Nuclear Theory·nucl-th

Tuesday·September 29, 2020

18 papers—9 primary·9 cross-listed

01
[Submitted on 25 Sept 2020]
A Novel Regularization Scheme for Nucleon-Nucleon Lattice Simulations with Effective Field Theory
M. Ahmadi🇮🇷 · M. R. Hadizadeh🇺🇸 · M. Radin🇮🇷 · S. Bayegan🇮🇷
We propose a new regularization scheme to study the bound state of two-nucleon systems in Lattice Effective Field Theory. Inspired by continuum EFT calculation, we study an exponential regulator acting on the leading-order (LO) and next-to-leading order (NLO) interactions, consisting of local contact terms. By fitting the low-energy coefficients (LECs) to deuteron binding energy and the asymptotic normalization coefficient (ANC) on a lattice simulation, we extract the effective range expansion (ERE) parameters in the $^{3} S_{1}$ channel to order $p^{2}$ . We explore the impact of different powers of the regulator on the extracted ERE parameters for the lattice spacing $a = 1.97$ fm. Moreover, we investigate how the implementation of the regularization scheme improves the predicted ERE parameters on the lattice spacing in the range of $1.4 \leq a \leq 2.6$ fm. Our numerical analysis indicates that for lattice spacing greater than $2$ fm, the predicted observables are very close to the experimental data.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.12402 [pdf]
PRC(2020)·3 citations
02
[Submitted on 26 Sept 2020]
Impact-Parameter Description of High-Energy Deuteron-Nucleus Collisions
V. Franco · R.J. Glauber
A theoretical analysis using an impact-parameter description of the collisions of deuterons with nuclei is carried out in the high-energy diffraction approximation. It is used to obtain the intensities and integrated cross sections for elastic scattering, for the emergence of the two incident nucleons from the collision whether they appear as an elastically scattered deuteron or as two unbound nucleons, and for the diffraction-induced dissociation of the deuteron into a free neutron and a free proton, as well as the total cross section. The cross section for collisions in which one or both of the nucleons is absorbed is derived in terms of the sum of the neutron-nucleus and proton-nucleus effective phase shifts. Expressions for the cross section for processes in which the proton (or neutron) is absorbed whether the neutron (or proton) is absorbed or not, and for the cross section for processes in which the neutron (or proton) is absorbed and the proton (or neutron) remains free are derived. A reduced form of a two-particle density matrix is introduced to directly derive expressions for the cross section for two-particle absorption in which both the proton and neutron are absorbed and for the cross section for stripping processes in which the proton (or neutron) is absorbed and the neutron (or proton) emerges as a free particle. The expression for the cross section for the breakup of the deuteron and the resulting emergence of one or two free nucleons is also derived. The mechanism by which the diffraction dissociation of the deuteron is induced is understood in an approximate semi-quantitative basis in classical terms (primarily the radial derivative of the radial impulse), allowing an estimate of where in the nuclear potential (beyond the "radius", near the "surface") the dissociation process tends to predominantly occur.
Comments:
18 pages plus 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.12586 [pdf]
0 citations
03
[Submitted on 26 Sept 2020]
Effect of Inner Crust EoS on Neutron star properties
Ishfaq Ahmad Rather · Anisul Ain Usmani · Suresh Kumar Patra
The neutron star maximum mass and the radius are investigated within the framework of the relativistic mean-field (RMF) model. The variation in the radius at the canonical mass, $R_{1.4}$ , using different inner crust equation of state (EoS) with different symmetry energy slope parameter is studied. It is found that although the NS maximum mass and the corresponding radius do not vary much with different inner crust EoSs, the radius and the tidal deformability at 1.4 $M_{⊙}$ vary with the different choice of crust EoS and variation of about 1-2 km is seen in the radius at the canonical mass. For non-unified EoSs, the crust with a low symmetry energy slope parameter produces a low NS radius at the canonical mass. The properties of maximally rotating neutron stars are also studied. The variation in the radius of rotating star at the canonical mass 1.4 $M_{⊙}$ is also seen with the slope parameter. Similar to the static neutron star, the radius at 1.4 $M_{⊙}$ of rotating neutron star is affected by slope parameter of the inner crust. Other important quantities like moment of inertia, frequency, rotational kinetic energy to gravitational energy ratio are also calculated. The variation in these quantities with the crust slope parameter is found to be more proportional to the mass and the radius of NS.
Comments:
27 pages, 14 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2009.12613 [pdf]
NPA(2021)·25 citations
04
[Submitted on 26 Sept 2020]
Study of Cluster Structures in Nuclei through the Ratio Method. A Tribute to Mahir Hussein
Pierre Capel · Ronald C. Johnson · Filomena M. Nunes
For one-neutron halo nuclei, the cross section for elastic scattering and breakup at intermediate energy exhibit similar angular dependences. The Recoil Excitation and Breakup (REB) model of reactions elegantly explains this feature. It also leads to the idea of a new reaction observable to study the structure of loosely-bound nuclear systems: the Ratio. This observable consists of the ratio of angular distributions for different reaction channels, viz. elastic scattering and breakup, which cancels most of the dependence on the reaction mechanism; in particular it is insensitive to the choice of optical potentials that simulate the projectile-target interaction. This new observable is very sensitive to the structure of the projectile. In this article, we review the Ratio Method and its extension to low beam energies and proton-halo nuclei.
Comments:
Submitted to the European Physical Journal A as a contribution to the Special Issue on "Cluster structure and dynamics of nuclei" dedicated to the memory of Mahir S. Hussein (1944-2019). 12 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2009.12624 [pdf]
EPJA(2020)·5 citations
05
[Submitted on 27 Sept 2020]
Unified description of the coupled-channels and statistical Hauser-Feshbach nuclear reaction theories for low energy neutron incident reactions
Toshihiko Kawano
We incorporate the coupled-channels optical model into the statistical Hauser-Feshbach nuclear reaction theory, where the scattering matrix is diagonalized by performing the Engelbrecht-Weidenmüller transformation. This technique has been implemented in the coupled-channels optical model code ECIS by J. Raynal, and we extend this method so that all the open channels in a nucleon-induced reaction on a deformed nucleus can be calculated consistently.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.12736 [pdf]
EPJA(2021)·13 citations
06
[Submitted on 25 Sept 2020]
QCD phase diagram at finite isospin and baryon chemical potentials with the self-consistent mean field approximation
Zu-Qing Wu🇨🇳 · Jia-Lun Ping🇨🇳 · Hong-Shi Zong🇨🇳
The self-consistent mean field approximation of two-flavor NJL model with introducing a free parameter $α$ to reflect the competition between "direct" channel and the "exchange" channel, is employed to study QCD phase structure at finite isospin chemical potential $μ_{I}$ , finite baryon chemical potential $μ_{B}$ and finite temperature $T$ , especially the location of the QCD critical point. It is found that, for fixed isospin chemical potentials the lower temperature of phase transition is obtained with $α$ increasing in the $T - μ_{I}$ plane, and the largest difference of the phase transition temperature with different $α$ 's appears at $μ_{I} \sim 1.5 m_{π}$ . At $μ_{I} = 0$ the temperature of the QCD critical end point (CEP) decreases with $α$ increasing, while the critical baryon chemical potential increases. At high isospin chemical potential ( $μ_{I} = 500$ MeV), the temperature of the QCD tricritical point (TCP) increases with $α$ increasing, and in the regions of low temperature the system will transit from pion superfluidity phase to the normal phase as $μ_{B}$ increases. At low temperatures, the critical temperature of QCD phase transition with different $α$ 's rapidly increases with $μ_{I}$ at the beginning, and then increases smoothly around $μ_{I} > 300$ MeV. In high baryon density region, the increase of the isospin chemical potential will raise the critical baryon chemical potential of phase transition.
Comments:
7 pages, 9 figures. arXiv admin note: substantial text overlap with arXiv:2003.02988
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2009.13070 [pdf]
CPC(2021)·7 citations
07
[Submitted on 28 Sept 2020]
The origin of the spin-orbit and pseudospin-orbit splittings' evolution in neutron drop
Yinghui Ge · Ying Zhang · Jinniu Hu
We found the same staggering pattern in the evolution of the spin-orbit (SO) and pseudospin-orbit (PSO) splittings in neutron drops obtained by the energy-density functional (EDF) theory using SAMi-T and SLy5 parameterizations, with and without the tensor terms respectively. This staggering evolution is similar to the results recently obtained by the relativistic Brueckner-Hartree-Fock (RBHF) theory with Bonn A potential, which was claimed to be a tensor effect. In this work, we present an intuitive but essential explanation on the origin of this staggering evolution in the Skyrme EDF theory. We found that for both the SO and PSO partners, the energy splittings mainly originate from the SO potential. The staggering evolution of both the SO and PSO splittings is mainly due to the drastic change of density while neutrons filling different single-particle orbits. The key to determine the specific staggering pattern is the strength of the neutron density gradient term and the SO density term in the SO potential, not necessarily the tensor force.
Comments:
11 pages, 3 figures, 1 tables, accepted by Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.13193 [pdf]
PRC(2020)·2 citations
08
[Submitted on 28 Sept 2020]
Hyperon halo structure of C and B isotopes
Ying Zhang · Hiroyuki Sagawa🇯🇵 · Emiko Hiyama🇯🇵
We study the hypernuclei of C and B isotopes by Hartree-Fock model with Skyrme-type nucleon-nucleon and nucleon-hyperon interactions. The calculated $Λ$ binding energies agree well with the available experiment data. We found halo structure in the hyperon $1 p$ -state with extended wave function beyond nuclear surface in the light C and B isotopes. We also found the enhanced electric dipole transition between $1 p$ - and $1 s$ -hyperon states, which could be the evidence for this hyperon halo structure.
Comments:
16 pages, 2 figures, 3 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.13196 [pdf]
PRC(2021)·29 citations
09
[Submitted on 28 Sept 2020]
Phase diagram of alpha matter with Skyrme-like scalar interaction
Leonid M. Satarov🇩🇪 · Roman V. Poberezhnyuk🇩🇪 · Igor N. Mishustin🇩🇪 · Horst Stoecker🇩🇪
The equation of state and phase diagram of strongly interacting matter composed of $α$ particles are studied in the mean-field approximation. The particle interactions are included via a Skyrme-like mean field, containing both attractive and repulsive terms. The model parameters are found by fitting known values of binding energy and baryon density in the ground state of $α$ matter, obtained from microscopic calculations by Clark and Wang. Thermodynamic quantities of $α$ matter are calculated in the broad domains of temperature and baryon density, which can be reached in heavy-ion collisions at intermediate energies. The model predicts both first-order liquid-gas phase transition and Bose-Einstein condensation of $α$ particles. We present the profiles of scaled variance, sound velocity and isochoric heat capacity along the isentropic trajectories of $α$ matter. Strong density fluctuations are predicted in the vicinity of the critical point at temperature $T_{c} \approx 14 MeV$ and density $n_{c} \approx 0.012 fm^{- 3}$ .
Comments:
29 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2009.13487 [pdf]
PRC(2021)·14 citations
10
[Submitted on 26 Sept 2020] (cross-list from astro-ph.HE)
Constraining neutron superfluidity with $r$ -mode physics
Elena M. Kantor · Mikhail E. Gusakov · Vasiliy A. Dommes
We constrain the parameters of neutron superfluidity in the cores of neutron stars making use of the recently proposed effect of resonance stabilization of $r$ -modes. To this end, we, for the first time, calculate the finite-temperature $r$ -mode spectra for realistic models of rotating superfluid neutron stars, accounting for both muons and neutron-proton entrainment in their interiors. We find that the ordinary (normal) $r$ -mode exhibits avoided crossings with superfluid $r$ -modes at certain stellar temperatures and spin frequencies. Near the avoided crossings, the normal $r$ -mode dissipates strongly, which leads to substantial suppression of the $r$ -mode instability there. The extreme sensitivity of the positions of avoided crossings to the neutron superfluidity model allows us to constrain the latter by confronting the calculated spectra with observations of rapidly rotating neutron stars in low-mass X-ray binaries.
Comments:
6 pages, 4 figures, accepted for publication in Phys. Rev. Lett
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2009.12553 [pdf]
PRL(2020)·19 citations
11
[Submitted on 26 Sept 2020] (cross-list from hep-ph)
Associated production in pp and heavy ion collisions
Hua-Sheng Shao🇫🇷
Associated particle production processes in pp and heavy ion collisions at the LHC are in particular interesting in the sense that they provide unique tools to study double parton scattering (DPS) mechanism. In this talk, I will first review the recent theoretical, phenomenological and experimental developments of DPS in pp collisions. Then, I will focus on the DPS studies in heavy ion collisions, and stress their roles in understanding the cold nuclear matter effects, such as the (poorly known) impact-parameter dependent nuclear parton densities.
Comments:
4 pages, 1 figure, accepted contribution to proceedings of the 8th Annual Conference on Large Hadron Collider Physics (LHCP2020), 25-30 May, 2020, online
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2009.12555 [pdf]
PoS(2021)·1 citation
12
[Submitted on 26 Sept 2020] (cross-list from astro-ph.HE)
Bayesian inference of quark star equation of state using the NICER PSR J0030+0451 data
Ang Li🇨🇳 · Zhi-Qiang Miao🇨🇳 · Jin-Liang Jiang🇨🇳 · Shao-Peng Tang🇨🇳 · Ren-Xin Xu🇨🇳
We constrain the equation of state of quark stars within the Bayesian statistical approach using the mass and radius measurements of PSR J0030+0451 from NICER. Three types of bag models, with and without non-zero finite quark mass and/or superfluidity, are employed for quark stars made up with self-bound strange quark matter. We find the $90%$ posterior credible boundary around the most probable values of the quark star maximum mass is $M_{TOV} = 2.3 8_{- 0.23}^{+ 0.26} M_{⊙}$ , within the model flexibility of the finite quark mass, the quark pairing gap, and the perturbative contribution from the one-gluon exchange. The radius of a canonical $1.4 M_{⊙}$ quark star is $R_{1.4} \sim 12.3 km$ , smaller than the results based on neutron star models.
Comments:
7 pages, 4 figures, 3 tables; MNRAS in press. The analyses of quark star equation of state on the GW170817 and GW190425 data from LIGO/Virgo are reported in arXiv:2107.13997 (to appear in ApJL)
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2009.12571 [pdf]
MNRAS·33 citations
13
[Submitted on 27 Sept 2020] (cross-list from nucl-ex)
Multi-neutron transfer in $^{8}$ He induced reactions near the Coulomb barrier
I. Martel · N. Keeley · K.W. Kemper · K. Rusek
The measured inclusive $^{6}$ He and $^{4}$ He production cross sections of G. Marquínez-Durán {\em et al.}, Phys.\ Rev.\ C {\bf 98}, 034615 (2018) are reexamined and the conclusions concerning the relative importance of 1n and 2n transfer to the production of $^{6}$ He arising from the interaction of a 22 MeV $^{8}$ He beam with a $^{208}$ Pb target revised. A consideration of the kinematics of the 2n-stripping reaction when compared with the measured $^{6}$ He total energy versus angle spectrum places strict limits on the allowed excitation energy of the $^{210}$ Pb residual, so constraining distorted wave Born approximation calculations that the contribution of the 2n stripping process to the inclusive $^{6}$ He production can only be relatively small. It is therefore concluded that the dominant $^{6}$ He production mechanism must be 1n stripping followed by decay of the $^{7}$ He ejectile. Based on this result we present strong arguments in favor of direct, one step four-neutron (4n) stripping as the main mechanism for $^{4}$ He production.
Comments:
7 pages, 2 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2009.12801 [pdf]
PRC(2020)·5 citations
14
[Submitted on 28 Sept 2020] (cross-list from hep-lat)
Flavor decomposition for the proton helicity parton distribution functions
C. Alexandrou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · M. Constantinou (Temple Univ.)🇺🇸 · K. Hadjiyiannakou (Univ. of Cyprus)🇨🇾 · K. Jansen (DESY-Zeuthen)🇩🇪 · F. Manigrasso (Univ. of Cyprus, Humboldt Univ., Univ. of Rome Tor Vergata)🇨🇾
We present, for the first time, an \textit{ab initio} calculation of the individual up, down and strange quark helicity parton distribution functions for the proton. The calculation is performed within the twisted mass clover-improved fermion formulation of lattice QCD using one ensemble of dynamical up, down, strange and charm quarks with a pion mass of 260 MeV. The lattice matrix elements are non-perturbatively renormalized and the final results are presented in the $MS$ scheme at a scale of 2 GeV. We give results on the $Δ u^{+} (x)$ and $Δ d^{+} (x)$ , including disconnected quark loop contributions, as well as on the $Δ s^{+} (x)$ . For the latter we achieve unprecedented precision compared to the phenomenological estimates.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2009.13061 [pdf]
PRL(2021)·51 citations
15
[Submitted on 28 Sept 2020] (cross-list from hep-ph)
Chemical freeze-out systematics of thermal model analysis using hadron yield ratios
Sumana Bhattacharyya🇮🇳 · Amaresh Jaiswal🇮🇳 · Sutanu Roy🇮🇳
We provide a framework to estimate the systematic uncertainties in chemical freeze-out parameters extracted from $χ^{2}$ analysis of thermal model, using hadron multiplicity ratios in relativistic heavy-ion collision experiments. Using a well known technique of graph theory, we construct all possible sets of independent ratios from available hadron yields and perform $χ^{2}$ minimization on each set. We show that even for ten hadron yields, one obtains a large number ( $1 0^{8}$ ) of independent sets which results in a distribution of extracted freeze-out parameters. We analyze these distributions and compare our results for chemical freeze-out parameters and associated systematic uncertainties with previous results available in the literature.
Comments:
11 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2009.13399 [pdf]
PRC(2021)·6 citations
16
[Submitted on 28 Sept 2020] (cross-list from hep-ph)
Polarization as a signature of local parity violation in hot QCD matter
F. Becattini (Univeristy of Florence)🇮🇹 · M. Buzzegoli (Iowa State U.)🇮🇹 · A. Palermo (University of Florence)🇮🇹 · G. Prokhorov (JINR, Dubna)🇷🇺
We show that local parity violation due to chirality imbalance in relativistic nuclear collisions can be revealed by measuring the projection of the polarization vector onto the momentum, i.e. the helicity, of final state baryons. The proposed method does not require a coupling to the electromagnetic field, like in the Chiral Magnetic Effect. By using linear response theory, we show that, in the presence of a chiral imbalance, the spin 1/2 baryons and anti-baryons receive an additional contribution to the polarization along their momentum and proportional to the axial chemical potential. The additional, parity-breaking, contribution to helicity can be detected by studying helicity-helicity azimuthal angular correlation.
Comments:
13 pages, 3 figures; final version to appear in Physics Letters B
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2009.13449 [pdf]
PLB(2021)·22 citations
17
[Submitted on 28 Sept 2020] (cross-list from quant-ph)
Preparation of excited states for nuclear dynamics on a quantum computer
Alessandro Roggero · Chenyi Gu · Alessandro Baroni · Thomas Papenbrock
We study two different methods to prepare excited states on a quantum computer, a key initial step to study dynamics within linear response theory. The first method uses unitary evolution for a short time $T = O (1 - F)$ to approximate the action of an excitation operator $O^$ with fidelity $F$ and success probability $P \approx 1 - F$ . The second method probabilistically applies the excitation operator using the Linear Combination of Unitaries (LCU) algorithm. We benchmark these techniques on emulated and real quantum devices, using a toy model for thermal neutron-proton capture. Despite its larger memory footprint, the LCU-based method is efficient even on current generation noisy devices and can be implemented at a lower gate cost than a naive analysis would suggest. These findings show that quantum techniques designed to achieve good asymptotic scaling on fault tolerant quantum devices might also provide practical benefits on devices with limited connectivity and gate fidelity.
Comments:
25 pages, 19 figures (some circuits shown as figures); small modifications; title changed; version accepted for publication
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2009.13485 [pdf]
PRC(2020)·67 citations
18
[Submitted on 28 Sept 2020] (cross-list from hep-ph)
A Review on Partial-wave Dynamics with Chiral Effective Field Theory and Dispersion Relation
De-Liang Yao🇨🇳 · Ling-Yun Dai🇨🇳 · Han-Qing Zheng🇨🇳 · Zhi-Yong Zhou🇨🇳
The description of strong interaction physics of low-lying resonances is out of the valid range of perturbative QCD. Chiral effective field theories have been developed to tackle the issue. Partial wave dynamics is the systematic tool to decode the underlying physics and reveal the properties of those resonances. It is extremely powerful and helpful for our understanding of the non-perturbative regime, especially when dispersion techniques are utilized simultaneously. Recently, plenty of exotic/ordinary hadrons have been reported by experiment collaborations, e.g. LHCb, Belle, and BESIII, etc.. In this review, we summarize the recent progress on the applications of partial wave dynamics combined with chiral effective field theories and dispersion relations, on related topics, with emphasis on $π π$ , $π K$ , $π N$ and $K ˉ N$ scatterings.
Comments:
69 pages, 10 figures, 7 tables, to be the same as the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2009.13495 [pdf]
Rept.Prog.Phys.(2021)·91 citations

Affiliations

first authorsco-authorsvia INSPIRE