
Background: The chiral magnetic effect (CME) is extensively studied in heavy-ion collisions at RHIC and the LHC. An azimuthal correlator called $R_{Ψ_{m}}$ was proposed to measure the CME. By observing the same $R_{Ψ_{2}}$ and $R_{Ψ_{3}}$ (convex) distributions from A Multi-Phase Transport (AMPT) model, by contrasting data and model as well as large and small systems and by event shape engineering (ESE), a recent preprint (arXiv:2006.04251v1) from STAR suggests that the $R_{Ψ_{m}}$ observable is sensitive to the CME signal and relatively insensitive to backgrounds, and their Au+Au data are inconsistent with known background contributions. Purpose: We examine those claims by studying the robustness of the $R_{Ψ_{m}}$ observable using AMPT as well as toy model simulations. We compare $R_{Ψ_{m}}$ to the more widely used $Δ γ$ azimuthal correlator to identify their commonalities and differences. Methods: We use AMPT to simulate Au+Au, p+Au, and d+Au collisions at $s_{N N} = 200 GeV$ , and study the responses of $R_{Ψ_{m}}$ to anisotropic flow backgrounds in the model. We also use a toy model to simulate resonance flow background and input CME signal to investigate their effects in $R_{Ψ_{2}}$ . Additionally we use the toy model to perform an ESE analysis to compare to STAR data as well as predict the degree of sensitivity of $R_{Ψ_{2}}$ to isobar collisions with the event statistics taken at RHIC. ...
nucl-thnucl-exPRC(2021)·7 citations
09
Deuteron Uncertainties in the Determination of Proton PDFs
Richard D. Ball🇬🇧 · Emanuele R. Nocera🇬🇧 · Rosalyn L. Pearson🇬🇧
We evaluate the uncertainties due to nuclear effects in global fits of proton parton distribution functions (PDFs) that utilise deep-inelastic scattering and Drell-Yan data on deuterium targets. To do this we use an iterative procedure to determine proton and deuteron PDFs simultaneously, each including the uncertainties in the other. We apply this procedure to determine the nuclear uncertainties in the SLAC, BCDMS, NMC and DYE866/NuSea fixed target deuteron data included in the NNPDF3.1 global fit. We show that the effect of the nuclear uncertainty on the proton PDFs is small, and that the increase in overall uncertainties is insignificant once we correct for nuclear effects.
↳ hep-phhep-exnucl-thEPJC(2021)·41 citations
10
Three related topics on the periodic tables of elements
Yoshiteru Maeno · Kouichi Hagino · Takehiko Ishiguro
A large variety of periodic tables of the chemical elements have been proposed. It was Mendeleev who proposed a periodic table based on the extensive periodic law and predicted a number of unknown elements at that time. The periodic table currently used worldwide is of a long form pioneered by Werner in 1905. As the first topic, we describe the work of Pfeiffer (1920), who refined Werner's work and rearranged the rare-earth elements in a separate table below the main table for convenience. Today's widely used periodic table essentially inherits Pfeiffer's arrangements. Although long-form tables more precisely represent electron orbitals around a nucleus, they lose some of the features of Mendeleev's short-form table to express similarities of chemical properties of elements when forming compounds. As the second topic, we compare various three-dimensional helical periodic tables that resolve some of the shortcomings of the long-form periodic tables in this respect. In particular, we explain how the 3D periodic table "Elementouch" (Maeno 2001), which combines the s- and p-blocks into one tube, can recover features of Mendeleev's periodic law. Finally we introduce a topic on the recently proposed nuclear periodic table based on the proton magic numbers (Hagino and Maeno 2020). Here, the nuclear shell structure leads to a new arrangement of the elements with the proton magic-number nuclei treated like noble-gas atoms. We show that the resulting alignments of the elements in both the atomic and nuclear periodic tables are common over about two thirds of the tables because of a fortuitous coincidence in their magic numbers.
↳ physics.chem-phnucl-th2 citations
11
Conserved charge fluctuations in the chiral limit
Mugdha Sarkar🇩🇪 · Olaf Kaczmarek🇩🇪 · Frithjof Karsch🇩🇪 · Anirban Lahiri🇩🇪 · Christian Schmidt🇩🇪
We study the signs of criticality in conserved charge fluctuations and related observables of finite temperature QCD at vanishing chemical potential, as we approach the chiral limit of two light quarks. Our calculations have been performed on gauge ensembles generated using Highly Improved Staggered Quark (HISQ) fermion action, with pion masses ranging from 140 MeV to 55 MeV.
↳ hep-lathep-phnucl-thActa Phys.Polon.Supp.(2021)·4 citations
12
QCD in the heavy dense regime: Large $N_{c}$ and quarkyonic matter
Owe Philipsen🇩🇪 · Jonas Scheunert🇩🇪
After combined character and hopping expansions and integration over the spatial gauge links, lattice QCD reduces to a three-dimensional $S U (3)$ Polyakov loop model with complicated interactions. A simple truncation of the effective theory is valid for heavy quarks on reasonably fine lattices and can be solved by linked cluster expansion in its effective couplings. This was used ealier to demonstrate the onset transition to baryon matter in the cold and dense regime. Repeating these studies for general $N_{c}$ , one finds that for large $N_{c}$ the onset transition becomes first-order, and the pressure scales as $p \sim N_{c}$ through three consecutive orders in the hoppoing expansion. These features are consistent with the formal definition of quarkyonic matter given in the literature. We discuss the implications for $N_{c} = 3$ and physical QCD.
↳ hep-lathep-phnucl-thActa Phys.Polon.Supp.(2021)·1 citation
13
Ruling out color transparency in quasi-elastic $^{12}$ C(e,e'p) up to $Q^{2}$ of 14.2 (GeV/c) $^{2}$
D. Bhetuwal🇺🇸 · J. Matter🇺🇸 · H. Szumila-Vance🇺🇸 · M. L. Kabir🇺🇸 · D. Dutta🇺🇸 · R. Ent🇺🇸 · D. Abrams🇺🇸 · Z. Ahmed🇨🇦 · B. Aljawrneh🇺🇸 · S. Alsalmi🇺🇸 · R. Ambrose🇨🇦 · D. Androic🇭🇷 and 78 other authors
Quasielastic $^{12}$ C $(e, e^{'} p)$ scattering was measured at space-like 4-momentum transfer squared $Q^{2}$ ~=~8, 9.4, 11.4, and 14.2 (GeV/c) $^{2}$ , the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no $Q^{2}$ dependence, up to proton momenta of 8.5~GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured $Q^{2}$ scales in exclusive $(e, e^{'} p)$ reactions. These results impose strict constraints on models of color transparency for protons.
↳ nucl-exhep-exnucl-thPRL(2021)·50 citations
14
Two-Meson Form Factors in Unitarized Chiral Perturbation Theory
Yu-Ji Shi🇩🇪 · Chien-Yeah Seng🇩🇪 · Feng-Kun Guo🇨🇳 · Bastian Kubis🇩🇪 · Ulf-G. Meißner🇩🇪 · Wei Wang🇨🇳
We present a comprehensive analysis of form factors for two light pseudoscalar mesons induced by scalar, vector, and tensor quark operators. The theoretical framework is based on a combination of unitarized chiral perturbation theory and dispersion relations. The low-energy constants in chiral perturbation theory are fixed by a global fit to the available data of the two-meson scattering phase shifts. Each form factor derived from unitarized chiral perturbation theory is improved by iteratively applying a dispersion relation. This study updates the existing results in the literature and explores those that have not been systematically studied previously, in particular the two-meson tensor form factors within unitarized chiral perturbation theory. We also discuss the applications of these form factors as mandatory inputs for low-energy phenomena, such as the semi-leptonic decays $B_{s} \to π^{+} π^{-} ℓ^{+} ℓ^{-}$ and the $τ$ lepton decay $τ \to π^{-} π^{0} ν_{τ}$ , in searches for physics beyond the Standard Model.
↳ hep-phhep-exnucl-thJHEP(2021)·20 citations
15
Lattice continuum-limit study of nucleon quasi-PDFs
Constantia Alexandrou🇨🇾 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Jeremy R. Green🇨🇭 · Kyriakos Hadjiyiannakou🇨🇾 · Karl Jansen🇩🇪 · Floriano Manigrasso🇨🇾 · Aurora Scapellato🇵🇱 · Fernanda Steffens🇩🇪
The quasi-PDF approach provides a path to computing parton distribution functions (PDFs) using lattice QCD. This approach requires matrix elements of a power-divergent operator in a nucleon at high momentum and one generically expects discretization effects starting at first order in the lattice spacing $a$ . Therefore, it is important to demonstrate that the continuum limit can be reliably taken and to understand the size and shape of lattice artifacts. In this work, we report a calculation of isovector unpolarized and helicity PDFs using lattice ensembles with $N_{f} = 2 + 1 + 1$ Wilson twisted mass fermions, a pion mass of approximately 370 MeV, and three different lattice spacings. Our results show a significant dependence on $a$ , and the continuum extrapolation produces a better agreement with phenomenology. The latter is particularly true for the antiquark distribution at small momentum fraction $x$ , where the extrapolation changes its sign.
↳ hep-lathep-phnucl-thPRD(2021)·71 citations
16
Solution to the hyperon puzzle using dark matter
Antonino Del Popolo🇮🇹 · Maksym Deliyergiyev🇵🇱 · Morgan Le Delliou🇨🇳
In this paper, we studied the ``hyperon puzzle", a problem that nevertheless the large number of studies is still an open problem. The solution of this issue requires one or more mechanisms that could eventually provide the additional repulsion needed to make the EoS stiffer and, therefore, the value of $M_{max, T}$ compatible with the current observational limits. In this paper we proposed that including dark matter (DM) admixed with ordinary matter in neutron stars (NSs), change the hydrostatic equilibrium and may explain the observed discrepancies, regardless to hyperon multi-body interactions, which seem to be unavoidable. We have studied how non-self-annihilating, and self-interacting, DM admixed with ordinary matter in NSs changes their inner structure, and discussed the mass-radius relations of such NSs. We considered DM particle masses of 1, 10, and 100 GeV, while taking into account a rich list of the DM interacting strengths, $y$ . By analyzing the multidimensional parameter space, including several quantities like: a. the DM interacting strength, b. the DM particle mass as well as the quantity of DM in its interior, and c. the DM fraction, $f_{D M}$ , we put constraints in the parameter space $f_{D M} - p_{DM}^{'} / p_{OM}^{'}$ . Our bounds are sensitive to the recently observed NSs total masses.
↳ gr-qcastro-ph.HEhep-phnucl-thPhys.Dark Univ.(2020)·26 citations

Affiliations

first authorsco-authorsvia INSPIRE