Nuclear Theory·nucl-th

Wednesday·September 1, 2021

14 papers—8 primary·6 cross-listed

01
BCS solutions and effective quarks energies of the QCD Hamiltonian in the Coulomb gauge
Tochtli Yepez-Martinez🇲🇽 · Peter O. Hess🇲🇽 · Osvaldo Civitarese🇦🇷
The exploration of the non-perturbative regime of QCD, that is the low-energy portion of the hadron spectrum, requires the adoption of theoretical methods more frequently applied to other, more conventional, quantum many body systems, like the atomic nucleus, solid state systems, etc. In this work we have adopted, as a first step, the well-known BCS method to describe correlations between pairs of quarks and the associated ground state. Going beyond the BCS method would imply the inclusion of correlations by means of the TDA or RPA approximations. Since, we are interested in analyzing the role of constituent quark-pair correlations in the structure of hadrons we are restricted to the use of BCS as said before. The starting Hamiltonian is the effective Coulomb plus linear potential which we have used in previous calculations and performed a two-step approach, firstly by pre-diagonalizing it to built a single particle spectrum, and then, secondly, by applying the BCS transformations to it. Then, we have explored the resulting structure of the low energy meson spectra in terms of quasiparticle degrees of freedom. The dependence of the results upon the parameters which enter in the calculations is explored in detail, at the level of the quasiparticle mean-field approximation.
nucl-thNPA(2023)·3 citations
02
Production of neutron-rich heavy nuclei around N = 162 in multinucleon transfer reactions
Cheng Peng · Zhao-Qing Feng
Within the framework of the dinuclear system model, the production mechanism of neutron-rich heavy nuclei around N = 162 has been investigated systematically. The isotopic yields in the multinucleon transfer reaction of $^{238}$ U + $^{248}$ Cm was analyzed and compared the available experimental data. Systematics on the production of superheavy nuclei via $^{238}$ U on $^{252, 254}$ Cf, $^{254}$ Es and $^{257}$ Fm is investigated. It is found that the shell effect is of importance in the formation of neutron-rich nuclei around N=162 owing to the enhancement of fission barrier. The fragments in the multinucleon transfer reactions manifest the broad isotopic distribution and are dependent on the beam energy. The polar angles of the fragments tend to the forward emission with increasing the beam energy. The production cross sections of new isotopes are estimated and heavier targets are available for the neutron-rich superheavy nucleus formation. The optimal system and beam energy are proposed for the future experimental measurements.
nucl-thEPJA(2022)·5 citations
03
Systematics on production of superheavy nuclei $Z = 119 - 122$ in fusion-evaporation reactions
Fei Niu · Peng-Hui Chen · Zhao-Qing Feng
The fusion dynamics on the formation of superheavy nuclei is investigated thoroughly within the dinuclear system model. The Monte Carlo approach is implemented into the nucleon transfer process for including all possible orientations, at which the dinuclear system is assumed to be formed at the touching configuration of dinuclear fragments. The production cross sections of superheavy nuclei Cn, Fl, Lv, Ts and Og are calculated and compared with the available data from Dubna. The evaporation residue excitation functions in the channels of pure neutrons and charged particles are analyzed systematically. The combinations with $^{44}$ Sc, $^{48, 50}$ Ti, $^{49, 51}$ V, $^{52, 54}$ Cr, $^{58, 62}$ Fe and $^{62, 64}$ Ni bombarding the actinide nuclides $^{238}$ U, $^{244}$ Pu, $^{248}$ Cm, $^{247, 249}$ Bk, $^{249, 251}$ Cf, $^{252}$ Es and $^{243}$ Am are calculated for producing the superheavy elements with Z=119-122. It is found that the production cross sections sensitively depend on the neutron richness of reaction system. The structure of evaporation residue excitation function is related to the neutron separation energy and fission barrier of compound nucleus.
nucl-thNucl.Sci.Tech.(2021)·25 citations
04
First-order Phase Transition and Resulted Expansion in Momentum Space
Feng Li🇨🇳
We point out, according to the principle of entropy growth, that the volume occupied by the system in the momentum space should expand during the first-order phase transition. Such an expansion is visualized by the simulation using the transport model based on a NJL-typed Lagrangian, and quantified by several observables, some of which, proposed for the first time in this article, could be the probes of the first-order phase transition either between the quark gluon plasma and the hadronic phase taking place in the heavy-ion collisions or of the other expanding systems.
nucl-thnucl-ex0 citations
05
Three-body optical potentials in $(d, p)$ reactions and their influence on indirect study of stellar nucleosynthesis
M. J. Dinmore · N.K. Timofeyuk · J.S. Al-Khalili
Model uncertainties, arising due to suppression of target excitations in the description of deuteron scattering and resulting in a modification of the two-body interactions in a three-body system, are investigated for several $(d, p)$ reactions serving as indirect tools for studying the astrophysical $(p, γ)$ reactions relevant to $r p$ -process. The three-body nature of deuteron-target potential is treated within adiabatic distorted wave approximation (ADWA) which relies on dominant contribution from the components of the three-body deuteron-target wave function with small $n$ - $p$ separations. This results in a simple prescription for treating the explicit energy-dependence of two-body optical potentials in a three-body system requiring nucleon optical potentials to be evaluated at a shifted energy with respect to the standard value of half the deuteron incident energy. In addition, the ADWA allows for leading-order multiple scattering effects to be estimated, which leads to a simple renormalization of the adiabatic potential's imaginary part by the factor of two. These effects are assessed using both nonlocal and local optical potential systematics for $^{26}$ Al, $^{30}$ P, $^{34}$ Cl and $^{56}$ Ni targets at deuteron incident energy of 12 MeV typical for experiments with radioactive beams in inverse kinematics. The model uncertainties induced by the three-body nature of deuteron-target scattering are found to be within 40 $%$ both in the main peak of angular distributions and in total $(d, p)$ cross sections. At higher deuteron energies, around 60 MeV, model uncertainties can reach 100\% in the total cross sections. A few examples of application to astrophysically interesting proton resonances in $^{27}$ Si and $^{57}$ Cu obtained using $(d, p)$ reactions and mirror symmetry are given.
nucl-thnucl-exPRC(2021)·2 citations
06
Structure of ultra-magnetised neutron stars
Debarati Chatterjee🇮🇳 · Jerome Novak🇫🇷 · Micaela Oertel🇫🇷
In this review we discuss self-consistent methods to calculate the global structure of strongly magnetised neutron stars within the general-relativistic framework. We outline why solutions in spherical symmetry cannot be applied to strongly magnetised compact stars, and elaborate on a consistent formalism to compute rotating magnetised neutron star models. We also discuss an application of the above full numerical solution for studying the influence of strong magnetic fields on the radius and crust thickness of magnetars. The above technique is also applied to construct a "universal" magnetic field profile inside the neutron star, that may be useful for studies in nuclear physics. The methodology developed here is particularly useful to interpret multi-messenger astrophysical data of strongly magnetised neutron stars.
nucl-thastro-ph.HEEPJA(2021)·22 citations
07
The BEST framework for the search for the QCD critical point and the chiral magnetic effect
Xin An🇺🇸 · Marcus Bluhm🇫🇷 · Lipei Du🇺🇸 · Gerald V. Dunne🇺🇸 · Hannah Elfner🇩🇪 · Charles Gale🇨🇦 · Joaquin Grefa🇺🇸 · Ulrich Heinz🇺🇸 · Anping Huang🇺🇸 · Jamie M. Karthein🇺🇸 · Dmitri E. Kharzeev🇺🇸 · Volker Koch🇺🇸 and 31 other authors
The Beam Energy Scan Theory (BEST) Collaboration was formed with the goal of providing a theoretical framework for analyzing data from the Beam Energy Scan (BES) program at the relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory. The physics goal of the BES program is the search for a conjectured QCD critical point as well as for manifestations of the chiral magnetic effect. We describe progress that has been made over the previous five years. This includes studies of the equation of state and equilibrium susceptibilities, the development of suitable initial state models, progress in constructing a hydrodynamic framework that includes fluctuations and anomalous transport effects, as well as the development of freezeout prescriptions and hadronic transport models. Finally, we address the challenge of integrating these components into a complete analysis framework. This document describes the collective effort of the BEST Collaboration and its collaborators around the world.
nucl-thhep-lathep-phnucl-exNPA(2022)·152 citations
08
Consequences of increased hypertriton binding for $s$ -shell $Λ$ -hypernuclear systems
M. Schäfer🇮🇱 · B. Bazak🇮🇱 · N. Barnea🇮🇱 · A. Gal🇮🇱 · J. Mareš🇨🇿
Consequences of increasing the binding energy of the hypertriton ground state $_{Λ}^{3} H (J^{P} = \frac{1}{2}^{+})$ from the emulsion value $B_{Λ}^{EMUL} (_{Λ}^{3} H_{g.s.})$ =0.13 $\pm$ 0.05 MeV to the STAR value $B_{Λ}^{STAR} (_{Λ}^{3} H) = (0.41 \pm 0.12 \pm 0.11)$ MeV are studied for $s$ -shell hypernuclei within a pionless EFT approach at leading order, constrained by the binding energies of the $0^{+}$ and $1^{+}$ $_{Λ}^{4} H$ states. The stochastic variational method is used in bound-state calculations, whereas the inverse analytic continuation in the coupling constant method is used to locate $S$ -matrix poles of continuum states. It is found that the $Λ nn (\frac{1}{2}^{+})$ resonance becomes broader and less likely to be observed experimentally, whereas the $_{Λ}^{3} H (\frac{3}{2}^{+})$ spin-flip virtual state moves closer to the $Λ d$ threshold to become a shallow bound state for specific $Λ N$ interaction strengths. The effect of such a near-threshold $_{Λ}^{3} H (\frac{3}{2}^{+})$ state on femtoscopic studies of $Λ$ -deuteron correlations, and its lifetime if bound, are discussed. Increasing $B_{Λ} (_{Λ}^{3} H_{g.s.})$ moderately, up to $\sim$ 0.5 MeV, hardly affects calculated values of $B_{Λ} (_{Λ}^{5} He)$ .
nucl-thPRC(2022)·10 citations
09
Lightweight self-conjugate nucleus $^{80}$ Zr
A. Hamaker (1,2,3)🇺🇸 · E. Leistenschneider (1,2,6)🇺🇸 · R. Jain (1,2,3)🇺🇸 · G. Bollen (1,2,3)🇺🇸 · S.A. Giuliani (1,4,5)🇺🇸 · K. Lund (1,2)🇺🇸 · W. Nazarewicz (1,3)🇺🇸 · L. Neufcourt (1)🇺🇸 · C. Nicoloff (1,2,3)🇺🇸 · D. Puentes (1,2,3)🇺🇸 · R. Ringle (1,2)🇺🇸 · C.S. Sumithrarachchi (1,2)🇺🇸 · I.T. Yandow (1,2,3) ((1) Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan, USA, (2) National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan, USA, (3) Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan, USA, (4) European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*-FBK), Trento, Italy, (5) Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey, United Kingdom, (6) CERN, Geneva, Switzerland)
Protons and neutrons in the atomic nucleus move in shells analogous to the electronic shell structures of atoms. Nuclear shell structure varies across the nuclear landscape due to changes of the nuclear mean field with the number of neutrons $N$ and protons $Z$ . These variations can be probed with mass differences. The $N = Z = 40$ self-conjugate nucleus $^{80}$ Zr is of particular interest as its proton and neutron shell structures are expected to be very similar, and its ground state is highly deformed. In this work, we provide evidence for the existence of a deformed double shell closure in $^{80}$ Zr through high precision Penning trap mass measurements of $^{80 - 83}$ Zr. Our new mass values show that $^{80}$ Zr is significantly lighter, and thus more bound than previously determined. This can be attributed to the deformed shell closure at $N = Z = 40$ and the large Wigner energy. Our statistical Bayesian model mixing analysis employing several global nuclear mass models demonstrates difficulties with reproducing the observed mass anomaly using current theory.
↳ nucl-exnucl-thNat.Phys.(2021)·38 citations
10
Ratios of jet and hadron spectra at LHC energies: measuring high- $p_{T}$ suppression without a $pp$ reference
Jasmine Brewer🇨🇭 · Alexander Huss🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Wilke van der Schee🇨🇭
We analyze the reliability of several techniques for computing jet and hadron spectra at different collision energies. This is relevant for discovering energy loss in the upcoming oxygen-oxygen (OO) run at the LHC, for which a reference pp run is currently not planned. For hadrons and jets we compute the ratio of spectra between different pp collision energies in perturbative QCD, which can be used to construct a reference spectrum. Alternatively, it can be interpolated from measured spectra at nearby energies. We estimate the precision of both strategies for the spectra ratio relevant to the oxygen run, and conclude that the central values agree to 4% accuracy for hadrons and 2% accuracy for jets. Finally we propose taking the ratio of OO and pp spectra at different collision energies, which cleanly separates the experimental measurement and theoretical computation.
↳ hep-phnucl-exnucl-thPRD(2022)·16 citations
11
Heavy-quark effects on cold quark matter and self-bound stars
José C. Jiménez🇧🇷 · Eduardo S. Fraga🇧🇷
Heavy-quark effects on the equation of state for cold and dense quark matter are obtained from perturbative QCD, yielding observables parametrized only by the renormalization scale. In particular, we investigate the thermodynamics of charm quark matter under the constraints of $β$ equilibrium and electric charge neutrality in a region of densities where perturbative QCD is, in principle, much more reliable. Finally, we analyze the stability of charm stars, a possible new branch of ultradense, self-bound compact stars, and find that they are unstable under radial oscillations.
↳ hep-phastro-ph.HEnucl-thEPJ Web Conf.(2022)·0 citations
12
Charm and beauty in the deconfined plasma from quenched lattice QCD
Heng-Tong Ding🇨🇳 · Olaf Kaczmarek🇨🇳 · Anna-Lena Lorenz🇩🇪 · Hiroshi Ohno🇯🇵 · Hauke Sandmeyer🇩🇪 · Hai-Tao Shu🇩🇪
We present continuum extrapolated results of charmonium and bottomonium correlators in the vector channel at several temperatures below and above $T_{c}$ . The continuum extrapolation jointly performed with the interpolations to have physical values of $J / ψ$ and $Υ$ masses in the confined phase is based on calculations on several large quenched isotropic lattices using clover-improved Wilson valence fermions carrying different quark masses. The extrapolated lattice correlators are confronted with perturbation theory results incorporating resummed thermal effects around the threshold from pNRQCD and vacuum asymptotics above the threshold. An additional transport peak is modelled below the threshold allowing for an estimate of the diffusion coefficients for charm and bottom quarks. We find that charmonium correlators in the vector channel can be well reproduced by perturbative spectral functions above $T_{c}$ where no resonance peaks for $J / ψ$ are needed at and above 1.1 $T_{c}$ , while for bottomonium correlators a resonance peak for $Υ$ is still needed up to 1.5 $T_{c}$ . By analyzing the transport contribution to the correlators we find that the drag coefficient of a charm quark is larger than that of a bottom quark.
↳ hep-lathep-phnucl-exnucl-thPRD(2021)·16 citations
13
Pionic depth of the hadron gas after a heavy-ion collision
Guillermo Gómez Fonfría🇪🇸 · Felipe J. Llanes-Estrada🇪🇸 · Javier Suárez Sucunza🇪🇸 · Juan M. Torres-Rincon🇩🇪
The final stage of a relativistic heavy-ion collision is a hadron gas. Final-state interactions therein distort the $p_{T}$ spectrum of particles coming from the phase transition upon cooling the quark-gluon plasma. Using recent state-of-the-art parametrizations of pion interactions we provide theoretical computations of the pionic depth of the gas: how likely is it that a given pion rescatters in it (we find a high probability around $p_{T} = 0.5$ GeV at midrapidity, corresponding to the formation of the $ρ$ resonance), a comparison of the collision and Bjorken expansion rates, and how many pions make it through without interacting as a function of $p_{T}$ . This is in the range 10-24 $%$ and shown in this plot, the main result of the contribution.
↳ hep-phnucl-thPoS(2022)·1 citation
14
Stellar Structure and Stability of Charged Interacting Quark Stars and Their Scaling Behaviour
Chen Zhang🇨🇦 · Michael Gammon🇨🇦 · Robert B. Mann🇨🇦
We explore the stellar structure and radial stability of charged quark stars composed of interacting quark matter (IQM) in three classes of commonly used charge models. We adopt a general parametrization of IQM equation of state that includes the corrections from perturbative QCD, color superconductivity, and the strange quark mass into one parameter $λ$ , or one dimensionless parameter $λ ˉ = λ^{2} / (4 B_{eff})$ after being rescaled with the effective bag constant $B_{eff}$ . We find that increasing charge tends to increase the mass and radius profiles, and enlarges the separation size in mass between the maximum mass point and the point where zero eigenfrequencies $ω_{0}^{2} = 0$ of the fundamental radial oscillation mode occur. The sign of the separation in central density depends on the charge model; this separation also has a dependence on $λ$ such that increasing $λ$ (which can occur for either large color superconductivity or small strange quark mass) tends to decrease this separation size for the first and third classes of charge models monotonically. Moreover, for the second and third classes of charge models, we manage to numerically and analytically identify a new kind of stellar structure with a zero central pressure but a finite radius and mass. All the calculations and analysis are performed in a general dimensionless rescaling approach so that the results are independent of explicit values of dimensional parameters.
↳ astro-ph.HEgr-qchep-phnucl-thPRD(2021)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE